[sdiy] ASM1-VCO Problem

[Magnus Danielson]

From: Jaco Sloof <jacosloof at yahoo.com>
Subject: Re: [sdiy] ASM1-VCO Problem
Date: Thu, 21 Aug 2003 13:23:18 -0700 (PDT)

> Hello Michiel and List,
> 
> I've built an ASM-1 VCO on stripboard myself, had problems with that 1 too..
> Its the LM311 pin 1. It goes to -15V
> 
> After that, I think it'll happily oscillate if the schem is followed correctly.
> 
> I hope this helps!

This "flaw" has a special history to it.

Oh, I better give it upfront - YES! It is MY fault!

If you have Genes schematics you will find it correct there, so no sched of
darkness over him here!

OK, when I did the schematics on the webpage I didn't have a schematic CAD
worth breathing about. So, what does a reasnoble and sensible man do? Scan
them! OK, so we have established that this is exactly what I didn't do.
I didn't have a (working) scanner. No, I did the logical thing - hacked them in
Postscript!

So, I built a library of components, resistors, capacitors, transistors, FETs,
diodes, op-amps etc. but what I didn't do was a propper LM 311 symbol... lazy
me! So I cheated out on my first schematic - the VCO schematic.

Sure, I could go and fix it... it on my "to fix list" among about 4711 other
equally important things to fix. However, it seems people have been able to
figure this flaw in the schematic out fairly quickly - you can do like I did
it and consider it another power-pin.

Many people have used this flawed schematic and made their own PCBs (or
whatever) and got it right, so it has slipped down on my list over the years.

Maybe I should make an effort and open the casebook on this again...

Interestingly, I have yeat to see a schematic CAD that works as well on
layouting symbols as well as the stuff I cooked up in Postscript some 5-6 years
ago. Actually that is more of a disapointment than a lame attempt to boost my
morale (I don't think I have one to strengthen to start with... haven't seen it
around lately...).

Anyways, cherio!
Magnus