# Circuit diagram needed!

Discussion in 'The Projects Forum' started by plharby, Dec 3, 2008.

1. ### plharby Thread Starter New Member

Dec 3, 2008
2
0
I am working on a project to make a useful charging controller (regulator) for a Chinese produced motorcycle equipped with a single phase alternator. The owner has not been successful in getting a replacement for the defective one originally mounted in the bike. The alternator (AC) only has a permanent magnet rotor and fixed stator coils which makes it a brushless type. Between the two output wires may as much as 160 V p-p occur.
Problem: This has to be rectified and the voltage reduced to ca 14V to charge the battery. This has to be done without too much heat being produced. Charging current average around 4 amps, but may be less when battery is fully charged and load is light.
Can anybody give me solutions to this problem? Circuit diagrams?

Harby

2. ### Bernard Expert

Aug 7, 2008
5,226
600
A wild thought: Start with an inexpensive switching power supply such as Fujitsu 100-240V /50/60 Hz, output 16V @ 3.75 A, about \$14.95,add an outboard regulator for battery charging. This PS was listed in an old ALL ELECTRONICS Cat.

3. ### DickCappels Moderator

Aug 21, 2008
5,746
1,800
Just curious - is the 160V P-P unloaded? Any idea of what the voltage was when it was connected to a working charging system?

4. ### princea New Member

Dec 30, 2008
1
0
This site is indeed helpful, thanks alot.
But i need schematics on how to build ac voltage regulator and stepup transformer.

thanks onece again.

5. ### Alberto Active Member

Nov 7, 2008
169
36
Harby, I don't think you will solve your problem with a switching power supply because the frequency out of you ac generator will be higher than 50/60 Hz.
Frequency output will depend from motor revolution and I suppose to be very high indeed. (if you can measure it, I will be curious to know the value)

One way to explore could be: convert ac to dc with a proper bridge rectifier than use power mosfet and pwm technique to control dc output.

Alberto