Here’s another domestic CO Alarm, this one a cheaper build than the FireAngel ones usually use, these don’t have a display with the current CO PPM reading, just a couple of LEDs for status & Alarm.
Rear
This alarm also doesn’t have the 10-year lithium cell for power, taking AA cells instead. The alarm does have the usual low battery alert bleeps common with smoke alarms though, so you’ll get a fair reminder to replace them.
Internals
Not much at all on the inside. The CO sensor cell is the same one as used in the FireAngel alarms, I have never managed to find who manufactures these sensors, or a datasheet for them unfortunately.
PCB Top
The top of the single sided PCB has the transformer for driving the Piezo sounder, the LEDs & the test button.
PCB Bottom
All the magic happens on the bottom of the PCB. The controlling microcontroller is on the top right, with the sensor front end on the top left.
Circuitry Closeup
The microcontroller used here is a Microchip PIC16F677. I’ve not managed to find datasheets for the front end components, but these will just be a low-noise op-amp & it’s ancillaries. There will also be a reference voltage regulator. The terminals on these sensors are made of conductive plastic, probably loaded with carbon.
Sensor Cell & Piezo Disc
The expiry date is handily on a label on the back of the sensor, the Piezo sounder is just underneath in it’s sound chamber.
I thought it was time to add a bit of security to the gear I take camping, so this GPS tracker unit was sourced from eBay. This is a Rewire Security 103RS, a slightly customised version of the common Chinese TK103 GPS tracker.
Input Connections
The small module has all it’s power connections on one end of the unit, on a Molex multi-way block. The white connector is for a piezo-shock sensor – this interfaces with the alarm functionality of the unit. There’s an indicator LED for both the GPS & GSM status, and a switch for the backup battery.
Antenna Connections
The other end has the antenna connections, microphone connection for the monitor function, along with the SIM & SD card slots.
PCB Top
Once the end panel is removed, the PCB just slides out of the aluminium extruded casing. It’s pretty heavily packed with components in here. A switching regulator deals with the 12v input from the vehicle battery, and is protected by a polyfuse on the right. The GSM module is hiding under the Li-Po backup cell, unfortunately the sticky pad used to secure this wouldn’t come off without damaging something. The pigtails for both the GPS & GSM antennas are permanently soldered to the board here.
PCB Bottom
The bottom of the PCB has the GPS module, and mainly input protection & bypassing components. There is a FNK4421 Dual P-Channel MOSFET here as well, probably used for switching the external relay or alarm siren. The SIM socket for the GSM modem is located here in the corner.
Here’s the solar charge controller to go with the MT50 from the last post. This is the 40A version of the EpEver Tracer A series, the 4210A. This unit is large, and very heavy. Most of this weight comes from the enormous heatsink which doubles as the mounting plate for all the other components, and the large inductors that are going to be required for the DC-DC conversion that MPPT requires.
Front Panel
The front panel has a basic LCD, which shows various stats, such as PV Volts & Amps, and battery bank Volts & Amps. The pair of buttons are used to navigate the basic menu to configure some options, along with switching the load terminals ON/OFF.
Specifications
There’s a specs label on the top, with a slight difference here vs the manual, which states the max. PV volts as 92v.
Main PCB Overview
Removing 4 machine screws from the bottom of the unit allows the top to come off. Like the MT50 remote panel, this unit also has moulded-in brass thread inserts in the plastic parts. The PCB in here is heavily comformal coated, which stops me from reading the laser-etched numbers on the semiconductor devices, so there will be few details there.
Main PCB Lower
Here’s the bottom section of the main PCB, with the enormous screw terminals, which will easily take cables up to about 16mm². The RJ-45 jack which hosts the unit’s RS-485 bus is to the right, and a smaller 2-pin connector on the left sorts out the battery temperature sensor.
The DC output MOSFET switches are hiding just behind the right-hand terminals, there’s a pair of them in this unit to handle the output current. Some beefy diodes polarity-protect both the battery & PV inputs.
Board Centre
Moving up the board shows two 35A automotive blade fuses soldered into the board – these would be a real pain to replace if they ever blew, however with the electronic load current protection built into this unit, it’s an unlikely situation, unless something went hideously wrong. The main switching devices for the DC-DC converter are hidden – they’re clamped to the heatsink with the bars at right angles in the photo, I’m not going to dig any deeper into this just for those though – they’re just TO220 devices.
Under a load of thermal gunk on the right are 4 current shunt resistors, and the amplifiers for reading their values. These 1206-size SMD resistors looked a bit small for the power rating to me, but they’re heatsinked in operation to a small heatsink mounted in the top cover.
Board Upper
The upper section of the PCB hosts the main microcontroller, and the connections over to the front panel LCD & buttons. Couldn’t really get much info from these chips, due to the conformal coating.
Toroidal Inductors
Right at the top of the unit are these toroidal inductors, potted into aluminium housings. The copper windings of these is very heavy – at least 2.5mm². They’re electrically in parallel, the 20A version would only have a single inductor.
Current Shunt Heatsink
This small heatsink sits inside the top cover, and provides some cooling to the current shunts.
Display Board
Not much to say for the display board, there’s going to be nothing here apart from an I²C LCD driver & the pair of front panel buttons, so I won’t bother removing this from the case.
This is a chip aimed at the automotive market – this is a low power voltage regulator for supplying power to microcontrollers, for instance in a CD player.
TDA3606 Die
The TDA3606 is a voltage regulator intended to supply a microprocessor (e.g. in car radio applications). Because of low voltage operation of the application, a low-voltage drop regulator is used in the TDA3606. This regulator will switch on when the supply voltage exceeds 7.5 V for the first time and will switch off again when the output voltage of the regulator drops below 2.4 V. When the regulator is switched on, the RES1 and RES2 outputs (RES2 can only be HIGH when RES1 is HIGH) will go HIGH after a fixed delay time (fixed by an external delay capacitor) to generate a reset to the microprocessor. RES1 will go HIGH by an internal pull-up resistor of 4.7 kΩ, and is used to initialize the microprocessor. RES2 is used to indicate that the regulator output voltage is within its voltage range. This start-up feature is built-in to secure a smooth start-up of the microprocessor at first connection, without uncontrolled switching of the regulator during the start-up sequence. All output pins are fully protected. The regulator is protected against load dump and short-circuit (foldback
current protection). Interfacing with the microprocessor can be accomplished by means of a battery Schmitt-trigger and output buffer (simple full/semi on/off logic applications). The battery output will go HIGH when the battery input voltage exceeds the HIGH threshold level.
