[sdiy] LM13700 as VC resistor

Quincas Moreira quincas at gmail.com
Sun Feb 9 02:43:43 CET 2020


Of course, Jfets! I may be wrong but I think you get a bit of distortion of the original signal. Ray Wilson used one as a VCA in the Noise Toaster:

http://musicfromouterspace.com/analogsynth_new/NOISETOASTER/NOISETOASTER.php

Sent from my iPhone

> On 8 Feb 2020, at 19:35, Adam Inglis (sdiy) <synthdiy at adambaby.com> wrote:
> 
> What about a FET?
> 
> page 124 second edition Horowitz and Hill
> 
> low parts count!
> 
> A
> 
>> On 9 Feb 2020, at 4:08 am, Quincas Moreira <quincas at gmail.com> wrote:
>> 
>> You can tune the LED brightness and use parallel resistors to get lower resistances as needed, but yes, LDRs are a bit slow to respond, so if you need high speed they are not ideal.
>> 
>> 
>> Sent from my iPad
>> 
>>>> On 8 Feb 2020, at 11:46, Didier Leplae via Synth-diy <synth-diy at synth-diy.org> wrote:
>>> 
>>> In my experience vactrols seem a bit hard to control and the resistances are very high. 
>>> 
>>>>> On Feb 8, 2020, at 11:39 AM, Michael Zacherl <sdiy-mz01 at blauwurf.info> wrote:
>>>>> 
>>>>> On 08.02.2020, at 18:04, Quincas Moreira <quincas at gmail.com> wrote:
>>>>> 
>>>>> Here's the simplest VC resistor you can make, much easier than using an OTA!
>>>>> https://youtu.be/8BOnvSQpoGY
>>>> 
>>>> at the cost of speed, alas. 
>>>> m.
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