Re: power supply 2

On Mon, 17 Jul 2006 19:40:52 -0400, in message
<e9h75u$r0b$1@xxxxxxxxxxxxx>, "Ken O" <lera@xxxxxxxxx> scribed:


"Ken O" <lera@xxxxxxxxx> wrote in message news:e9h5rm$jh4$1@xxxxxxxxxxxxxxxx
HI,

I am working on a power supply. The transformer is getting hot after 30
minutes of use. I can touch it , but not more then a few seconds in a row.
I guess this is because of too much current.??
I use a 120v to 25v AC transformer, to a Bridge rectifier, then to a
2000uF 110 v capacitor . This capacitor is then discharge through a
transistor, with a timer at 2% duty cycle to its base. The transistor too
get very hot, hotter then the tranformer.
The following is the rest of the circuit.
Should I be adding a resistor to decrease the current ?



|
o------o||o--------o
| | |
o |
.------------. | o
| | |/ ---
| Timer |-| ---
| | |> o
| | o |
'------------' | |
| |
| |
o---------o---------o
|
o
ground
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


By the way, if the output is 25v, and the resistance of the coil in the
secondary is 2 Ohm, does that mean I am pulling 12 amps on the secondary ??
if so no wander its getting hot, but the transformer is rated 2 Amp.

The coil resistance is irrelevant, or at least it should be, because the
transformer should be seeing only AC current. The current must be deduced
by calculation of the parameters of the circuit after the rectifier. The
schematic you've included does not show what is going on; I can't make any
sense of it. Could you try to be a little more specific about your circuit
description?

--
Love is like a dying ember
And only memories remain
And through the ages I'll remember
Blue eyes cryin' in the rain
.

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