February 2011 – Experimental Engineering

Posted on February 28, 2011February 10, 2011 by The Engineer — Leave a comment

Sanyo Talkbook VAS

Here is a Sanyo tape recorder, with built in voice activation. Takes standard audio cassettes.
Here visible is the speaker on the left, microphone is on the right of the tape window. The tape counter is at the top.

Back cover removed from the unit, showing the PCB & the connections. The IC is the controller/amplifier.

Top of the PCB, control switches, volume potentiometer & microphone/headphone sockets on the right. DC power jack top left. Switch bottom centre senses what mode the tape drive is in.

Rear of the tape deck, main drive motor is bottom right, driving the capstan through a drive belt. This drives the tape spools through a series of gears & clutches. Belt going to top left drives the tape counter.

Front of the tape drive. Read/write head is top centre. Blue head is bulk erase head used during recording.

Main speaker. 8Ω 0.25W.

Simple mechanical tape counter.

Posted on February 26, 2011February 10, 2011 by The Engineer — 1 Comment

Combo Microwave

Here are the internals of a cheap Microwave/Convection Oven combo. Electronics bay is pretty much the same as a standard microwave, with the magnetron, transformer & diode/capacitor voltage doubler, with the addition of an extra fan & a pair of nichrome elements to provide the convection oven function.

Convection blower which keeps the cooking vapours & smoke away from the elements, & circulates the hot air around the cooking chamber. This is a 12v DC centrifugal type blower.

The elements are inside this steel shield, air duct extends from the centre.

This oven has a pair of thermal switches on the magnetron.

The usual capacitor/diode voltage doubler in the magnetron power supply. The transformer is visible to the left.

Electronic controller PCB. This has a pair of relays that switch the elements & the magnetron transformer.

Posted on February 24, 2011February 10, 2011 by The Engineer — Leave a comment

PCMCIA Ethernet Card

An old Xircom Ethernet card for a laptop. This uses the old 50 pin PCMCIA interface.

Rear of the card with the MAC address & card spec details.

PCB removed from the outer shield. Xircom ethernet chipset centre. Special socket on the right fits a RJ-45 adaptor lead.

Posted on February 22, 2011February 10, 2011 by The Engineer — Leave a comment

Grand Hand View

This is an adaptor to convert computer VGA to composite & S-Video output for a normal TV.

Bottom of the unit with option select switch.

PCB removed from the casing, CPU in centre, buffer RAM on the right.

Reverse side with the VGA connections at the top & the S-Video/composite outputs on the bottom.

Inputs. USB connector provides power, pair of VGA connectors provides passthrough function.

Outputs. Standard S-Video on the left & composite video on the right.

Posted on February 20, 2011February 10, 2011 by The Engineer — Leave a comment

Garmin eTrex

Pocket sized GPS navigator. Here is shown the greyscale dot matrix LCD.

Serial interface on the back of the unit. Pinout from left is +3v, Rx, Tx, GND.

PCB Removed from the casing. RTC backup battery in the centre of board, CPU & flash ROM on the left. GPS chipset is under the shield on the right.

Front of the PCB, GPS antenna on the right, LCD panel left.

LCD folded back from the PCB. Driver IC can be seen attached to the ribbon.

LCD Panel backlight. Requires 200v AC at 20kHz to glow green.

GPS chipset with the shield removed.

Posted on February 18, 2011February 10, 2011 by The Engineer — Leave a comment

Kidde Smoke Alarm

Old type ionization smoke alarm. Top of the device with the test button & sounder.

Bottom of the device. Battery compartment in centre.

Internals of the smoke alarm. Main component visible is the Ionization chamber.

Piezo sounder on inside of the top.

Inside the Ionization Chamber. 1µCi Americium-241 alpha particle source in the centre.
The radiation passes through the chamber, between the pair of electrodes, ionizing the air & permitting a small current to pass between the electrodes.
Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and interrupts this current, setting off the alarm.

Controller IC beneath the chamber.

Posted on February 16, 2011February 10, 2011 by The Engineer — Leave a comment

IDE Zip Drive

An old IDE interface Zip drive. This fits in a standard 3.5″ bay.

Top cover removed from the drive, IDE & power interfaces at the top, in centre is the eject solenoid assembly & the head assembly. Bottom is the spindle drive motor.

Head assembly with the top magnet removed. Voice coil is on the left, with the head preamp IC next to it. Head chips are on the end of the arm inside the parking sleeve on the right. Blue lever is the head lock.

Controller PCB removed from the casing.

