[sdiy] The never ending ASM-1 VCO troubles :-)

[Magnus Danielson]

From: Neil Johnson <nej22 at hermes.cam.ac.uk>
Subject: Re: [sdiy] The never ending ASM-1 VCO troubles :-)
Date: Thu, 23 May 2002 21:26:37 +0100 (BST)

> Flo,
> 
> > VCO works perfectly (absolutely stable, with a great usable range) but the
> > OTHER ONE swings at ~30kHz (which is not much influenced by the control
> > voltage).
> 
> Check the reset transistor is connected correctly -- I had a similar
> experience with my VCO, only to find that the reset transistor was
> connected thw wrong way (pinout error on PCB), such that the LM311 was
> feeding current into the capacitor...Doh!!  Fixed it, works a treat.

Actually, the PCB is correct - put only if you use the PN4391 and not
the 2N4391. I think I put that one on the web.

It took a carefull look at the PCB and the datasheet to figure out.

Cheers,
Magnus