MS20 Filter on Stripboard LED question


Is the way I marked it right?

I hope I get a quick answer. I don’t dare to turn it on :worried:

yes it’s like that :slight_smile:

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Juchey !! Thx a lot !! So soldering is done and it´s ready for the first run :slight_smile:

Wish me luck

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maybe you know but don’t forget the Input jack GND, is not drawing on the schem :wink:


Thx have grounded all jacks and pots.

I´m really excited. It´s the third real module after your PT2399 Delay and the 3340 VCO


It’s a rather simple construction there is no reason that it does not work, good luck and may the force be with you
give us a report

Its not working :frowning: the two Leds are flickering for a second if i put the input in and they light up when the input jack touch the sleeve ring. and the op amp gets warm :frowning:

The LEDs used as clipping diodes in the resonance feedback path, so they only light up when you have enough resonance that things are clipping. The ICs getting warm is potentially a big problem, though – first step is to turn the power off, remove the ICs from their sockets, and use a multimeter to verify that you have the right supply voltages in the right place.

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Where can I see which voltage has to be where?

For voltages i think that @fredrik will be able to answer you, but otherwise beware of the position of the Hi / Low switch when you test your module, because depending on the position chosen the cut off pot reverses, and test also with a Triangle or a Saw wave form because the square can block it

Tested with Saw Triangle and Square .

The Jumper at the left BC558 goes to the middle leg. Is that right ?

I Also have a 5K Poti at the cutoff instead a 4.7k but i guess that is not the problem

yes, and for the pot it’s not important

maybe check all the components placement again and check your solder too

you don’t forget the cut under IC ?

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every traces are cutted. Here are Pics from the PCB maybe someone can see a mistake.

The BC558 are not new. I took them from another project, because i dont know if BC559 is okay too


you have inverted the power connection of the 3 wire at left
and there is a line under IC 1 normaly before the +12
suddenly it shifts components to the right

on your circuit : it’s the blue the GND ? white -12 and red +12 ?

so the bypass cap don’t connect +12 to GND and GND to -12
so the LM13700 pin 6 need to go to -12

the wire to the cut off pot are not good to (normaly red +12 and blue -12)

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What is a ligne ? I don´t understand?

And YES you are right, thank you so much ive inverted the Power Cables, what a mistake. So all i have to do is to correct the Power Cables ? Ahh think ive got it The GND and -12v must be under The +12 cable

no , you have a mistake , you have forgotten a line

on the schem the power wire don’t pass by the IC
it shifts a lot of things in fact

EDIT : LINE not ligne (in french) sorry

the +12 (red) begin 2 line under the IC (TL074), and we have the same color wire to the end of line power (for the cut off pot, and other components)

Oh shit, yes, so i have o build the whole shit new… :frowning:

sorry for you, yes I think you’re going to have to do another one, a little piece of advice I gave this morning, really take the time when you build a circuit

No! I just have to swap the GND Power cable under the red +12v Cable and the wihte under the GND and the blue Cable from The Cutoff Pot a line deeper.

Have a look again ! I think i don´t forgot a whole line