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ah should have guessed - āDont be scared to try itā =D
Cool ill put it on the list, seems fun.
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hey!
may be a stupid question but I would like to build mine this weekend and I donāt have the right capacitorsā¦
is it really important to have exactly the right values or can I put different ones without going too far from the starting values?
Enoha
no not super important! they should be fine to be honest. the 47pf could be anything really between 10pf and 100pf, and the 100nf same, I mean you could even not bother with em! it still works (without the 47pf it does show some weird behaviour where both of the output attenuverters seem to adjust each other, but you might like that haha). as for the 10uf same thing, power filtering you probably even be able to get away without them.
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Hi I just finished building mine and I tested it with a piezzo connected to a tensioned spring but I couldnāt get it to work.
in fact I have just a parasitic oscillation but nothing like the sound of the piezzoā¦
I tested with an oscillator at the input and I could hear it well at the output but when I cut the power supply to the module I got the same thingā¦ 
I donāt really understand how this module is supposed to work and especially how to use the different inputs and outputs?
thanks
enoha
hey enoha! so regarding the oscillation Iām not sure as I just tried what you tried and I dont get it. double check the solder joints especially on the 47pf capacitor.
regarding piezo function. the offset knob put that exactly central as this knob acts by offsetting the voltage, putting it in the middle means it doesnāt offset. then turn the boost to max.
plug in a piezo speaker, the GND black wire to the sleeve of a jack, and the red wire to the tip of the jack, and you should hear some sound! it should be quite loud. if it is oscillating maybe it is feedback from the speakers??? thats just a guess.
if you want even more gain increase the value of R5. which is at 100k, maybe pop in something like 1m ā¦
this will make it boost the gain by between 10 and 20 times, so taking into account you may want to increase R2 to 1M also.
I hope this makes sensE! but it should work with a piezo without any modifications.
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ok Iāll check all this but just one question: I donāt have a eurorack style power supply (I just use a +12v/GND/-12v) so I didnāt pay attention to the power supply part of the TL074. I have just powered it normally and I didnāt put the 100nf capacitors (c3 and c4) nor the 10uf capacitors (c1 and c2). I was wondering what they are used for? are they necessary?
yeah that should be fine!!! however maybe omitting the 100nf decoupling capacitors might cause the feedback? I really dont know!
but props to you! I fully approve of you skipping filtering capacitors haha. I never bothered adding before I made these proper ones, and I can safely say they have only improved situations a couple of times, but I guess these times are enough for me to just plonk em in :D.
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Hereās more than you need to know:
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And still more (warning: muntzing)
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@lookmumnocomputer will you make a vid on this one? I built it but dont really understand whats going on
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thanks a lot itās really complete! but at the beginning of his video (https://youtu.be/BcJ6UdDx1vg?t=239) when he explains that the circuit is not always soliciting, he explains that the input voltage changes (stop me if I misunderstood 
) this is the circuit activity but is it the same for the intensity?
yes it would be really good just to understand how it works and what we can do with itā¦
super I just checked my circuit and it came from my jacks which were badly connected to GND 
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Hi All, did Sam do a video on building the OBA #1171 and its features? I may be looking in the wrong place but canāt see on yet.
Hello @Slarteybartfast welcome here, and no i donāt think for OBA vid
only this page
Thanks Dud, just wanted to check to make sure I hadnāt missed it. If anyone has any additional photos of what it looks like built from the rearview so I can see how the two boards work together that would be a great help. Iām still a bit slow in following the schematics and have to rely on visual aids to help me get everything lined up. Iām a real novice but these projects are encouraging me to have a go anyway.
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Trust yourself and donāt hesitate to ask for help
For this module sorry iāve not make it, but maybe someone here.
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Thanks @twinturbo thatās really helpful