Thread: OT- Help on simple full-wave rectifier circuit

1. OT- Help on simple full-wave rectifier circuit

I'm out of touch with electronics circuitry for 30+ years. Your help is appreciated.
The charger for my power drill battery went kaput due to an open primary at the power transfomer.
The ouput of the charger is at 18v DC 500mA non regulated. The rectfier is a simple full wave non-center tap.
I intend to replace the transformer but cannot remember the formula to calculate the secondary ac output voltage.
Can some electronics gurus help pls?
TIA

2. Re: OT- Help on simple full-wave rectifier circuit

tin the ratio of the incoming AC voltage to stepdown AC voltage. 230V/18 which is approximately 12:1. so that is the transformer u'll need.

3. Re: OT- Help on simple full-wave rectifier circuit

Originally Posted by user12343
tin the ratio of the incoming AC voltage to stepdown AC voltage. 230V/18 which is approximately 12:1. so that is the transformer u'll need.

Thanks a lot

4. Re: OT- Help on simple full-wave rectifier circuit

Hmm, assuming you are referring to 18VDC @ 500mA (after rectification via a full wave rectifier), the pre-rectification AC voltage will be 18V/1.414 = 12.72V. If you use a transformer with a 18V AC secondary, you'll end up with 18 x 1.414 = 25.452V which is probably too high.

Regards
CK

5. Re: OT- Help on simple full-wave rectifier circuit

Originally Posted by ckiang
Hmm, assuming you are referring to 18VDC @ 500mA (after rectification via a full wave rectifier), the pre-rectification AC voltage will be 18V/1.414 = 12.72V. If you use a transformer with a 18V AC secondary, you'll end up with 18 x 1.414 = 25.452V which is probably too high.

Regards
CK