Simple Voltage Regulator Circuit Sought

[Rick]

I am a Newbie to news groups so I apologise in advance for any
transgressions in Nettiquette!
I have recently completed rebuilding a 45 years old small motorcycle,
as a project, and would like to improve the lighting/charging system.
The electrical system is 6volt with a flywheel/magneto containing an
ignition coil and a lighting/charging coil. The brake light,
indicators, horn and neutral indicator lamps are powered directly from
the battery, the headlight, taillight and instrument light are powered
from the lighting coil. When the lights are switched 'on' the
lighting circuit is paralleled to the charging circuit (a rectifying
diode feeding the battery). The lighting coil has one end earthed to
the frame. This means that the lights only work when the engine is
running. With the lights switched 'off' a tap from the lighting coil
is switched to the diode to provide a reduced 'trickle' charge.
I would like to feed everything from the battery and use the lighting
coil exclusively for battery charging. This would mean using a
voltage regulator to avoid overcharging the battery. I envisage a
circuit thus: coil, via rectifying diode and current limiting resistor
then another diode, to battery positive. A Zener diode between the
resistor and the second diode is connected to earth (frame) to control
maximum voltage.
My problems are:
1. is this adequate, and (if so)...
2. please, what values for the various components?
A refinement would be some sort of indicator (e.g. LED) that glows
when more current is flowing out of the battery than is being
replaced, operating like the ignition warning light on a car. Is it
possible to connect such an indicator, to which part(s) of the circuit
and what components (besides the LED) would be required?
I, and many other small bike enthusiasts, would be very grateful for
any help on this matter. Please write to me at <[email protected]>
and thank you for your time and consideration.

 

[Robert Baer]

I am a Newbie to news groups so I apologise in advance for any
transgressions in Nettiquette!
I have recently completed rebuilding a 45 years old small motorcycle,
as a project, and would like to improve the lighting/charging system.
The electrical system is 6volt with a flywheel/magneto containing an
ignition coil and a lighting/charging coil. The brake light,
indicators, horn and neutral indicator lamps are powered directly from
the battery, the headlight, taillight and instrument light are powered
from the lighting coil. When the lights are switched 'on' the
lighting circuit is paralleled to the charging circuit (a rectifying
diode feeding the battery). The lighting coil has one end earthed to
the frame. This means that the lights only work when the engine is
running. With the lights switched 'off' a tap from the lighting coil
is switched to the diode to provide a reduced 'trickle' charge.
I would like to feed everything from the battery and use the lighting
coil exclusively for battery charging. This would mean using a
voltage regulator to avoid overcharging the battery. I envisage a
circuit thus: coil, via rectifying diode and current limiting resistor
then another diode, to battery positive. A Zener diode between the
resistor and the second diode is connected to earth (frame) to control
maximum voltage.
My problems are:
1. is this adequate, and (if so)...
2. please, what values for the various components?
A refinement would be some sort of indicator (e.g. LED) that glows
when more current is flowing out of the battery than is being
replaced, operating like the ignition warning light on a car. Is it
possible to connect such an indicator, to which part(s) of the circuit
and what components (besides the LED) would be required?
I, and many other small bike enthusiasts, would be very grateful for
any help on this matter. Please write to me at <[email protected]>
and thank you for your time and consideration.

Use one of those regulators from a car - even if it is of the older
"vibrating relay" type.

 

[[email protected]]

Use one of those regulators from a car - even if it is of the older
"vibrating relay" type.

That would be my recommendation as well, although it might be easier
to find a 6-volt regulator in a tractor application.

All the motorcycle regs I've dealt with simply ground the coil leads
causing them to not produce any power. This is done before the diodes
so you don't short the battery. You don't want to simply disconnect
the coils because they will generate high voltage which can cause
breakdowns and arcing.

You might also be able to modify an older motorcycle mechanical type
regulator. Basically, those look just like a relay that clicks exactly
when the voltage is correct. Usually, you see people trying to swap
these out for newer electronic versions for better reliability and
voltage control. If at all possible, I'd try to find an electronic
module. On a bike that old, I image the biggest problem is getting
things reliable (well, after dealing with all the dried up gaskets).

Just curious, what make/model of motorcycle?


-Chris