Here’s an eBay oddity – it’s got the same light & lens mechanism as the cheap “disco light” style bulbs on eBay, but this one is battery powered & has a built in MP3 player.
MP3 Disco Light
This device simply oozes cheapness. The large 4″ plastic dome lens sits on the top above the cheap plastic moulding as a base, which also contains the MP3 player speaker.
Controls
There are few controls on this player, the volume buttons are combined with the skip track buttons, a long press operates the volume control, while a short press skips the tracks. Several options for getting this thing to play music are provided:
Bluetooth – Allows connection from any device for bluetooth audio
USB – Plugging in a USB flash drive with MP3 files
SD Card – Very similar to the USB flash drive option, just a FAT32 formatted card with MP3 files
Aux – There’s no 3.5mm jack on this unit for an audio input, instead a “special” USB cable is supplied that is both used to charge the built in battery & feed an audio signal. This is possible since the data lines on the port aren’t used. But it’s certainly out of the ordinary.
Top Removed
The top comes off with the removal of a single screw in the centre of the lens. The shaft in the centre that holds the lens is attached to a small gear motor under the LED PCB. There’s 6 LEDs on the board, to form an RGB array. Surprisingly for a very small battery powered unit these are bright to the point of being utterly offensive.
Mainboard
Here’s the mainboard removed from the plastic base. There’s not much to this device, even with all the options it has. The power switch is on the left, followed by the Mini-B USB charging port & aux audio input. The USB A port for a flash drive is next, finishing with the µSD slot. I’m not sure what the red wire is for on the left, it connects to one of the pins on the USB port & then goes nowhere.
Audio Amplifier
The audio amplifier is a YX8002D, I couldn’t find a datasheet for this, but it’s probably Class D.
Main Chipset
Finally there’s the main IC, which is an AC1542D88038. I’ve not been able to find any data on this part either, it’s either a dedicated MP3 player with Bluetooth radio built in, or an MCU of some kind.The RF antenna for the Bluetooth mode is at the top of the board.
Just behind the power switch is a SOT23-6 component, which should be the charger for the built in Lithium Ion cell.
Lithium Ion Cell
The cell itself is a prismatic type rated in the instructions at 600mAh, however my 1C discharge test gave a reading of 820mAh, which is unusual for anything Li-Ion based that comes from eBay 😉
There is cell protection provided, it’s under the black tape on the end, nothing special here.
The main issue so far with this little player is the utterly abysmal battery life – at full volume playing MP3s from a SD card, the unit’s current draw is 600mA, with the seizure & blindness-inducing LEDs added on top, the draw goes up to about 1200mA. The built in charger is also not able to keep up with running the player while charging. This in all only gives a battery life of about 20 minutes, which really limits the usability of the player.
Here’s the other TV that was picked up from the local water point having been put of to be recycled. This one is much newer than the Thorn TV, a 10″ colour version from Ferguson.
RCA 27GDC85X CRT
The colour CRT used is an RCA branded one, 27GDC85X.
Power Inputs
Like the other TV, this one is dual voltage input, mains 240v & 12v battery. This TV is a factory conversion of a standard 240v AC chassis though.
HV PSU
The 12v power first goes into this board, which looked suspiciously like an inverter. Measuring on the output pins confirmed I was right, this addon board generates a 330v DC supply under a load, but it’s not regulated at all, under no load the output voltage shoots up to nearly 600v!
Live Chassis
I’ve not seen one of these labels on a TV for many years, when back in the very old TV sets the steel chassis would be used to supply power to parts of the circuitry, to save on copper. Although it doesn’t have a metal chassis to actually become live, so I’m not sure why it’s here.
Main PCB
The main PCB is much more integrated in this newer TV, from the mid 90’s, everything is pretty much taken care of by silicon by this point.
Main Microcontroller
This Toshiba µC takes care of channel switching & displaying information on the CRT. The tuner in this TV is electronically controlled.
PAL Signal Processor
The video signal is handled by this Mitsubishi IC, which is a PAL Signal Processor, this does Video IF, Audio IF, Chroma, & generates the deflection oscillators & waveforms to drive the yoke.
CRT Adjustments
There are some adjustments on the CRT neck board for RGB drive levels & cutoff levels. This board also had the final video amplifiers onboard, which drive the CRT cathodes.
The other day at the local canal-side waterpoint, this TV was dumped for recycling, along with another later model Colour TV. This is a 1970’s Black & White mains/battery portable made by Thorn. It’s based on a common British Radio Corporation 1590 chassis. Having received a soaking from rain, I didn’t expect this one to work very well.
Tuner
Being so old, there is no electronic control of the tuner in this TV, and only has the capability to mechanically store 4 different channels. The tuner itself is a cast box with a plastic cover.
Tuning Lever
The mechanical buttons on the front of the TV push on this steel bar, by different amounts depending on the channel setting. This bar is connected to the tuning capacitor inside the tuner.
Tuner Compartments
Unclipping the plastic cover, with it’s lining of aluminium foil for shielding reveals the innards of the tuner module.
Tuner Input Stage
Here’s the tuner front end RF transistor, which has it’s can soldered into the frame, this is an AF239 germanium UHF transistor, rated at up to 900MHz.
Tuner IF Mixer Stage
As the signal propagates through the compartments of the tuner, another transistor does the oscillator / IF mixing, an AF139 germanium, rated to 860MHz.
Tuning Capacitor
As the buttons on the front of the set are pushed, moving the lever on the outside, the tuning capacitor plates intermesh, changing the frequency that is filtered through the tuner. The outer blades of the moving plates are slotted to allow for fine tuning of the capacitance, and therefore transmitted frequency by bending them slightly.
