Full Wave Shunt Regulator Circuit for Motorcycle

Shunt regulator is a device which is used for regulating voltage to some fixed levels by means of shunting. Normally the process of shunting is done by grounding the excess voltage, just as zener diodes do in electronic circuits.

However one bad aspect with such regulators is the generation of unnecessary heat. The reason for heat generation is the principle of its operation where the excess voltage is short circuited to ground.

The above practice may be implemented by simpler and cheaper means, but cannot be considered efficient and advanced. The system is based on destroying or killing energy instead of eliminating or inhibiting it.

The circuit of a motorcycle shunt regulator discussed in this article takes a completely different approach and restricts the in-flow of excess voltage instead of "killing" energy and thus stops the generation of unnecessary heat.

The circuit functioning may be understood as under:

When the mobike is started, voltage enters across the P-channel mosfet source/drain pins due to the gate trigger that becomes available via R1.

The moment the high voltage reaches R3, which happens to be the sensing input of the opamp, pin#3 of the IC senses an increased voltage.

As per the set reference at puin#2, the instantaneously reacts to the situation and the result puts the output of the IC to a high logic level.

The immediate high logic pulse restricts the negative base trigger of the mosfet, switching it OFF at that particular instant.

The moment T1 switches OFF, voltage at the junction of R3/R4 reverts to the original condition, that is the voltage here now drops below the reference level......this instantly activates the opamp output with a low logic signal which in turn switches ON T1 back into action.

The process repeats at a very rapid speed, keeping the output voltage marked with +/- at a constant level determined by the setting of R2/Z1 and R3/R4.

The above principle utilizes voltage inhibition technique of the excess voltage instead of shunting it to ground, thus saves precious power and also helps to control global warming in some way.

Parts List

R1, BR2 = 10Amp bridge rectifier

R1 = 1K
D1 = 1N4007
C1 = 100uF/25V
IC1 = IC741
T1 = mosfet J162

R2/Z1, R3/R4 =