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Converting Ac to Dc current.

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benchmark:
Pardon me as my Physics is not at sharp as it used to be.
Probem is tat i ae a small stepper motor i want to use as a generatr run on one f my model steam engines.
The motor as 4 wires leading out of it , 2 pairs each that generate up to 75 vots Ac current each when i test run it.

Now, apart from me aking a diode bridge rectifier to achieve this, do you guys know any place or link to any small ready made cuircut that can serve?

Secodly what would be the best configuration of connecting the 4 wires be to get maximum perfomance.

BillTodd:
Just use two small bridge rectifiers like this: (it's a very common component so you should be able to find one locally)

http://www.rapidonline.com/Electronic-Components/Discrete-Semiconductors/Bridge-Rectifier-Diodes/1.5A-Bridge-rectifiers/29687/kw/bridge+rectifier



connect both AC inputs (marked ~) of one rectifier to the wires of one coil and AC inputs of the other rectifier to the other coil. Then connect the two positives (+) together and the negatives (-) together as the outputs.

The output voltage could potentially be quite high when unloaded (75vac will generate 75 * 1.414 = 106vdc)  ,  so be careful what you connect it to.

Bill

John Swift:
Hi Benchmark ,

with the bipolar motor you can connect a bridge rectifier to each winding

then either parallel the DC outputs to give the maximum current out


or if you smooth the DC with a capacitor across each bridge rectifier
wire the two in series to give a higher voltage

if you had a unipolar motor you could have used just two diodes per phase


 John

benchmark:
Chhers guys, i like those small bridge rectifiers, i guess the 1.5A 200V ones will do?

However , following the connection arrangement you suggest 106 Volts DC is  just too much as i will only be lighting up small bulds and LEDS , any other suggestion for a connection that gives about 50 volts?

picclock:
Hi Benchmark

If you connect the windings in series, getting the phase right to give you 150 volts you can connect that to a redundant mobile phone charger (hide it in the base). They will normally run from 100 - 240v AC and they are not fussy about frequency. The output of these is normally 4-5 volts, just right for running some LED's (via a resister  :zap:) and small bulb's from. If you remove the charger case the electronics are quite small. the largest thing about them is the mains connector, just remove that and solder your generator wires to the connections.

Good luck and show us the pictures.

picclock

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