Mains Transformer
Being a dual supply TV that can operate on either 12v battery power or mains, this one has a large centre tapped mains transformer that generates the low voltage when on AC power. Full wave rectification is on the main PCB. The fuse of this transformer has clearly been blown in the past, as it’s been wound with a fine fuse wire around the outside to repair, instead of just replacing the fuse itself.
Chassis Rear
The back of the set has all the picture controls on the bottom edge, with the power input & antenna connections on the left just out of shot. The CRT in this model is an A31-120W 12″ tube, with a really wide deflection angle of 110°, which allows the TV to be smaller.
Main PCB
The bottom of the mainboard has all the silkscreen markings for the components above which certainly makes servicing easier 😉 This board’s copper tracks would have been laid out with tape, obviously before the era of PCB design software.
Components
The components on this board are laid out everywhere, not just in square grids. The resistors used are the carbon composition type, and at ~46 years old, they’re starting to drift a bit. After measuring a 10K resistor at 10.7K, all of these would need replacing I have no doubt. Incedentally, this TV could be converted to take a video input without the tuner, by lifting the ferrite beaded end of L9 & injecting a signal there.
Flyback Primary Windings
The flyback (Line Output Transformer) is of the old AC type, with the rectifier stack on top in the blue tube, as opposed to more modern versions that have everything potted into the same casing. The primary windings are on the other leg of the ferrite core, making these transformers much more easily repairable. This transformer generates the 12kV required for the CRT final anode, along with a few other voltages used in the TV, for focussing, etc.
Rectifier Stack
The main EHT rectifier stack looks like a huge fuse, inside the ceramic tube will be a stack of silicon diodes in series, to withstand the high voltage present.
Horizontal Output Transistor
This is the main switching transistor that drives the flyback, the HOT. This is an AU113, another germanium type, rated at 250v 4A. The large diode next to the transistor is the damper.
I’ve managed to find all the service information for this set online, link below!
[download id=”5616″]
More to come if I manage to get this TV working!
Here’s a useful tool for testing both power supplies & batteries, a dummy load. This unit is rated up to 60W, at voltages from 1v to 25v, current from 200mA to 9.99A.
This device requires a 12v DC power source separate from the load itself, to power the logic circuitry.
Microcontroller Section
Like many of these modules, the brains of the operation is an STM8 microcontroller. There’s a header to the left with some communication pins, the T pin transmits the voltage when the unit is operating, along with the status via RS232 115200 8N1. This serial signal is only present in DC load mode, the pin is pulled low in battery test mode. The 4 pins underneath the clock crystal are the programming pins for the STM8.
Serial CommsCooling Fan
The main heatsink is fan cooled, the speed is PWM controlled via the microcontroller depending on the temperature.
Main MOSFET
The main load MOSFET is an IRFP150N from Infineon. This device is rated at 100v 42A, with a max power dissipation of 160W. On the right is a dual diode for reverse polarity protection, this is in series with the MOSFET. On the left is the thermistor for controlling fan speed.
Load Terminals
The load is usually connected via a rising clamp terminal block. I’ve replaced it with a XT60 connector in this case as all my battery holders are fitted with these. This also removes the contact resistance of more connections for an adaptor cable. The small JST XH2 connector on the left is for remote voltage sensing. This is used for 4-wire measurements.
Function 1 – DC Load
Powering the device up while holding the RUN button gets you into the menu to select the operating modes. Function 1 is simple DC load.
Function 2 – Battery Capacity Mode
The rotary encoder is used to select the option. Function 2 is battery capacity test mode.
Beeper Mode
After the mode is selected, an option appears to either turn the beeper on or off.
Amps Set
When in standby mode, the threshold voltage & the load current can be set. Here the Amps LED is lit, so the load current can be set. The pair of LEDs between the displays shows which digit will be changed. Pressing the encoder button cycles through the options.
Volts Set
With the Volts LED lit, the threshold voltage can be changed.
When in DC load mode (Fun1), the device will place a fixed load onto the power source until it’s manually stopped. The voltage setting in this mode is a low-voltage alarm. The current can be changed while the load is running.
When in battery discharge test mode (Fun2), the voltage set is the cutoff voltage – discharge will stop when this is reached. Like the DC load mode, the current can be changed when the load is running. After the battery has completed discharging, the capacity in Ah & Wh will be displayed on the top 7-segment. These results can be selected between with the encoder.
Below are tables with all the options for the unit, along with the error codes I’ve been able to decipher from the Chinese info available in various places online. (If anyone knows better, do let me know!).
Option
Function
Fun1
Basic DC Load
Fun 2
Battery Capacity Test
BeOn
Beeper On
BeOf
Beeper Off
Error Code
Meaning
Err1
Input Overvoltage
Err2
Low Battery Voltage / No Battery Present / Reverse Polarity
Err3
Battery ESR Too High / Cannot sustain selected discharge current
Err4
General Failure
Err6
Power Supply Voltage Too Low / Too High. Minimum 12v 0.5A.
Here’s another battery charger designed for lithium chemistry cells, the BLU4. This charger doesn’t display much on it’s built in LCD, apart from basic cell voltage & charging current limits, as it has a built in Bluetooth module that will link into an Android or iOS app.
Above the charger is operating with 4 brand new cells, at a current of 500mA per cell. If only a pair of cells is being charged, the current can be increased to 1A per cell.
LCD
Not much in the way of user interface on the charger, a tiny LCD & single button for cycling through the display options.
Dataplate
The usual stuff on the data plate, the charger accepts an input of 12v DC at 1A.
Bottom Cover Removed
Removing the 6 screws on the bottom of the casing allows the board to be seen. Not much on the bottom, the 4 cell negative connections can be seen, with their springs for adjusting for cell length.
MOSFETs
There’s a couple of P-Channel FETs on the bottom side for the charging circuits, along with some diodes.
