Help needed to design aux lighting circuit

[TestPilot]

Here's my challenge:

Zea's 600Fazer illuminates the left headlight only on low beam (H7 bulb). The right headlight in an H4 bulb (same as FJR - managed ot get FJR mentioned ) but the low beam is not used at all. On high beam the left headlight stays on, and the high beam on the RHS H4 lights up.

This is all as designed, BUT I want more! Foe added visibility I want both headlights illuminated on low beam (easy to do - run a jumper lead and put a relay in the circuit so as to not overload the wiring), BUT then on high beam both filaments of the H4 buld will be lit, and the heat may be too much for the headlight assembly/reflector.

Here's my thought: I need a circuit designed that will activate the H4 low beam (from the other headlight is fine) on low beam, BUT when she switches to high beam the new circuit must be de-activated, so only the high beam in the H4 is powered.

Anyone out there able to design a circuit that a novice can build and instal?

 

[Warchild]

Anyone out there able to design a circuit that a novice can build and instal?

Yep.... I had a somewhat similar issue, though it's not exactly like your problem, you can use the same general technique...

In any event, here's how I went about solving it: https://www.fjrtech.com/getdbitem.cfm?item=49

 

[bramfrank]

I read through the question and don;t quite understand what he wants to do, so I've sdtayed out of it . . .

However a 3 amp diode isn't going to cut it for a 60 watt bulb (high beam on an H4 is 60 watts - you need at least 5 amps - and because you've jumped the high and low beam wiring at the socket you'll need 10 amps at least. A single wire to what you call the HID relay is all you need - take the signal from any of the 'common' high beam points . . . .

Again, assuming I understand the requirement; this variant that doesn't put all of the bulb current through the diode is as follows (you still need a larger diode):

 

[TestPilot]

Thanks for the great and helpful suggestions. Reading through the posts I realise I did the usual when I don't know enough - I described an overly comlpex way of achieving what is a relatively simple solution. The simple 'request' would have been:

I want power to the H4 lo-beam circuit whenever the H4 hi-beam circuit is NOT energised.

Someone elsewhere suggested using a 'change over' relay (Narva part no 68044BL), and this is what I do:

Pin 30 Power In (will be a lead straight from power source so as not to overload any existing circuit, but triggered by a relay connected to the existing H7 lo-beam. In other words, the circuit is only energised when H7 lo-beam is on, which is all the time the headlights are on)

Pin 85 Earth

Pin 86 SWITCH (the key) Connect the existing H4 hi beam as the switch

Pin 87 Power Out Normally Open - this goes to the (existing) H4 hi-beam. So, when lo-beam is selected, circuit 87 is NOT energised; when hi-beam is selected the switch (pin 86) closes and circuit 87 is NOW energised.

Pin 87a Power Out Normally Closed - this goes to the H4 lo-beam - my new lo-beam. So when hi-beam is NOT selected, circuit 87a is closed (energised); and when hi-beam is selected circuit 87 is energised, and 87a is de-energised.

Whoo hoo - part bought (about $16) & will install over the weekend.

 

[bramfrank]

Sounds like you have it right - don't forget to fuse the feed from the battery.