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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
dual utility lfo wiring questions
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patchdub



Joined: Jan 21, 2009
Posts: 56
Location: Taos, NM

PostPosted: Wed Jan 21, 2009 1:25 am    Post subject: dual utility lfo wiring questions Reply with quote  Mark this post and the followings unread

hi. i am building my second modular, the cgs dual utility lfo, and have a few questions. these are probably obvious questions but i am a novice and struggling with the schematic.

on the cgs website i am guessing the diagram shows the pots from the underside and that i would just mirror the diagram on the pcb for the 2nd half of the lfo? if so i get confused when i look at the switches diagram because the purple wire goes to the ramp on the left side and the purple goes to the square on the right side. how do i orient the pots and wire them so i don't get some of them backwards?

also is LK the negative for the led?

and is using a 500k pot for the speed instead of the 100k recomended?

thank you
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andrewF



Joined: Dec 29, 2006
Posts: 1176
Location: australia
Audio files: 4

PostPosted: Wed Jan 21, 2009 7:21 am    Post subject: Re: dual utility lfo wiring questions Reply with quote  Mark this post and the followings unread

welcome Hi patchdub
i think Ken has shown the wiring connections with the point-of-view looking at the back of the pots, shafts pointing away from you.
The connections for the 2nd lfo do not necessarily mirror those of the 1st. One way to check is to examine the components the pots connect to. For example, in the wiring diagram, you can see the left side wire to the speed pot connects to a 4k7 resistor on the PCB. Checking the speed pot for lfo#2, the left side connection also goes to 4k7. This is an easy way to check if you are not sure.
Posted Image, might have been reduced in size. Click Image to view fullscreen.
You can do the same for the shape pots by checking the directions of the diode connected to the outer tabs.
So long as you get the pot's centre connection correct, it is not a disaster if the other two wires are switched....i do it all the time Laughing

Yes - LK is the cathode/negative of the LED, the shorter pin.

Wiring up the Vari pots and switches, is a bit trickier. don't worry about the colour of the wires - that is just to make the diagram clearer. If all the wires were drawn the same colour, the crossover points would appear as connections. Just remember the shafts of the pots are pointing away from you.

500k speed pot - I like slow LFOs and a good wide range so it suits me. You could do one LFO with 500k and the other with 100k and see which is good for you....or even put a bigger capacitor in one - increase the 47n to 100n for example.


have fun!
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patchdub



Joined: Jan 21, 2009
Posts: 56
Location: Taos, NM

PostPosted: Wed Jan 21, 2009 10:16 am    Post subject: Reply with quote  Mark this post and the followings unread

thank you so much for such a clear explanation! it makes some sense to me know. i am looking forward to soldering it up and trying it out. i think i will go with one 500k pot so i can compare. thanks!
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