[Milsurplus] WTB Manuals and Power Supply Question

[John Schmitz]

Absolutely, we are on the same page. Love that basic electronics stuff. Good
point about the high load current due to faulty circuit components (leaky
decoupling caps etc) causing high ripple and hum and being mistaken for
needed additional filter capacitance. Bet that misunderstanding is made a
lot.

John


-----Original Message-----
From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net]On Behalf Of Unserviceable but
Repairable
Sent: Thursday, September 30, 2004 11:17 AM
To: cjs004 at comcast.net
Cc: milsurplus at mailman.qth.net
Subject: RE: [Milsurplus] WTB Manuals and Power Supply Question

John it looks like we sed same.  Fr'instance
u sed (kinda)

> it seems from memory that as load drops, so too does ripple

& I 1st sed

> ...and the C oughta be picked to deliver load V within ripple-limits
     between rectifier pulses.

If it does it for full load, it'll sure give lower ripple @ less load

The decay's given by

               -t/RC
    V = Vp X e

Where t, give or take, is near .5 the peak spacing.  So as RC gets bigger
the drop decreases to nothing.

And why if there's a near B+ short lotsa hum results.  An often-missed
consequence leading to unneeded filter cap. change-out
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