[sdiy] 7905 output voltage, FAQ probably

[Csaba Zvekan]

I've had just the same problem once with a 7805/7905 setup. I think  
the imbalance comes from the positive regulator using more current  
than the negative.
Try a voltage divider of 10K before the inputs . Also how big is your  
transformer ? Can we see your schematic ?

Csaba


On Feb 7, 2009, at 10:41 AM, Jason Proctor wrote:

> thanks for the response.
>
> i currently have a little circuit breadboarded up that has an opamp  
> sucking on it, and the output voltage is down to -5.7v, so it's  
> heading in the right direction. i fully expect the one that's  
> soldered in to start behaving itself when i hook it up to various  
> things.
>
> any idea why this affects only the -ve regulator? the 7805 i wired  
> up with nothing sucking on its output gave a reliable +5.
>
> tx
> j
>
>
>
>> You need to give them a minimal load to ensure good regulation. if  
>> not in circuit then stick an LED and resistor across the output to  
>> get it running. If in circuit then there is probably something wrong
>>
>> Best Regards
>>
>> (Mr) Laurie Biddulph
>> Phone: +61 (0)2 4340 0938
>> Mobile: 0400 257 645
>>
>> Elby Designs
>> ABN: 70 022 727 605
>> http://www.elby-designs.com
>
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