[R-390] OT: Pass Transistor Question

[rbethman]

Barry,

With just ONE of those rectifiers, you don't need pass transistors for 
the power level you want.  You just need ONE decent 15VDC computer grade 
cap on the output!

You  "may" want to put a multi-meg ohm resistor across the big smooting 
cap so IF you reach in to work on it you don't get either a tool or 
yourself bit!

Bob - N0DGN

Barry wrote:
>> Hi
>>
>> Was the transformer designed for rectifier service?
>>
>> If it's a filament transformer, be sure to use diodes with  
>> significantly higher voltage ratings than "needed". Filaments don't  
>> much care about a voltage spike as you turn off the switch. In fact  
>> the inductive flyback doesn't generate a voltage spike on a 
>> filament.  Rectifier diodes *do* care about voltage spikes....
>>
>> Bob
>
> Well, that's a good question.  The transformer is a pull from (I 
> believe) a medical application that was apparently never used.  It has 
> dual primaries for 120/240V input, a single output winding at 19V @ 
> 7.2A, a tap at 11.4V @6A and another tap at 13.8V @6A.
>
> Just for the fun of it, I happened across a great deal on 4 stud-mount 
> rectifiers that can handle 12A, 300V.  While I didn't really need that 
> much "rectifier", I wanted to make it hefty.
>
> Thanks,
> Barry
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-- 
Bob - NØDGN