[sdiy] Power supply mystery....

[Fredrik Carlqvist]

The ADC0804 outputs are TTL compatible, they can source about 6mA each.
When all the outputs are shorted to ground, they will draw 48mA at
least. You should have resistors on the outputs before swamping them to
ground. 

Try to set the bit depth control to '8' (disconnected, and see if your
PS can handle that... 


Fredrik C



> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl 
> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Karl Ekdahl
> Sent: den 1 september 2005 13:22
> To: synth-diy at dropmix.xs4all.nl
> 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
>