Need help for power supply

[nkn]

I have transformator whit two secondary 10v/5A ,i need to have +12/3A - /+C2/ and + 23/1.5A - /+C1/

 

[crutschow]

You put the two secondaries in series (observe winding polarity). Connect a full-wave bridge rectifier to the outputs of the two windings and ground the negative output of the bridge rectifier. Add filter capacitors from the bridge output to ground and from the transformer center-tap (connection between the two windings) to ground. This will give approximately 26.5Vdc from the bridge output and 13Vdc output from the center-tap. You can use linear regulators to get the 12V and 23V you want.

I know it may seem strange to get DC out of the transformer center-tap, but if you look at the circuit you will see that the two diodes to ground in the bridge are acting as full-wave rectifier diodes for that output. Note that, in this circuit, the bridge rectifier must be capable of carrying the sum of the two currents or 4.5A.

Note that if you pull that much DC current from that transformer it will be overloaded, since you must derate transformers when they are driving rectifier capacitor loads. This is due to he high peak current (and thus high Irms power) required by such a load from the transformer.

 

[nkn]

thanks.it is two circuits who is more praktic.

 

[nkn]

sory i have problem to brouse then circuit.it is possible to print you idea.thanks.

 

[crutschow]

Below is a simulation of the circuit. The capacitor values are arbitrary. You may need larger values for the amount of current you want to draw.

 

[nkn]

thanks.