Boards about to be delivered and pictures of the prototype!
So I missed the DHL post this morning, but the boards are about to be delivered. In the meantime here are some pictures of the prototype board both before components were fitted and then with it working on the car.
First, this is the home etched PCB used to build the first on-car unit. As you can see the PCB tracks are relatively large as I can't do very fine etching with the equipment I have and also I can only do a single layer. The tracks are printed out with a laser printer and ironed on to the copper before etching, so very narrow PCB tracks can't really be done. This has the effect of making the PCB a bit larger so the properly manufactured parts will be a good amount smaller and they should fit inside the original case.
This second image is the fully built prototype. The cables out of the bottom are the power, ground, and signal wires. And out of the top is the thermocouple connection. Out of shot these are plugged into the standard loom connectors. I ripped the plugs out of a faulty CAT ECU to get it going, and that's the case I'm going to use to mount on the car for motion testing.
The unit is sitting on the green cloth because there is no insulation on the underside of the board to protect against short circuits. Clearly the car can't be driven like this; it's an idle-only test.
Power is being supplied by the car (12v nominal). The USB connector is feeding a real-time data feed into a laptop, giving the temperature of the exhaust gases as read from the thermocouple and the signal level the unit is generating for input to the main Montronic ECU. It's a happy coincidence that if you switch the ignition off with the laptop still connected, the 5v from the USB cable will continue to power the microprocessor, meaning you can continue to observe the temperature of the catalytic converters long after the engine is switched off.
Running temperatures at warm idle seem to be around 490-500 celsius. Pretty hot!
Next blog will be the empty boards and hopefully a fully assembled factory made PCB.