I ordered the controller print in China (JLCPCB) and after 10 days I received the print (5x). It looks beautiful, and I wanted to start soldering parts on it. I started with a few big parts to get a bit accustomed to the schematics and it worked well. Voltage regulators, Elco's, driver ic's, and the frequency measuring input circuit.

Time to do a first check. I measured the resistance between the Vcc and the ground, before putting 13.8 volts on it. It was zero Ohm. Not good,.......

I checked a second board and this board without any component on it, was also zero ohms,.......bug in the board,....

After checking the board with a microscope, I found out that the output connector of the fan was a pin through connector, but the pins were connected to the ground at the backside of the print. The holes were metalized through the board, and there were no islands around the pins.  So that was a bug. I drilled the holes a little bit and did make it sure that the connection was away.

Good, the zero resistance was gone,....

The freq counter input circuit

The input circuit starts with a signal shaper with the first inverter of the AC14d. It works OK, I tested it up to 15MHz, and it was still working. It should work until at least 30MHz for the 10m band, but I did not test it yet. Need my Marconi signal generator for it to test.

The rest of the circuit, using the other 5 inverters, is for shaping the count enable pulse for the counter (AC161d, enp, pin7), and the micro controller (pin16). Basically it is a low pass filter with clipping. It makes a nice and sharp dc signal when there is HF input. The AC161d is only counting when pin 10 and 1 are high. The count procedure starts when pin 10 and 1give a negative pulse. The counter gives a divided by 8 symmetrical pulse on pin 12. The negative pulse (clear pulse) is given by the micro controller, pin 1, PB0. I have tested it until 15MHz and it is working well.

 

On the backside only the connectors of the Fan and the three for the relays signals going to the other two pcb's.

On the front side, you see the green break out connectors for the external relays. The connector is a bit to big, I had to push the pins  a bit to get it soldered well.

So, the next time pick the correct connectors,.....

I was a bit afraid to solder SMD parts, so the freq counter/pulse shaper circuit is soldered with standard parts. Well, it works also, but it looks awful. So I ordered SMD parts to do the rest of the PCB. I bought also a lot of 220uH chokes, but they are to big also. I used them but it is also not very elegant,...anyway it works.

As you can see some SMD parts are already soldered on the board. If you use a lot of light and a magnifying glass, It is doable.

The micro controller will be pushed in a socket, which is not yet delivered.

Anyway, within a few days I will have all the parts and can finish the controller board.

 

The function of the rest of the scheme is pretty straight forward. In the middle the micro controller. At the left the freq counter circuit. On the right the little EEPROM and the opto couplers, and the RJ45 connector, which is connected to the cable, which is going to the serial  to USB board for the PC connection. The rest of the board is full of driver ic's for the relays, and Elco's to keep the voltage nice and flat.

Reason for so many of them is that you want to switch fast,....

 

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