Main PCB
The main PCB is easily removed after the springs are unhooked from the terminals. Most of the power circuitry is located on the top side near the power input. There are 4 DC-DC converters on board for stepping the input 12v down to the 4.2v required to charge a lithium cell.
Second Controller
Not entirely sure what this IC is in the bottom corner, as it’s completely unmarked. I’m guessing it’s a microcontroller though.
DC Input Side
The top left of the board is crammed with the DC-DC converters, all the FETs are in SO8 packages.
DC-DC Converters
One pair of DC-DC inductors is larger than the other pair, for reasons I’m unsure of.
Bluetooth Module
Bluetooth connectivity is provided by this module, which is based around a TTC2541 BLE IC.
Microcontroller
Below the Bluetooth module is yet another completely unmarked IC, the direct link to the BLE interface probably means it’s another microcontroller. The Socket to the left of the IC is the connector for the front panel LCD & button.
LCD PCB
There’s not much to the LCD itself, so I won’t remove this board. The LCD controller is a COB type device, from the number of connections it most likely communicates with the micro via serial.
I recently decided to restock my toolkit, as there are plenty of jobs I need to sort that require the use of crimp terminals, so eBay again came to the rescue.
In my experience, cheap tools of any flavour are usually universally shite – I’ve had drill bits made out of a metal softer than aluminium, that unwind back into a straight flute bits as soon as they’re presented with anything harder to drill through than Cheese. Ditto for screwdrivers. But for once the far eastern factories seem to have done a reasonable job on this crimp tool set.
eBay Crimping Tools
These are ratchet type crimping pliers, with interchangable heads so many different types of terminals can be used. A handy Philips screwdriver is included in the kit for changing the dies.
Large Dies
The largest dies in the set can handle cable up to 25mm² – just about the bottom end of main battery cables, which is very handy.
Medium Dies
Smaller sets of dies are provided for other types of terminals.
Small Dies
I’m not precisely sure which type of terminals these dies fit – the profile is a bit unusual.
Tiny Dies
The smallest dies in the set are good for extremely small wires – down to 0.5mm
Automotive Dies
The pliers are supplied with the standard colour-coded automotive dies installed. Sometimes these terminals never crimp properly, as the dies just effectively crush the copper tube of the terminal, so more often than not the wire strands are just forced out of the terminal as the crimp is made, leaving a bad connection.
These are even better than the ratchet-type crimp tools at the local Maplin Electronics – the set of those I have just distorts when a large crimp is made, so the terminal never gets a full crimp. The steel is not stiff enough to handle the forces required.
Example Crimp
Here’s a couple of large crimps on 6mm² cable attached to an ammeter. The crimps are nice & tight & hold onto the cable securely. The insulating sleeve on the terminals also hasn’t been cut through by the dies, which is often a problem on cheap crimp tools.
Recently my phone decided it was going to die a battery-related death, and having not found much useful information on the Great Google, (all the information I could find, was hinting at many issues from firmware to a faulty motherboard, nobody seems to have actually done any investigation into similar issues), I decided to dig into the phone to try & repair the problem.
Broken Flex
The phone would work correctly for a while, then with the slightest movement or knock, would spontaneously switch off, and not turn back on without being whacked on a hard surface.
This symptom pointed me at a power connection problem. After removing the back of the phone (glass & heavily glued in place, so an awkward process), This was what I was presented with on the cell flex PCB.
In the above photo, the positive connection to the flex is fractured just after the solder joint with the BMS board.
Flex Repair
I managed to scrape some of the insulation off the flex PCB & solder a jumper on to restore power. Unfortunately, this repair generated another fault, where the battery level was always shown at 50%, and plugging into a USB supply wouldn’t charge the phone. The other two pins on the cell are for communication & temperature sensing, clearly one of these traces was also broken in the flex.
The above photo has a pair of very small wire tails as well, for connecting an external charger.
50% Battery
Here’s a screenshot of the phone with the original cell, even though it’s at about 4.15v (virtually fully charged). The battery management is having trouble talking to the phone, so for safety reasons, the charging logic refuses point-blank to charge the thing up.
Flex Cable
The connector on the cell & phone motherboard is absolutely tiny, so I didn’t fancy attempting to solder on any bridge wires to try & bypass the broken flex.
Battery BMS
The cell BMS has some intelligence on board, besides the usual over-current, over-charge & under-charge protection. The very small IC on the right has a Microchip logo, and the marking FT442, but I was unable to dig up any datasheets. The current sense resistor is directly connected to this IC, along with the main power FET to the left.
BMS Reverse
On the other side of the BMS board is another IC, again unidentifiable, and what looks like a bare-die, or CSP IC.
At this stage I figured the only way forward was to buy a new battery, eBay turned one up for less than £5. Above is the new battery fitted to the phone, datestamped 2014, so definitely old stock.
100% Battery
Booting the phone with the new battery quickly lets me know the fix worked, with a 100% reading & the ability to again charge properly!
I recently came across these on eBay, so I thought I’d grab one to see how they function, with all the metrics they display, there’s potential here for them to be very useful indeed.
One of the best parts is that no wiring is required between the sensor board & the LCD head unit – everything is transmitted over a 2.4GHz data link using NRF24L01 modules.
Above is the display unit, with it’s colour LCD display. Many features are available on this, & they appear to be designed for battery powered systems.
Monitor PCB
Another PCB handles the current & voltage sensing, so this one can be mounted as close to the high current wiring as possible.
Monitor PCB Microcontroller
The transmitter PCB is controlled with an STM8S003F3 microcontroller from ST Microelectronics. This is a Flash based STM with 8KB of ROM, 1KB of RAM & 10-bit ADC. The NRF24L01 transceiver module is just to the left.
There’s only a single button on this board, for pairing both ends of the link.
Output MOSFET
The high current end of the board has the 0.0025Ω current shunt & the output switch MOSFET, a STP75NF75 75v 75A FET, also from ST Microelectronics. A separate power source can be provided for the logic via the blue terminal block instead of powering from the source being measured.
LCD Unit Rear
Here’s the display unit, only a pair of power terminals are provided, 5-24v wide-range input is catered for.
