Parasit studio - Quantum Defrakulator help? CD4013 issue??

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tome.talevski
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Post by tome.talevski »

Just finished building the quantum defrakulator and it almost works.....



Its a 3 oscillator synth circuit with oscillator 1 turning into a 4 step sequencer when the LFO switch is pressed. All the oscillators work... the sequencer doesn't and neither does the switch for that matter. The switch doesn't do anything until randomly it might engage the sequencer for one step or so then reset back to the first and stay there.

When I mess about with the CD4013 I can get some movement... if I ground (with a probe) pin 1 and 8 (they're joined with a jumper) I get it moving through one cycle of the 4 step sequencer. When I ground pin 13 is moves back and forth between seq1 and seq 4.

The rate knob doesn't do anything however if I touch the lugs on the rate and and seq1 knob then I can hear the rate/lfo.

I've tried changing/removing the 1M resistor and 100n cap connected to the switch however that didn't make any difference at all. I've been reading about the bounce issue related to the CD4013 however can't really figure it out.. I suspect that's the issue here?

Any help would be much appreciated... its sounds fantastic.. if only it work exactly as it should! :)


Stripboard layout




build doc/schematic

https://www.parasitstudio.se/uploads/2/ ... om_doc.pdf


Build photo


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deltafred
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Post by deltafred »

For a start I would put a 100nF decoupling capacitor between 0v and 5v as close as possible to each IC.

With digital circuits putting a single 100nF cap somewhere on the board is not sufficient, each IC needs it's own decoupling cap as close as possible to the supply pins.

I would solder them on the back of the board directly to the socket pins (with sleeving on any bare leads).
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tome.talevski
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Post by tome.talevski »

Thanks deltafred.. so, connecting a 100nf cap to pins 0 and 5v on each IC?

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deltafred
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Post by deltafred »

tome.talevski wrote: 16 Aug 2021, 08:52 Thanks deltafred.. so, connecting a 100nf cap to pins 0 and 5v on each IC?
Yes, disc ceramic is what is normally used.
Politics is the art of so plucking the goose as to obtain the most feathers with the least squawking. - R.G. 2011
Jeez, she's an ugly bastard, she makes my socks hurt. I hope it's no ones missus here. - Ice-9 2012

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tome.talevski
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Post by tome.talevski »

nothing to see here... despite looking over everything a thousand times I maned to miss an unsoldered jumper end! Thank you again for taking the time to troubleshoot!

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