AC powwer supply

[adriel14]

How can AC voltage be doubled or tripled if my transformer has 120v/220v output? Thanks

 

[panic mode]

if you have 120V available you can use transformer as a isolation transformer to get 220V out (about double or whatever the ratio is).

if you swap primary and secondary you can get half the voltage but max power is limited to only 50% due current ratings of the windings.

if you connect one of output terminals (secondary) with one of input terminals (primary) you will not have isolation but you can get triple voltage using autotransformer configuration. in this case you need to pay attention to dot marking. if you get it wrong, instead of sum, you get the difference of voltages so output will be practically unchanged (220-120=100). if you got difference instead of sum, swap wires of one of transformer coils (either primary or secondary).

if your source is 220V, you must use 220 side of the transformer as primary. in that case you can only get output of 120V out.
if you use autotransformer configuration, you can still get sum 220+120=340V or difference 220-120=100V but again, no isolation.

 

[unclejed613]

say what????? third example will give the same POWER minus losses as goes into the primary. the current on the second side is nearly twice that of the primary side, but half the voltage.

 

[4pyros]

Look here;
https://en.wikipedia.org/wiki/Voltage_doubler

 

[unclejed613]

that's a DC supply with voltage multiplication... i don't think that's what the OP was looking for. it appeared (although the OP's english skills were somewhat limited) that he was looking for taking 120V AC and converting it to higher voltages (also AC). only the OP knows for sure.

 

[4pyros]

How can AC voltage be doubled or tripled if my transformer has 120v/220v output? Thanks

Please see the other thread. Multible posts.

 

[panic mode]

say what????? third example will give the same POWER minus losses as goes into the primary. the current on the second side is nearly twice that of the primary side, but half the voltage.

i hear you but we are thinking about different things.

what I meant was rated power of the transformer, not efficiency.
one cannot exceed any rating of the transformer unless we want it to smoke ...
in this case limiting factor would be current rating of the low voltage coil.