LCD Unit PCB
Unclipping the back of the board reveals the PCB, with another 2.4GHz NRF24L01 module, and a STM8S005K6 microcontroller in this case. The switching power supply that handles the wide input voltage is along the top edge of the board.
Unfortunately I didn’t get any instruction manual with this, so some guesswork & translation of the finest Chinglish was required to get my head round the way everything works. To make life a little easier for others that might have this issue, here’s a list of functions & how to make them work.
LCD Closeup
On the right edge of the board is the function list, a quick press of the OK button turns a function ON/OFF, while holding it allows the threshold to be set.
When the output is disabled by one of the protection functions, turning that function OFF will immediately enable the output again.
The UP/DOWN buttons obviously function to select the desired function with the cursor just to the left of the labels. Less obviously though, pressing the UP button while the very top function is selected will change the Amp-Hours display to a battery capacity icon, while pressing DOWN while the very bottom function is selected will change the Watts display to Hours.
The round circle to the right displays the status of a function. Green for OK/ON Grey for FAULT/OFF.
OVP: Over voltage protection. This will turn off the load when the measured voltage exceeds the set threshold.
OPP: Over power protection. This function prevents a load from pulling more than a specified number of watts from the supply.
OCP: Over current protection. This one’s a little more obvious, it’ll disable the output when the current measured exceeds the specified limit.
OUT: This one is the status of the output MOSFET. Can also be used to manually enable/disable the output.
OFT: Over time protection. This one could be useful when charging batteries, if the output is enabled for longer than the specified time, the output will toggle off.
OAH: Over Amp-Hours protection. If the counted Amp-Hours exceeds the set limit, the output will be disabled.
Nom: This one indicates the status of the RF data link between the modules, and can be used to set the channel they operate on.
Pairing is achieved by holding the OK button, selecting the channel on the LCD unit, and then pressing the button on the transmitter board. After a few seconds, (it appears to scan through all addresses until it gets a response) the display will resume updating.
This function would be required if there are more than a single meter within RF range of each other.
I’ve not yet had a proper play with all the protection functions, but a quick mess with the OVP setting proved it was very over-sensitive. Setting the protection voltage to 15v triggered the protection with the measured voltage between 12.5v-13.8v. More experimentation is required here I think, but as I plan to just use these for power monitoring, I’ll most likely leave all the advanced functions disabled.
This camera has now been retired after many years of heavy use. Exposure to a 3-year old has caused severe damage to the lens mechanism, which no longer functions correctly.
Rear Panel
Pretty much standard interface for a digital camera, with a nice large LCD for it’s time.
Front Cover Removed
With the front cover removed, the lens assembly & battery compartment is exposed.
Rear Cover Removed
Removing the rear cover exposes the LCD module & the main PCB, the interface tactile switches are on the right under a protective layer of Kapton tape.
Main Chipset
Flipping the LCD out of it’s mounting bracket reveals the main camera chipset. The CPU is a NovaTek NT96432BG, no doubt a SoC of some kind, but I couldn’t find any information. Firmware & inbuilt storage is on a Hynix HY27US08561A 256MBit NAND Flash, with a Hynix HY5DU561622FTP-D43 256Mbit DRAM for system memory.
I couldn’t find any info on the other two chips on this side of the board, but one is probably a motor driver for the lens, while the other must be the front end for the CCD sensor input to the SoC.
Main PCB Reverse
The other side of the PCB handles the SD card slot & power management. All the required DC rails are provided for by a RT9917 7-Channel DC-DC converter from RichTek, an IC designed specifically for digital camera applications.
Top left above the SD card slot is the trigger circuitry for the Xenon flash tube & the RTC backup battery.
Main PCB Removed
Once the main PCB is out of the frame, the back of the lens module with the CCD is accessible. Just to the left is the high-voltage photoflash capacitor, 110µF 330v. These can give quite the kick when charged! Luckily this camera has been off long enough for the charge to bleed off.
Sensor
Finally, here’s the 7-Megapixel CCD sensor removed from the lens assembly, with it’s built in IR cut filter over the top. I couldn’t find any make or model numbers on this part, as the Aluminium mounting bracket behind is bonded to the back of the sensor with epoxy, blocking access to any part information.
Die images of the chipset to come once I get round to decapping them!
I’m no fan of power inverters. In my experience they’re horrifically inefficient, have power appetites that make engine starter motors look like electric toothbrushes & reduce the life expectancy of lead-acid batteries to no more than a few days.
However I have decided to do a little analysis on a cheapo “600W” model that Maplin Electronics sells.
Cover Removed
After a serious amount of metallic abuse, the bottom cover eventually came off. The sheet of steel used to close the bottom of the aluminium extrusion was wedged into place with what was probably a 10 ton hydraulic press.
As can be seen from the PCB, there’s no massive 50Hz power transformer, but a pair of high frequency switching transformers. Obviously this is to lighten the weight & the cost of the magnetics, but it does nothing for the quality of the AC output waveform.
DC Input End
The 12v DC from the battery comes in on very heavy 8-gauge cables, this device is fused at 75A!
DC Fuses
Here’s the fusing arrangement on the DC input stage, just 3 standard blade-type automotive fuses. Interestingly, these are very difficult to get at without a large hammer & some swearing, so I imagine if the user manages to blow these Maplin just expect the device to be thrown out.
Input DC-DC Switching MOSFETs
On the input side, the DC is switched into the pair of transformers to create a bipolar high voltage DC supply.
High Voltage Rectifiers
The large rectifier diodes on the outputs of the transformers feed into the 400v 100µF smoothing capacitors.
As mains AC is obviously a bipolar waveform, I’m guessing this is generating a ±150v DC supply.
Output MOSFETs
After the high voltage is rectified & smoothed, it’s switched through 4 more MOSFETs on the other side of the PCB to create the main AC output.
The label states this is a modified-sine output, so I’d expect something on the scope that looks like this:
Inverter Waveforms
Modified-sine doesn’t look as bad as just a pure square output, but I suspect it’s a little hard on inductive loads & rectifiers.
