JFETs in ASM-1 VCO

Magnus Danielson cfmd at swipnet.se
Tue Nov 2 22:22:43 CET 1999


From: "Caloroso, Michael E" <CalorosoME at corning.com>
Subject: RE: JFETs in ASM-1 VCO
Date: Tue, 02 Nov 1999 13:37:36 -0500

> There are two approaches to discharging a cap,
> 1) short the cap terminals ala the FET switch, or
> 2) apply a voltage to the charged side ala the BJT, IE if the cap charges
>    from ground to a positive voltage, then reset the cap by applying ground
>    to the charging end.

These sound basically equalent in my ears... but there is another method:

Apply a high discharge current to the capacitor. This is another way to reset
the capacitor. If you charge the capacitor to positive values over ground, then
hooking a transistor to negative supply voltage and enabling it during a short
moment will reset the capacitor pretty quick. The obvious trouble is to ensure
that the capacitor doesn't get loaded to a too low level.

Cheers,
Magnus



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