[sdiy] LM13700 as VC resistor

Matti Palm matti.palm at gmail.com
Sat Feb 8 19:25:09 CET 2020


Feedback modules has made a filter with the h11f1. 

https://feedback-modules.myshopify.com/collections/diy-kits/products/lpfet-vcf-diy-kit1

I tried to use it in a mute circuit without luck. I don’t remember why I didn’t like it. 
/matti

> 8 feb. 2020 kl. 19:04 skrev music.maker at gte.net:
> 
> 
> 
> This has been bugging me because I seem to remember a thread here years ago.  I can't
> remember what the outcome was, but maybe a search of the archives (for which I seem to have
> no foo) might find it.  I do remember it was regarding the datasheet circuits mentioned by
> the OP.  Generally, the feel I think was that under the right circuit circumstances, it can
> work like a VCresistor.  I remember that the vactrol was compared and is known to work
> properly as a floating VCresistor albeit slow to change value.  Not an EE here, but looking
> at the floating resistor circuit I see two current producing electrodes posing as a
> floating resistor.  I think generally the statement about it's lack of use in synth
> circuits is due to it not being very good is probably correct.  Looking at the single ended
> circuits, they are AC coupled...
> 
> Has anyone experience with H11F1 devices?  Those should be a lot faster than vactrols,
> probably more consistent, but I don't know if the transfer function is useful in
> audio/synth circuits.
> 
> -- ScottG
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