However, after connecting the scope, here’s the actual waveform:
Actual Waveform
It’s horrific. It’s not even symmetrical. There isn’t even a true “neutral” either. The same waveform (in antiphase) is on the other mains socket terminal. This gives an RMS output voltage of 284v. Needless to say I didn’t try it under load, as I don’t possess anything I don’t mind destroying. (This is when incandescent lamps are *really* useful. Bloody EU ;)).
About the only thing that it’s accurate at reproducing is the 50Hz output, which it does pretty damn well.
System Microcontroller
As is usual these days, the whole system is controlled via a microcontroller.
I’ve been a vaper now for many years, after giving up the evil weed that is tobacco. Here’s my latest acquisition in the vaping world, the JoyeTech eVIC 60W. This one is branded by Totally Wicked as the Forza VT60.
18650 Cell
Powered by a single 18650 Li-Ion cell, this one is a Sony VTC4 series, 2100mAh.
Under the battery a pair of screws hold the electronics in the main cast alloy casing.
OLED Display
After removing the screws, the entire internal assembly comes out of the case, here’s the top of the PCB with the large OLED display in the centre.
USB Jack
On the right side of the board is the USB jack for charging & firmware updates. The adjustment buttons are also at this end.
Output
On the left side of the board is the main output connector & the fire button. Unlike many eCigs I’ve torn down before, the wiring in this one is very beefy – it has to be to handle the high currents used with some atomizers – up to 10A.
PCB Reverse
Removing the board from the battery holder shows the main power circuitry & MCU. The aluminium heatsink is thermally bonded to the switching MOSFETs, a pair under each end. The switching inductor is under the gap in the centre of the heatsink.
DC-DC Converter
A close up of the heatsink shows the very slim inductor under the heatsink.
Microcontroller
The main MCU in this unit has a very strange part number, which I’ve been unable to find information on, but it’s probably 8081 based.
With a recent order from a Chinese seller on eBay, this little gadget was included in the package as a freebie:
Electronic Lighter
I’ve not smoked for a long time, so I’m not too sure what use I’m going to find for this device, but it’s an electronic lighter!
Pyromaniac Mode
Pushing the slider forward reveals a red-hot heater, mounted in the plastic (!) frame.
Charging Mode
Pushing the other way reveals a USB port to charge the internal battery.
Core Removed
A couple of screws releases the end cap from the cover & the entire core unit slides out. Like all Chinese toys it’s made of the cheapest plastic imaginable, not such a good thing when heat is involved.
Heating Element
The element itself is a simple coil of Nichrome wire, crimped to a pair of brass terminals. The base the heater & it’s terminals are mounted to is actually ceramic – the surround though that this ceramic pill clips into is just the same cheap plastic. Luckily, the element only remains on for a few seconds on each button push, there’s no way to keep it on & start an in-pocket fire, as far as I can see.
Main PCB
The main PCB clips out of the back of the core frame, the large pair of tinned pads on the left connect to the heater, the control IC has no numbering of any kind, but considering the behaviour of the device it’s most likely a standard eCig control IC.
LiPo Cell
The other side of the board has the USB port on the right, the Lithium Polymer cell in the centre, and the power button on the left. The cell itself also has no marking, but I’m guessing a couple hundred mAh from the physical size.
This detector has now been retired from service since it’s a fair bit out of date. So here’s the teardown!
Information
Unlike older detectors, this unit has a built in battery that never needs replacing during the life of the sensor, so once the unit reaches it’s expiry date it’s just trashed as a whole.
Cover Removed
4 screws hold the cover on, here’s the internals of the detector. There’s a 3v CR123A LiMnO² cell at the right for power, rated at 1500mAh. A 7 year life is quite remarkable on a single cell!
The sensor is just to the left of the lithium cell, and is of quite unusual construction. Previous CO sensor cells I’ve seen have been small cylinders with a pair of brass pins. This one appears to use a conductive plastic as the connections. These sensors contain H²SO⁴ so they’re a bit hazardous to open.
There are no manufacturer markings on the sensor & I’ve not been able to find any similarly shaped devices, so I’m unsure of it’s specifications.
The alarm sounder is on the left, the usual Piezo disc with a resonator to increase the loudness.
Microcontroller
The brains of the device are provided by a Microchip PIC16F914 microcontroller. This is a fairly advanced device, with many onboard features, and NanoWatt™ technology, standby power consumption is <100nA according to Microchip’s Datasheet. This would explain the incredible battery life.
The choke just at the right edge of the photo is actually a transformer to drive the Piezo sounder at high voltage.
PCB Reverse
Here’s the PCB with the LCD frame removed. Not much to see on the this side, the silence/test button top right & the front end for the sensor.
Sensor Front End Amplifier
Here’s a closer look at the front end for the CO sensor cell itself. I haven’t been able to decode the SMT markings on the SOT packages, but I’m guessing that there’s a pair of OpAmps & a voltage reference.
The multimode dimming/flashing modes on Chinese torches have irritated me for a while. If I buy a torch, it’s to illuminate something I’m doing, not to test if people around me have photosensitive epilepsy.
Looking at the PCB in the LED module of the torch, a couple of components are evident:
LED Driver PCB
There’s not much to this driver, it’s simply resistive for LED protection (the 4 resistors in a row at the bottom of the board).
The components at the top are the multimode circuitry. The SOT-23 IC on the left is a CX2809 LED Driver, with several modes. The SOT-23 on the right is a MOSFET, for switching the actual LED itself. I couldn’t find a datasheet for the IC itself, but I did find a schematic that seems to match up with what’s on the board.
Schematic
Here’s that schematic, the only thing that needs to be done to convert the torch to single mode ON/OFF at full brightness, is to bridge out that FET.
Components Desoldered
To help save the extra few mA the IC & associated circuitry will draw from the battery, I have removed all of the components involved in the multimode control. This leaves just the current limiting resistors for the LED itself.
Jumper Link
The final part above, is to install a small link across the Drain & Source pads of the FET. Now the switch controls the LED directly with no silly electronics in between. A proper torch at last.
