[sdiy] Powersupply question

[Seb Francis]

Harry Bissell Jr wrote:

>--- Seb Francis <seb at burnit.co.uk> wrote:
>
>  
>
>>One other point: it can be a good idea to have a
>>diode on the output of 
>>each regulator, between the GND and VO, to protect
>>the regulator (and 
>>tantalum caps) against reverse voltage (obviously
>>put the diode round 
>>the way it won't conduct in normal circumstances!)
>>    
>>
>
>
>Add another diode with the cathode to the input pin
>and the anode to the output pin. If the main filter
>cap should suddenly go to ground (usually this is the
>biggest cap in the circuit so usually it discharges
>slowly)... the regulator can be reverse-biased by the
>capacitors on the regulator output (and your whole
>circuit).  
>
>  
>

.. these diodes are shown already in the schematic - that's why I didn't 
mention them (I only mentioned the protection diodes that I left out :)

http://burnit.co.uk/sdiy/PSU.gif