Resonance problem

I’ve got a problem with the resonance on the struthi. The resonance doesn’t do anything, I get no self oscillation. I’ve reheated the q point, what else should I look at?

first thing to check is make sure the 8pin connector between the two boards is making good contact on all pins (use DMM continuity test between the headers on each board), if you trimmed the Q lead a smidgen more than needed this can occur (I have done this myself before)

Maybe you could tell us which filterboard you use too !

sm4 mkII! I’ll check the pins I’ve reheated the 8 pin connecters on both boards

Is there anything on the filter board that could be broken? Soldering looks good. Everything is in the right place

Unless I’ve trimmed the q lead more than I should? Everything else is working fine

Let’s try a test…

Remove IC3. What is the current flowing between pin 1 and pin 6 of the socket when resonance is set to 0 and when it is set to 63?

When it’s set to 63 it has a voltage of around 1.02 and it’s -0.902 when set to 0 is this normal? I’m having to set the resonance and then remove the control board to get a reading

I am asking you to measure current; and you need to keep the two board connected (for example with wires) to do the test.

ok thanks i’ll get some wires what am I looking for when the resonance setting changes?

A change in current, from a few microamps (your meter might not detect it) when resonance is 0, to a small value (0.1 …1 mA range) when resonance is set to the maximum value.

K I’m gonna need to go out and buy another 8 pin connecter with wires to do this as I don’t have anything lying around to connect the wires to the pins. I’ll get back to you once I’ve got the part. Is it worth getting a new chip (or chips) in case they’ve gone?

You can as well solder some wires to the board… today is sunday and at least here in germany it will be hard to get an 8 pin arduino header somewhere in a store…

Yeah I’m gonna head to Maplin tomorrow I’ll report back later thanks


i have the same problem (
i made this test, the multimeter’s value doesn’t changed when the resonance 0 or 63 (result: 0.014 at 2000u).
is there a problem with the socket?

@Polymonsta: you have an older version of SMR4, so let’s not mix things up!

Ok I now have the 2 boards connected with jumper wires. I’m testing the current on the smallest setting on the voltmeter. It seems to fluctuate between 0 & 0.1 when the resonance is set on 0 and 63.

Just to double check - pin 1 is the bottom left, and 6 is 6 along from that clockwise

pin 1 is bottom right corner i mean and 6 is 6 along clockwise I mean! Is that correct?

Doesn’t seem to be any change when I adjust the resonance