Following on from the teardown & analysis of the charger, here’s the torch itself under the spotlight.
LED Torch
Here’s the torch itself, it’s a sturdy device, made of aluminium. Power is provided by a single 18650 Li-Ion cell.
Charging Port
Here’s the charging port on the torch, there’s no electronics in here for controlling the charge, the socket is simply connected directly to the Li-Ion cell, and requires a proper external charger.
LED Pill
Unscrewing the lens gives access to the LED core, this also unscrews from the torch body itself, leaving the power switch & the battery in the body.
LED Module
Unscrewing the aluminised plastic reflector reveals the LED itself. Being a new device, I expected an XM-L or XM-L2 Cree LED in here, but it’s actually an XR-E model, a significantly older technology, rated at max 1A of drive current.
LED Back
Popping the control PCB out from the pill reveals a lot of empty space, but the back of the LED is completely covered by a heatsinking plate, which is conducting heat to the main body of the torch.
Control PCB
Not much to see on the control PCB, just a bunch of limiting resistors, and a multi-mode LED driver IC in a SOT-23 package. There’s no proper constant-current LED driver, and as the battery discharges the torch will dim, until the low voltage cutout on the cell turns things off completely.
In my previous post, I mentioned I’d be replacing the factory supplied charging gear with something that actually charges lithium chemistry cells correctly.
Charging Base
Here’s the base as supplied, with an indicator LED on the right hand side. This LED indicates nothing other than power being applied to the charging base. It’s just connected across the power input with a resistor. This also means that any battery left in the charger while it’s unplugged will discharge itself through this LED over time. Great design there China!
PCB Removed
Here I’ve removed the PCB – there’s no need for it to be taking up any space, as it’s just a complete waste of copper clad board in the first place. The battery tabs have been desoldered & hot snot used to secure them into the plastic casing.
USB Hole
The charger modules I use are USB powered, so a small hole has been routed out in the casing to allow access to the port.
Charging Module
Here the charging module has been installed & wired to the battery tabs. Output is now a nice 4.18v, and will automatically stop charging when the cell is full.
Safety has been restored!
A member of the family recently bought one of these torches from Maplin electronics, and the included chargers for the 18650 lithium-ion cells leave a lot to be desired.
Torch
Here’s what’s supplied. The torch itself is OK – very bright, and a good size. Me being cynical of overpriced Chinese equipment with lithium batteries, I decided to look in the charging base & the cigar-lighter adaptor to see if there was any actual charging logic.
Charger
Answer – nope. Not a single active component in here. It’s just a jack connected to the battery terminals. There’s all the space there to fit a proper charging circuit, but it’s been left out to save money.
OK then, is it inside the cigarette lighter adaptor?
Lighter Adaptor
Nope. Not a single sign of anything resembling a Lithium-Ion charger IC. There’s a standard MC34063A 1.5A Buck converter IC on the bottom of the PCB, this is what’s giving the low voltage output for the torch.
Charger Bottom
Here’s the IC – just a buck converter. The output voltage here is 4.3v. This is higher than the safe charging voltage of a lithium ion cell, of 4.2v.
The cells supplied are “protected” versions, having charge/discharge protection circuitry built onto the end of the cell on a small PCB, this makes the cell slightly longer than a bare 18650, so it’s easy to tell them apart.
The manufacturers in this case are relying on that protection circuit on the cell to prevent an overcharge condition – this isn’t the purpose they’re designed for, and charging this way is very stressful for the cells. I wouldn’t like to leave one of these units charging unattended, as a battery explosion might result.
More to come shortly when I build a proper charger for this torch, so it can be recharged without fearing an alkali metal fire!
I really like the UV-82s, over the UV-5Rs I was originally using, so I’ve bought another pair. Here are the power levels on test. Tests were done with a full battery charge on the 2m/70cm calling frequencies.
In my shack, 99% of my gear is all 12v powered, which is good for a few reasons:
Single Power Supply – This increases efficiency, as I’m only getting the losses of a single supply.
Safety – Mains voltages are dangerous, I’m not fond of working on such equipment.
Portability – I can power everything pretty much no matter were I am from a convenient car battery.
Convenience – Since everything is single supply, with all the same plugs, I don’t have to think about what goes where. This is more important due to my forgetfulness ;).
The one piece of equipment I regularly use that isn’t 12v is my soldering station. This is a Maplin A55KJ digital unit, which uses a 24v heating element.
While the soldering wand works OK when hooked direct to a 12v power supply (only at half power though), this removes the convenience of having temperature control.
The circuitry inside the unit is PIC microcontroller based, and doesn’t even bother rectifying the AC from the supply transformer before it’s sent to the heater. Because of this there are several reasons why I can’t just hook a DC-DC converter up to it to give it 24v.
It’s sensing the zero-crossing for the triac switch, to reduce heat dissipation, so it refuses to work at all with DC.
On looking at the Great Google, I found a project on Dangerous Prototypes, an Arduino based PID controller for soldering irons.
This requires that the soldering wand itself contains a thermocouple sensor – as the Maplin one I have is a cheap copy of the Atten 938D, it doesn’t actually use a thermocouple for temperature sensing. It appears to read the resistance of the element itself – Nichrome heating elements change resistance significantly depending on temperature.
I’ve managed to find a source of cheap irons on eBay, with built in thermocouples, so I’ve got a couple on order to do some testing with. While I wait for those to arrive, I’ve prototyped up the circuit on breadboard for testing:
Prototype
I’ve remapped some of the Arduino pins, to make PCB layout less of a headache, but the system is working OK so far, with manual input for the sensed temperature.
I’m using an IRL520N logic-level HEXFET for the power switching, rated at 10A. As the irons only draw a max of 4.5A, this is plenty beefy enough.
To come up with the +24v supply for the heater, a small DC-DC converter will be used.
More to come when the components for the thermocouple amplifier arrive, and the soldering irons themselves!
