SV: Re: [sdiy] Power supply mystery....

[Karl Ekdahl]

The entire thing is running of +-5v, the schematic is
not fully finished yet since i'm still trying to
develop the circuit. Right now the 741, the input
stage and the FET to /WR (i wonder if that works btw.)
isn't even connected. The 4050 is completely turned
off, that is, all outs are positive so no sinking to
ground. 

All in all the circuit does run while using the small
zener supply but the voltage drops to about 4.5v and i
have huge groundspikes. I tried putting a transistor
as a current amplifier at the base of the zener, but
that worked even worse. It also feels strange to me
that this little circuit can have such an inpact on a
1A powersupply, that feels like it should be a
fail-safe way of testing the circuit before building
the actual supply.

Karl

--- Laurie Biddulph <elby_designs at ozemail.com.au>
skrev:

> Karl,
> Your schematic does appear to show power connections
> to the 2 main ICs nor
> the 741 opamp or 4050. Can you confirm what you have
> for these lines?
> Careful with the 4050 as the power pins are not
> where you would normally
> expect them.
> 
> Best Regards
> 
> (Mr) Laurie Biddulph
> 
> Elby Designs
> ABN: 70 022 727 605
> http://www.elby-designs.com
> 
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> ----- Original Message ----- 
> From: "Karl Ekdahl" <elektrodwarf at yahoo.se>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Thursday, September 01, 2005 9:22 PM
> Subject: [sdiy] Power supply mystery....
> 
> 
> > Hi list, i'm currently trying to update my old
> > bitcrusher but has run into some weird problems.
> >
> > I was going to build a tiny zener dual supply for
> it
> > but it seems the circuit draws too much power (the
> > voltage drops) allthough my readings says 30mA.
> While
> > connecting a 1A 7x05-based supply the voltage
> instead
> > *rises* to about 10V. The supply drops to +-5v
> again
> > if disconnecting the 0804 and the 4050. My guess
> is
> > that it, again, has something with too much (or
> too
> > little) power to do.
> >
> > I guess this circuit should draw <100mA but since
> i
> > don't really know how to calculate the whole thing
> i'm
> > not sure.
> >
> > I'm totally stuck on this, if anyone feels like in
> a
> > good mood, please take a look at the schematic
> > (http://www.cocospalme.se/niema/bitcrusher2.jpg),
> it
> > is all but impossible i've done something really
> > wrong...
> >
> > thanks
> >
> > Karl
> >
> 
> 
>