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Power supply

Hi all,

I have been reading on power supply because my transformer died. I have been reading up on making my own power supply, Although I have a transformer that I initially started using, Then I discovered that this transformer (primary: 115v 60hz 33VA, sec 33v 1.0 A) heated quite a bit after just a few seconds, but still gave me the right voltage either way. I put two different bridge recifier after that (one at the time, rated up to 1000v and 3 and 4 amps, so enough) these bridges completely burnt. I used another transformer with 12v output, and no heating at all. Would that transformer at 33v output be out of order ? My voltmeter says it works, but seems to have much much more amps then they say.

k
Reply to
Ken O
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To check for a fault in the transformer, just connect the primary side to he line (through a fuse), and see how long it takes to get hot, while you check its output voltage.

If rectifiers are burning up, it almost certainly is not the fault of the transformer, but of the load being larger than you think. What are you powering with this supply?

Reply to
John Popelish

Actually nothing, I was just testing if it worked, Wall outlet to the primary side transformer, secondary to the bridge and a big capacitor (110v

3300uF). If I use another transformer the brifge do es not heet up . It takes about 3-4 seconds before smoke was coming out the bridge, and transfomer was hot too, but not burning hot. The second transformer I sued was not rates 33v on the secondary as the first one, but 24.5v.

Ken

Reply to
Ken O

What does the 33 volt transformer do if the bridge rectifier is not connected to it?

I guess it is possible that either the rectifier or the capacitor is having a very specific break down that occurs below the peak voltage from the 33 volt transformer (about 47 volts) but below the peak voltage from the 24 volt transformer (about 35 volts). Once smoke comes out of a rectifier, it is certainly damaged goods.

Reply to
John Popelish

Well I'll through those rectifiers out then. I am using the other transformer now with no problem, The bridge is not hot at all, but the transformer is a bit hot, I can touch it but a few more degrees it would be hard. Is that normal ?

K
Reply to
Ken O

meg your transformer. i bet you mite have the common (-) tied to the chassis which the transformer is also attached too ? you transformer maybe leaking. disconnect the (-) output from the chassis and place an amp meter between the (-) and chassis.. you should be getting very little reading.

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Reply to
Jamie

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