6 V Dynamo Regulator

This ’bulletproof’ electronic regulator was originally designed to replace the troublesome original electromechanical regulator on the author’s vintage BMW/EMW R35 motorbike. A large number of BMW/EMW devotees have since successfully tested this unit on their machines without problem. The design is universal and should be suitable for all bikes using the same switched-earth field regulation method.
The author designed this regulator for his EMW R35-3 motorbike. The bike was built by Eisenacher Motoren Werken (EMW) based upon the prewar R35 machine from BMW. Production of the bike continued for many years after 1945.

Resistors:

(SMD case 1206)

R1 = 6k8 (see text)

R2,R5 = 4k7

R3 = 100Ω

R4 = 1M5

R6 = S05K20 (varistor)

Capacitors:

(SMD case 1206)

C1 = 4nF7

C2 = 3µF3 (ceramic multilayer)

Semiconductors:

D1 = LL4148

D2,D3 = zener diode 5V1 (SMD)

D4 = zener diode 9V1 (SMD)

D5 = EGP50D

D6 = BYV32E-100

T1 = BTS115A

IC1 = MAX291

PCB, ref. 050241-1 from The PCB Shop