Re: power supply 2


"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.

ken


.

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