Spindle motor. This is a 3-phase DC brushless type motor. Magnetic ring on the top engages with the hub of the Zip disk when insterted into the drive.

Magnets that interact with the voice coil on the head assembly.

Head armature assembly removed from the drive. The arm is supported by a pair of linear bearings & a stainless steel rod.

Posted on February 14, 2011February 10, 2011 by The Engineer — Leave a comment

Belling Microwave

Here is a cheap no frills microwave oven, which died after a few weeks of normal use.

Cover removed, showing the internals. Front of the microwave is on the left.

Closeup of the timer unit. Cheap & nasty.

Magnetron removed from the oven. Antenna is on the top, cooling fins visible in the center. White conector at the bottom is the filament terminals.

Chokes on the magnetron’s filament connections. These prevent microwave energy from feeding back into the electronics bay through the connections.

Magnetron cooling fins, tube & magnets removed from the frame.

Bare magnetron tube.

This PCB does some rudimentary power conditioning, power resistors are in series with the live feed to the power trasformer, to prevent huge power up surge. When the transformer energizes the relay, which is in parallel with the resistors, switches them out a fraction of a second after, providing full power to the transformer.
Standard RFI choke & capacitor at the top of the board, with the input resistor.

Power transformer to supply the magnetron with high voltage.
Power output is ~2kV at ~0.5A. Pair of spade terminals are the low voltage filament winding.

HV Capacitor. This along with the diode form a voltage doubler, to provide the magnetron with ~4kV DC.

HV diode stack.

Internals of the HV fuse. Rated for ~0.75A at 5kV. The fuse element is barely visible attached to the end of the spring. Connects between the transformer & the capacitor.

Cooling fan for the magnetron. Drive is cheap shaded pole motor.

Fan motor. Basic 240v shaded pole induction type.

Posted on February 12, 2011February 10, 2011 by The Engineer — Leave a comment

iPod

Old iPod with damaged screen. Here is the front with the Click Wheel.

Cover removed from the back, here the HDD is the biggest visible part.

Back cover removed from the unit, here is the back of the screen & the main PCB.

Back cover with the battery & headphone jack PCB.

Closeup of the Li-Ion battery.

Front removed from the unit, the touch sensitive Click Wheel PCB is folded away from the mainboard here.

Tactile switches underneath the Click Wheel.

1.8″ hard drive. Toshiba MK3008GAL.

Posted on February 10, 2011February 4, 2011 by The Engineer — 1 Comment

Hauppauge WinTV USB

Here is one of the first USB tuners that was available from Hauppauge Computer Works. Totally analog tuner of course, this model required 2 cables – a USB interface & a sound cable for the audio output of the tuner.

A/V connections.

For those who are interested. Here is the label with the model details.

Connection to an external antenna.

Bottom of the PCB.

Top of the PCB showing the USB interface IC (top left), cache memory (top right) & the main tuner assembly.

Posted on February 8, 2011February 4, 2011 by The Engineer — Leave a comment

Hot Laminator

Here is a cheap no brand hot laminator. This pulls the paper, inside a plastic pouch through a pair of heated rollers to seal it.

Top removed, heater assembly visible. PCB attached to the top cover holds LEDs to indicate power & ready status.

Here is the thermostat & thermal fuse, the thermostat switching the indicator on the front panel to tell the user when the unit is up to temperature. This has a self regulating thermostat. Thermal fuse inside the heat resistant tubing is to protect against any failure of the heater.

5 RPM motor that turns the rollers through a simple gear system.

Posted on February 7, 2011February 4, 2011 by The Engineer — Leave a comment

Xbox 360 HD A/V Cable

Teardown of the Xbox 360 HD A/V cable. Standard Xbox connector on the left. Component video/audio/composite video connectors on the right.

Internals of the Xbox connector. Black unit is fiber optic audio connector, PCB underneath holds the HD/SD video switch.

Posted on February 6, 2011February 4, 2011 by The Engineer — Leave a comment

Window Break Alarm

Cheap unbranded window break alarm. Here is the front of the unit, with the sounder at the top, Power/sensitivity switch at the right. Battery test button at the left.

Rear of the device, with the adhesive pad used to attach it to a window.

Front cover removed, showing the batteries, PCB & the sounder.

PCB removed from the casing, showing the remaining components.

Posted on February 5, 2011February 4, 2011 by The Engineer — Leave a comment

4Warn Carbon Monoxide Alarm

This is an old CO alarm, which was totally dead, having been connected to the wrong PSU.
Here is the front of the unit, with the Test button & indicator LEDs.