Multiple transformers, one input mains line

[Johnson777717]

Heya folks!
Some advice if I may?

I'm building a bench power supply unit which utilizes:
1. 7812 regulator for regulated 12+ output
2. 7805 and 7905 for regulated +5 and -5 output.
3. 317 and 337 for regulated variable output. (for those in between voltages).

the entire circuit is basically 3 circuits in a single box, which output to their own exclusive jacks and are metered by a display. Selection of which output is based upon a rotary switch etc.

Finally, only one power supply circuit may be used at one time, so the circuits will not output in conjunction.

The circuit diagram that I have uses a single primary, triple secondary transformer. Primary is 60 Hz 120 VAC. The secondary values stated by the schematic are:
1. 25 VAC (For the 317 / 337 circuit)
2. 17 VAC (For the 7812 circuit.)
3. 8 VAC (for the 7805 / 7905 circuit)

I dont really want to invest in a triple secondary transformer, because I have a single secondary transformers that will fit the bill.

My questions:
1. Will it work if I have a single input mains line (120 VAC 60 Hz) going to three single secondary transformers? (remember, only one circuit will be used at one time.) Are there any drawbacks to this type of setup?

I thank you for your time, and any assistance that you may provide. Thank you very much!

 

[ljcox]

The circuit you posted will work, but I would use one transformer with a single, centre tapped secondary.
It won't be as energy efficient, but will require less space.

Len