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Electronics Repair Forum
Forum topic/blog entry started by Scott on 4/16/10 2:36:37 PM (server time).
This topic has been viewed 5580 times.


Making my own rectifier/regulator for motorcycle & cars


I was interested in electronics when I was younger but have forgotten most of what I learned. I sometimes restore motorcycles and a common fault is damages rectifiers and regulators. I'll be buying another old wreck to restore soon, and will want to refresh the electronics. I don't want to rely on a 30 year old rectifier because I am often out on the highway a long way from anywhere.

It is simple circuitry, and I once made a rectifier out of second hand television parts to replace a damaged one in a motorcycle, but can't remember how I designed the circuit. Could someone describe the circuit layout for me so I can make a few rectifiers so I can easily replace them in vehicles. They work just as well in cars as in motorcycles so a few of them made ready to install would be great. I would like to include the rectifier and 12v regulator together, but making them seperate circuits and just wiring them together would probably be the best way to do things. I'd like the simplest design possible, i.e. I think it was just 4 capacitors layed out a certain way. What type/size capacitors should I use for longevity and reliability. I'll use old TV components again.

I seem to remember that I'd make the regulator to output slightly higher than 12v (something like 13.4v) so that it charges the battery properly. Is there a IC available now that will do that. I'd say there probably is. If you can advise me of the part number for that, I'd use that to regulate the voltage and then just make my own rectifiers, which would be the easiest route I think.

Can anyone help?

Thanks in advance.
Reply from/

5/31/11 12:01:26 PM

Actually i was interested in the same thing. see the Old bikes eat up RR's (regulator rectifier's) alot...I think its horrible alternator designs... but here's why they blow out...when you rev up the engine..the engine puts out 280+volts into the voltage regulator and some rectifiers can't handle that voltage for a long period of time..they heat up...and if even one diode on the rectifier blows out you'll be stuck with a half wave and little or no charge capability at normal driving range. hence the RR is gone...I restore old bikes too. buying the Bridge rectifiers for high current is fairly easy you can by both 1 phase and 3 phase bridge rectifiers. they have to be put on a heat-sink. The next thing would be a linear voltage regulator...for more current you can Google "high current linear voltage regulator" and it should show you how to Parallel them quite efficiently but that does not help with the input voltage. see it can vary from 14-280 plus volts and that pretty much makes allot of linear voltage regulator's useless. what i don't know is the constant sustained current usage of a motorcycle's electrical system. Then you have the current usage when it is rev'd up, which is a guarantee. so basically i need help here just like you do. I need a linear voltage regulator...(i can have two+ in parallel with load balancing Resistor's and caps.) WITH a low drop out, High input voltage up to 400v and a stable out put voltage of 13 to 14 volts...this means it has to be something like a LM7813 linear voltage regulator but the capability of handling such high input voltage and current and out put at least twice the minimum sustained load current from the bike's electrical system.

I hope you understood all that. If you remember how to make a good one then email me the info too. at I really wanna make one too.

2/23/13 2:13:29 AM
Plz make me one I will pay

2/23/13 2:19:56 AM
Dick smith has very low cost kits. If you can't get to them then try jaycar. You csn search their site for what u need.
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