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sompost
Joined: Aug 17, 2010 Posts: 58 Location: Switzerland
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Posted: Wed Feb 10, 2016 11:22 am Post subject:
Thomas Henry Circuits: Component specs |
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Hi all,
I'm strip-boarding a few TH circuits into a simple monosynth because ... why not? I've already built a VCO555 ( ), a VCF-1 and am now doing a dual VCA-1. I'm running a bit low on quality components, in particular capacitors.
What type of capacitors would you choose for those (ceramic) discs that are not used as decoupling caps? Are the types and values critical? Would you always use highest quality ceramic ones or will any crapacitor do? Can I substitute a good ceramic NP0 for a polystyrene or would you rather not?
Thanks!
Ralph _________________ Built: MFOS SLMS plus, SL Ultimate & Expander, 10 step seq; SLMS MkII; PAiA FatMan, Mutable-Instruments Shruthi-1; Jasper Wasp Clone
Building: Maddox MonoWave; Auduino; ASM-2; Minimoog Clone
Backlogging: MFOS 16 step seq; TH SN Voice; Takeda One Board Farm; Okita Vocoder; Page TR-9090; TH GM Voice, AY Voice |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Wed Feb 10, 2016 5:25 pm Post subject:
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If Thomas lists a cap as a ceramic disc, I would take that to mean it's not very critical. Most of the critical ones in his circuits (at least off the top of my head anyway) are film caps.
Personally I try to buy C0G ceramics most of the time, but that doesn't always happen. But I don't buy disc caps at all in ages, if I'm not getting C0G I'll get MLCC ceramics for most "good enough" applications. |
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AlanP
Joined: Mar 11, 2014 Posts: 746 Location: New Zealand
Audio files: 41
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Posted: Wed Feb 10, 2016 11:46 pm Post subject:
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If you don't hugely care about being in tune, it's amazing what you can get away with in terms of component quality. (To a point, then you start getting to "do I care about this s***ing the bed in a few years?") |
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sompost
Joined: Aug 17, 2010 Posts: 58 Location: Switzerland
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Posted: Thu Feb 11, 2016 12:30 am Post subject:
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I don't usually buy discs either. I assumed "disc" to mean "ceramics", anyway.
I was asking because TH usually lists all resistors as 5% ones, instead of the 1% ones that everybody else recommends. So my reasoning was that his circuits seem to be resilient enough so as not to rely on very tight component specifications.
Still, I tend to buy high quality ceramics for all non-decoupling caps. But I'll try using those that I have for now, fingers crossed.
Thanks, elmegil. You're the best! _________________ Built: MFOS SLMS plus, SL Ultimate & Expander, 10 step seq; SLMS MkII; PAiA FatMan, Mutable-Instruments Shruthi-1; Jasper Wasp Clone
Building: Maddox MonoWave; Auduino; ASM-2; Minimoog Clone
Backlogging: MFOS 16 step seq; TH SN Voice; Takeda One Board Farm; Okita Vocoder; Page TR-9090; TH GM Voice, AY Voice |
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Grumble
Joined: Nov 23, 2015 Posts: 1294 Location: Netherlands
Audio files: 30
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Posted: Thu Feb 11, 2016 12:32 am Post subject:
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I would say: check which resistors/capacitors are used for timing purposes (eg. in an oscillator or filter the C's or/and R's that are responsible for the frequency response) should be of high quality in terms of temperature stability and value.
C's used for decoupling power supply are not critical in terms of value, but are critical impedance wise. |
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sompost
Joined: Aug 17, 2010 Posts: 58 Location: Switzerland
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Posted: Thu Feb 11, 2016 12:57 am Post subject:
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Thanks, Alan and Grumble.
You both appear to support elmegil's point: where it matters, TH's circuits list film capacitors (polystyrene in case of the VCF-1). So I'll use those -- and then use whatever shoddy pieces I have lying around for discs/ceramics and keep my fingers crossed.
I don't necessarily need perfect in-tune-ity (is that even a word?), but I also don't want a poor choice of components ruining my impression of an otherwise brilliant circuit.
Ralph _________________ Built: MFOS SLMS plus, SL Ultimate & Expander, 10 step seq; SLMS MkII; PAiA FatMan, Mutable-Instruments Shruthi-1; Jasper Wasp Clone
Building: Maddox MonoWave; Auduino; ASM-2; Minimoog Clone
Backlogging: MFOS 16 step seq; TH SN Voice; Takeda One Board Farm; Okita Vocoder; Page TR-9090; TH GM Voice, AY Voice |
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