converting 12 volts to 4 volts

Hi
I have a classic motorcycle and I have updated the old alternator to
a
Permanent Magnet Alternator,
but the motorcycle has a starter safety relay ( which basically stops
the starter motor from reengaging once the engine has started)
which is activated by 4 volts from the old style alternator
now i need something small rugged and vibration proof to step down
the voltage from 12 volt to 4 volt
any ideas
Jamie

 

It's actually an LM317.

http://www.national.com/mpf/LM/LM317.html
http://www.google.com/url?sa=t&ct=r...q94IoCmnUPkZ9qd8A&sig2=zDfKQFQ8myiJCG_vU-psCQ

Sample circuit is in that lot.


G-S

 

An LM317 will handle up to about 1.5A of current. If the relay needs
more than that (which seems unlikely) then an LM350 will probably do
the job.

http://www.electronics-lab.com/downloads/datasheets/general_regulators.html


BTH

 

I would think a simple resistive divider would do the job ? and how much
voltage and current will the relay handle , can the relay be upgraded ?

 

Figure out the current draw and use a resistor in series. Simple and
cheap.

Theo