It’s well known that there are two versions of the 701 type controller available for Eberspacher heaters, the version with the blue logo is the official un-restricted model, while the version with the white logo is a version built for BT that restricts the heater to 1 hour runtime & has no diagnostics built in.
As these devices are microcontroller driven, I assumed that the hardware would be the same, only the code running in the micro being the bit that Eberspacher changed. This option would certainly have been the lowest cost.
Here’s the PCB removed from the plastic housing. There are definitely some differences that I can tell. As the un-restricted version has an extra wire for the diagnostic serial interface, and this board has no unpopulated parts, the PCB is definitely a different version.
In the centre is a Microchip PIC16C622 microcontroller, the OTP version in this case for cost reductions. (I may try reading the binary from this chip in the future, chances are it’s code protected though).
Below the micro is an NXP PCF8577C 32-segment LCD controller, this has an I²C interface to the PIC.
The temperature control function on these heaters is done via applying a resistance to one of the control lines, between 1750Ω-2180Ω, ±80Ω. (Very odd values these, not to mention no standard components can create this range easily, bloody engineers >_<). This is accomplished in hardware with a BU2092F I²C shift register from Rohm, which is connected to a bank of resistors. The microcontroller will switch combinations of these into the circuit to get the range of resistances required.
The rest of the circuit is local power regulation & filtering.
There’s not much on the other side of the PCB, just the LCD itself & the contacts for the buttons.
This is an old cordless landline phone, with dead handset batteries.
Here’s the handset with the back removed. Shown is the radio TX/RX board, underneath is the keyboard PCB with the speaker & mic. All the FM radio tuning coils are visible & a LT450GW electromechanical filter.
Radio PCB removed from the housing showing the main CPU controlling the unit, a Motorola MC13109FB.
The keypad PCB, with also holds the microphone & speaker.
Bottom of the keypad board, which holds a LSC526534DW 8-Bit µC & a AT93C46R serial EEPROM for phone number storage.
Here’s the base unit with it’s top cover removed. Black square object on far right of image is the microphone for intercom use, power supply section is top left, phone interface bottom left, FM radio is centre. Battery snap for power backup is bottom right.
PSU section of the board on the left here, 9v AC input socket at the bottom, with bridge rectifier diodes & main filter capacitor above. Two green transformers on the right are for audio impedance matching. Another LT450GW filter is visible at the top, part of the base unit FM transceiver.
Another 8-bit µC, this time a LSC526535P, paired with another AT93C46 EEPROM. Blue blob is 3.58MHz crystal resonator for the MCU clock. The SEC IC is a KS58015 4-bit binary to DTMF dialer IC. This is controlled by the µC.
Underside of the base unit Main PCB, showing the matching MC13109FB IC for the radio functions.
This is the Current Cost CC128 Real Time Power Meter. Shown here is the display unit, British Gas issued these free to some customers.
This unit measures current power draw in Watts, cost of power currently being used (requires unit price to be set), overall kWh usage over the past 1, 7 or 30 days & power trends during the day, night & evening. Also displays current time & current room temperature.
Here the front panel of the display has been un-clipped. At the bottom are the RJ-45 serial port & power connections.
This unit uses a PIC micro-controller as it’s CPU (PIC18F85J90) Just above & left of the CPU is the 433MHz SPD radio receiver module. The chips on the right of the CPU are a 25LC128 SPI serial EEPROM for data storage & a 74HC4060 14 stage binary counter, to which is connected the 32kHz clock crystal. The red wire around the top of the display is the antenna for the radio receiver.
For more info on the CC128 in general, the serial port & software for computer data logging, see this link
See this link for Current Cost’s list of software
Closeup of the ICs on the mainboard.
Here we have the transmitter unit, with Current Transformer (CT). The red clamp fits around one of the electric meter tails & read the current going to the various circuits. This unit is powered by 2x D cells, rated at a life of 7 years.
The PCB inside the transmitter. Again very minimal design, unknown controller IC, 433MHz radio transmitter on right hand side with wire antenna. Two barrel connectors on left hand side of board allow connection of up to two more CT clamps for measurement of 3-phase power. Centre of board is unmarked header. (ICSP?)
CT unit. Inside is a coil of wire & an iron core which surrounds the cable to be measured.