I often find myself carrying by go bag up to the boat during trips, so I can do some radio. However at 16lbs it’s a pain on public transport. A fixed radio was required! Another Wouxun GK-UV950P was ordered, and the fact that the head unit is detachable from this radio makes a clean install much easier.
Mounting Bracket
I found a nice spot under a shelf for the main radio unit, above is the mounting bracket installed.
This location is pretty much directly behind where the head unit is placed, but the audio is a bit muffled by the wooden frame of the boat & some external speakers will be required for the future.
Main Radio Unit
Here’s the main radio unit mounted on it’s bracket, with the speakers facing down to improve the audio slightly. I used the supplied interface cable for the head unit, even though it’s too long. I do have the tools to swage on new RJ-45s, but the stuff is a pain to terminate nicely & I really just couldn’t be bothered. So it’s just coiled up with some ties to keep it tidy. Main power is provided directly from the main DC bus. (880Ah total battery capacity, plus 90A engine alternator, 40A solar capacity).
Rat’s Nest
Here’s the main DC bus, with the distribution bars. With the addition of new circuits over the years, this has become a little messy. At some point some labelling would be a good idea!
Radio Face Plate
Finally, the head unit is installed in a spot on the main panel. It does stick out a little more than I’d like, but it’s a lot of very dusty work with the router to make a nice hole to sink it further in. All my local repeaters & 2m/70cm simplex are programmed in at the moment.
Antenna Magmount
I’ve got a Nagoya SP-80 antenna on a magmount for the radio, a magmount being used due to the many low bridges & trees on the canal. (It’s on the roof next to the first solar panel above). I prefer it to just fall over instead of having the antenna bend if anything hits it!
Part 2 will be coming soon with details of the permanent antenna feeder.
The latest addition to my radio shack is the GY561 frequency & power meter, which has already come in useful for measuring the output power of all my radios.
GY561
It’s a small device, roughly the same size & weight as a stock UV-5R. Power is provided by 3 AAA cells.
Display
The display is a standard HD44780 8×2 module. The display on this unit isn’t backlit, so no operating in the dark.
Cover Removed
The cover pops off easily to allow access to the internals, without having to remove any screws!
The 4 screws on the back of the unit hold the heatsink plate for the 50W 50Ω dummy load resistor.
Removing the cover reveals a couple of adjustments, for frequency & RF power calibration.
There are also 3 tactile switches that aren’t on the front panel. According to the manual (which in itself is a masterpiece of Chinglish), they are used to software calibrate the unit if an accurate RF power source is available. I will attempt to do a reasonable translation when time allows.
Disassembly further than this involves some desoldering in awkward places, so a search of the internet revealed an image of the rest of the internal components. In the case of my meter, all the part numbers have been scrubbed off the ICs in an attempt to hide their purpose. While it’s possible to cross-reference IC databooks & find the part numbers manually, this process is a time consuming one. Luckily the image I managed to locate doesn’t have the numbers scrubbed.
Total Disassembly
Under the LCD is some 74HC series logic, and a prescaler IC as seen in the previous frequency counter post. However in this unit the prescaler is a MB506 microwave band version to handle the higher frequencies specified.
In this case however the main microcontroller is an ATMEGA8L.
This is complemented by a SN54HC393 4-bit binary counter for the frequency side of things. This seems to make it much more usable down to lower frequencies, although the manual is very generous in this regard, stating that it’s capable of reading down to 1kHz. In practice I’ve found the lowest it reliably reads the frequency input is 10MHz, using my AD9850 DDS VFO Module as a signal source.
It did however read slightly high on all readings with the DDS, but this could have been due to the low power output of the frequency source.
Just like the other frequency counter module, this also uses a trimmer capacitor to adjust the microcontroller’s clock frequency to adjust the calibration.
The power supply circuitry is in the bottom left corner of the board, in this case a small switching supply. The switching regulator is needed to boost the +4.5v of the batteries to +5v for the logic.
Also, as the batteries discharge & their terminal voltage drops, the switching regulator will allow the circuit to carry on functioning. At present I am unsure of the lower battery voltage limit on the meter, but AAA cells are usually considered dead at 0.8v terminal voltage. (2.4v total for the 3 cells).
When turned on this meter draws 52mA from the battery, and assuming 1200mAh capacity for a decent brand-name AAA cell, this should give a battery life of 23 hours continuous use.
On the back of the main PCB is a 5v relay, which seems to be switching an input attenuator for higher power levels, although I only managed to trigger it on the 2m band.
Finally, right at the back attached to an aluminium plate, is the 50Ω dummy load resistor. This component will make up most of the cost of building these, at roughly £15.
On my DVM, this termination reads at about 46Ω, because of the other components on the board are skewing the reading. There are a pair of SMT resistors, at 200Ω & 390Ω in series, and these are connected across the 50Ω RF resistor, giving a total resistance of 46.094Ω.
This isn’t ideal, and the impedance mismatch will probably affect the calibration of the unit somewhat.
The heatsinking provided by the aluminium plate is minimal, and the unit gets noticeably warm within a couple of minutes measuring higher power levels.
High power readings should definitely be limited to very short periods, to prevent overheating.
The RF is sampled from the dummy load with a short piece of Teflon coax.
There’s a rubber duck antenna included, but this is pretty useless unless it’s almost in contact with the transmitting antenna, as there’s no input amplification. It might be handy for detecting RF emissions from power supplies, etc.
For the total cost involved I’m not expecting miracles as far as accuracy is concerned, (the manual states +/-10% on power readings).
The frequency readout does seem to be pretty much spot on though, and the ability to calibrate against a known source is handy if I need some more accuracy in the future.
I’ve also done an SWR test on the dummy load, and the results aren’t good.
At 145.500 MHz, the SWR is 3:1, while at 433.500 it’s closer to 4:1. This is probably due to the lower than 50Ω I measured at the meter’s connector.
These SWR readings also wander around somewhat as the load resistor warms up under power.
I’ll probably also replace the AAA cells with a LiPo cell & associated charge/protection circuitry, to make the unit chargeable via USB. Avoiding disposable batteries is the goal.
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