Powerdynamo, taillight protection wire on 18W systems

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Powerdynamo, taillight protection wire on 18W systems

wiring suggestion for 788 systems (6v/18w without regulator) to prevent trail light blowing when changing between low and high beam

If headlight and taillight bulbs are wired normally in parallel, it happens that during switchover from low to high beam or reverse, there is briefly no current on the headlight bulb and as a result voltage may rise at the taillight bulb, blowing it. This is not only so on our systems 788, but also on stock systems. Some manufacturers at the time combatted this with either including a trottle coil or by using safety wiring of the tail bulb.

we here describe this safety wiring and recommend that you use this with our 788 systems if the bike has a dipswitch and is therefore liable to taillight blows

What you need to do (it might be that your bike has already such wiring, so check) is to disconnect the grounding of the taillight lamp and install some additional wire to the bulb, replacing the former ground connection. You now have 2 wires from the taillight bulb.

Connect them, one each, to the high and low beam contacts of the headlight bulb as shown above (and also shown in basic wiring diagram below).
With this wiring when the dipswitch is between the states and does not supply the headlight bulb (which would be the moment of risk for the taillight bulb) there is also no voltage at the taillight bulb. Note hoiwever that if the headlight bulb blows, your taillight will not shine any more either.

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