What could be wrong?

[diego]

I haven't found any 40106 yet but will keep on searching. Might very well find some ceramic ones.

Measured with a multimeter across the 40106 and it gets 5 volts. All the soldering looked spotless. Since it worked fine (but with very low sensitivity) for a while and then during tweaking went silent.. I guess some component must have given up for good.

As I understand it the other ICs are for output and voltage regulation only?

[sinclairuser]

have you used sockets or hard soldered the chips?, could be a mechanical contact issue.

[diego]

Sockets

[sinclairuser]

try pulling them out and putting back in, replacements may help, when its done and working get rid of the sockets and hard solder the working chips in place, and make sure to clean any flux off the board.

[diego]

Okay so I found a ceramic 40106 to replace with but still have the same problem. Any more ideas?

All the ICs get 5volts supply and the output looks perfect. Its the input signal that just flickers on the oscilloscope...could it possibly be the big transistor closest to the coil? Seems unlikely however that a transistor that big would give up

[diego]

Tested with different 40106 and they all worked a bit different, definitely showcasing the importance of testing different ones

When I turn on the circuit the input signal on pin6 is perfect, but approx 1 second later it starts to flicker. Could it be the 7660 not giving the right voltage? Got mad and ordered replacements for all the ICs from ebay now. If it doesn't do the trick it's going in the bin