Dear experts, I have some old lights I want to use for parking lights, running lights and turn signals. Do I need bulbs with two contacts? Thanks
You can do it with single element lamps, but you have to get creative with relays. Far simpler to use dual element lamps. And I wouldn't do this with taillights.
There are some 2 element pigtails that can be put in a single element socket and run a 2 element bulb with straight across pins. I had those in the park lights on the 48 in the early 70's but they were a real pain in the butt to get everything right. I don't remember The bulb number but a bit of a search should find it. If it were me I'd figure out how to change the sockets in the lights to ones that work with a 1157 style bulb and live with a lot less headaches.
Lots of car show vendors will sell 1157 sockets and pigtails. Ron Francis sells an extra bright 1157 bulb you might want to consider. You don't mention it, but the 1157's and what everyone is talking about are for 12 volt systems.
Pretty simple to use a single 1156 backup light bulb for park/turn signal. Either a simple PWM circuit or a simple resistor that is activated by parking light switch can be used to power the bulb at a lower brightness. Then use a diode isolation block and wire this to isolate the turn signal from the PWM or resistor circuit. A couple of dollars in parts.
What is the difference between parking lights and running lights that would require a separate filament (except that you are using one while running and one while parked)? If you are using the turn signals you want to shut off the other lights which means one filament would be fine. I am not sure what you are trying to accomplish. I think I am missing something unless you are saying you want a brighter filament for the turn signals. Charlie Stephens
In either case, the LED's are so low voltage you'll still need some help in the wiring with resistors to increase the draw. But, my primary objection is that LED's look like LEDs and they don't belong on traditional hot rods. If you want a brighter light,use a brighter lamp.(http://www.ronfrancis.com/products.asp?dept=94)