why my transfomer is heating too much
I have made a power supply for a ckt which requires 200ma of current and my transformer is 9Vac at 500mA.
and then i have used a bridge rectifier and a 2200uf capacitor and after capacitor i have used LM317 as i need 5.1V at 200mA.

But my transformer and small heatsink of lm317 as getting hot
so what is solution to reduce heat
my ckt remains on for 24hours daily.
Is this heating obivious and i should ignore it

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MSc Electronics
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Is this statement based on power dissipation calculations and measurements? Or did you just feel it with your hand?

 

I have feel it with my hand.
The transformer is becomming hot and even the the regulator ic.
it is not so hot that it will burn you but still it is unbearable.

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As I replied in your other posting, something is wrong in the wiring of your circuit, most probably the bridge rectifier. I have a similar LM317-based PSU operating continuously with very little heat anywhere.

AllVol

 

Does the power supply gets hot when running no-load.?

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"Give a man a fish, and he will eat for a day. Teach that man to fish, and he will eat for a lifetime."

 

no it does not get hot without load it only become hot with load

i am drawing 150mA in off state of switch and 200mA in on state of switch
50mA is used in making relay on.

this may be the reason
"U must be knowing that in india the transfomer rated 500mA can give 250mA and then ouput falls or in other words loading starts"

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catcat:
please donot mail bmp files as they take up more space
instead save bmp as jpg files they take less space

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What about this?

Attached Images

1psu.bmp (161.7 KB, 32 views)

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OK, Who put the LED in backwards?

 

Cat

What is that supposed to do? Identify L1, L2, please.

Nikhil-- Can you post your circuit as you have it?

Allvol

 

Attached is a workable circuit for LM 317 power supply. Does this match your circuit, Nikhil?

AllVol

 

It transforms the 120vac mains to dc voltage specified by transformer. C1 and C2 would be about .1 uf, the diodes just standard silicon or rectifier diodes, the inductors about 1000 to 10000 uH. You could add a series resistor to limit current.

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OK, Who put the LED in backwards?

 

It transforms the 120vac mains to dc voltage specified by transformer. C1 and C2 would be about .1 uf, the diodes just standard silicon or rectifier diodes, the inductors about 1000 to 10000 uH. You could add a series resistor to limit current.

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OK, Who put the LED in backwards?

 

Thanks, Catcat

That circuit threw me for a minute. I've never seen one configured like that. Since capacitors do not pass DC, how can that work? Are c1, l1, for example, a filter? I'm afraid I don't understand.

AllVol

 

Your transformer's voltage is too high for a 5.1VDC supply. No wonder the regulator gets warm.
9VAC makes a peak of 12.7V which is reduced to 11.2VDC by the bridge rectifier. Therefore the LM317 has 11.2 - 5.1= 6.1V across it and 0.2A through it which is 1.22W of heat.
The LM317 needs a min of about 3V across it for it to regulate very well.

If your transformer gets hot at less than half it max current rating then its quality is crap.

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Uncle $crooge

 

what else we can do audio guru. i want to stick to linear supply only.

my input is 220VAC.

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