Newsgroups: sci.electronics.misc
Subject: Re: converting 6v ac to 12 v dc
References: <[email protected]>
From: Tomi Holger Engdahl 
Date: 31 Jan 2000 00:29:48 +0200
Message-ID: 
Organization: Helsinki University of Technology, Finland
Lines: 57
X-Newsreader: Gnus v5.6.45/Emacs 19.34
dan d man  writes:

> i have a small generator (6v 3w) off a bike.  how do i
> convert it to 12v dc

Try the following circuit (drawn using fixed fonts, the only
way to draw ASCII pictures which can be properly viewed with
all screeen, if down not who right, use Courier or similar font):


           +---|>|-+---------- 12V out positive
           |       |
           |      ===
           |       |
 6VAC -----+       +-- 6VAC
           |       |
           |      ===
           |       |
           +--|<|--+---------- 12V out negative


Calculate the diode rating to be able to handle double the
output current needed (1N4001 will work up to 500 mA loads nicely).

The filter capacitors should be calculated like normal
filter capacitors for certain rippel and output current
and operating frequency C = Ioutput / (Uripple * frequency).
The only difference here is that those both
capacitors should be 2-3 times bigger than that
normal equation gives. I would start from something
like 4700 uF.


-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/