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Need help to build 15V dual power supply

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venu01

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I am building a power supply using transformer. In put voltage: 220V, 50Hz
Out put : + 15V 0 -15V 8Amps current. Can any one provide me schematic drawing for it?
 
There are dozens if not hundreds of schematics for power supplies available if you simply search using Google.
 
After googled I have made a circuit attached hear with. please verify and and make suggestions if any to improve the circuit. I have made the circuit to suit 15V, 5Amps which will serve my purpose.
 
hi,
The 120VA transformer will not provide a 5Amp output, closer to 3Amp.

A rough transformer VA , would be 30V * 5 = 150VA, also you should allow for the voltage drop in the regulators, say 3V.

That would require a 36V * 5 = 180VA transformer.
 
You also need to check the drop out voltage of the regulator is within limits at full load.

I have come across many transformers that quote 18v at 10 amps, but sadly not at the same time.
 
It's common practice with transformers WTP Pepper. Voltage is always measured open circuit.
 
It's common practice with transformers WTP Pepper. Voltage is always measured open circuit.

This is not what I have found, commercial transformers are quoted as the rated outed voltage at the rated current, otherwise the ratings quoted would be meaningless.
 
Please help me to build step down transformer 220 to 12-0-12 volts 1.5 x 2.5 bubbin. what number of turn to 220 volt primary and wire size to secondary 12 volts. 40 to 50 amperes.
 
Please help me to build step down transformer 220 to 12-0-12 volts 1.5 x 2.5 bubbin. what number of turn to 220 volt primary and wire size to secondary 12 volts. 40 to 50 amperes.

Better you start your own thread.

Be ready to buy a lot of copper wire.
 
hi,
The 120VA transformer will not provide a 5Amp output, closer to 3Amp.

A rough transformer VA , would be 30V * 5 = 150VA, also you should allow for the voltage drop in the regulators, say 3V.

That would require a 36V * 5 = 180VA transformer.
I believe he said he wants both + and - 15V @ 5A per side. Tht's a total of 150 Watts of load power, VA rating on the transformer would be more like 250VA or higher to power both outputs and allow a small drop over the linear regs. The RMS transformer secondary current is about 1.5X DC load current with FWB diode/cap design.
 
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After googled I have made a circuit attached hear with. please verify and and make suggestions if any to improve the circuit. I have made the circuit to suit 15V, 5Amps which will serve my purpose.
Be advised you will need massive heatsinks for this, and the design is not feasible for full current at low output voltages. At say 2V output at 5A load, you would have about 16V drop across the linear reg which would be about 80W. That exceeds the safe power dissipation for any monolithic linear reg. The one you called out specs 1.5C/W thermal junction to case, add another 0.5 for mount to the heatsink that means 80W will raise the junction temperature 160C above ambient even with an infinite heatsink. Design not feasible.

A linear design is possible, but you would need to split the power dissipation across two or three power transistors and you would need a BIG heatsink..
 
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Thanks to every one, for their prompt positive resply. I have learned/ educated a lot from you.
Thanks to all once again.
 
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