alternator circuit

[pgw1@yahoo.com]

I have an old BMW motorbike retrofitted with an a 12V alternator, I
would to find a circuit for an 'idiot light', so that when the ignition
is turned on the lite is lit, when the engine is started the light goes
out if the alternator is working, but stays on if the alternator is
malfunctioning. It of course would go on if the alternator
malfunctions when the bike is running. if someone can direct me to the
circuit or send me a schematic, I would really appreciate it. Please
send directly to my e-mail address if possible. Thanks.

 

[John Popelish]

"pgw1@yahoo.com" wrote:

I have an old BMW motorbike retrofitted with an a 12V alternator, I
would to find a circuit for an 'idiot light', so that when the ignition
is turned on the lite is lit, when the engine is started the light goes
out if the alternator is working, but stays on if the alternator is
malfunctioning. It of course would go on if the alternator
malfunctions when the bike is running. if someone can direct me to the
circuit or send me a schematic, I would really appreciate it. Please
send directly to my e-mail address if possible. Thanks.

This is ordinarily done by connecting a lamp between the three diode
half bridge that feeds energy to the regulator (that regulates current
to the rotor) and the ignition key switched line to the main rectifier
output to battery positive. If the alternator is charging the
battery, there is essentially no voltage across the lamp. If the
alternator is not producing enough AC to send any current out the main
rectifier (and, so the three diode half bridge is also not delivering
much current ot the regulator, the lamp lights and also provides a
minimum current to the regulator. Turning the ignition key off
disconnects the lamp form the battery when all the other loads are
turned off.

--
John Popelish