I have assembled the MK125 kit, but when I connect my 12VDC supply to it nothing happens. I connected the supply only with the PCB pins and I didn’t use the power jack, so my question is will it work if you only use the PCB pins or do you have to use the Power jack connection to supply the kit with 12V ?
It should work fine when you connect to the PCB pins. Check for continuity, direction of the IC and diodes etc…
Then I have a problem. I checked the polarity of the capacitors and the diods, etc. they are just fine. Then I measured the pins on the IC and pin 14 gives 10.80V, normally the relay must switch then but it doesn’t, I changed the transistor and I had the same result (no result).
And I removed the LDR and made a bypass and nothing happens pin 14 gives always 12V (±) no matter what I do, even when I turn the potmeter.
Apparantly you have two problems:
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pin 14 is high, but the relay does not activate
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pin 14 never changes state, so there must be a problem in the comparator circuit.
Are you sure the IC is not defective due to inverse mounting ?
Try shorting the two outer pins of the transistor, the relay should energize.
Next, remove the IC and apply +12VDC to pin 14. Once again the relay should energize.
Check if voltage on pin 13 can be adjusted from 0 to 12VDC by turning RV1
I found it, I didn’t put the power jack on the print and that’s why I didn’t had a GND. But now the led is lighting up and when I turn the potmeter to the “moon” side then it’s going out. If I take a flashlight and let it shine on the LDR then nothing happens, the LED isn’t lighting up.
It’s the same if the LED lights up and then when I put my hand over the LDR, it’s not going out.
How long is the delay (probably the time that the elco iss charged) ? I have hold it a couple of minutes.