Automotive - using turn signals as combo turn signals and running lights

THE GOAL:
I have a vehicle equiped with turn signals, but no running lights. I would
like to be able to use the turn signals as combination turn signals/running
lights. For a variety of reason, I cannot replace the pigtails or the
sockets to accommodate dual-filament bulbs. Instead, I've come up with the
following solution:

THE SOLUTION:
Use a relay (one per side) and connect the turn signals to the normally
closed circuit (power to the turn signals coming from the tail light).
Activate the relay by use of the turn signal lever on the steering column.
The automotive flasher unit then turns the turn signals off by switching the
relay to the normally open circuit (to which I have nothing connected).

THE PROBLEM:
Standard automotive flashers (the thermal type) require some load in order
for them to operate (flash properly). My design above does not place a load
on the flasher, and thus my turn signals don't flash. One option would be to
place an artificial load on flasher by using a low resistance, high wattage
resistor. This works, but generates a tremendous amount of heat (which I
really want to avoid). I've looked into creating my own flasher using a 555
chip. But since I'm very new to electronics, I'm not sure if this would
solve my problem, either.

Any help is appreciated!

Regards,

Greg Bender

 

This looks like something I've always wanted to try. Use one 555 (or half
of a 556) to run a chopper at about 100 Hz or so, with a duty cycle enough
less than 99% to dim the lights visibly - to make this work, you might
have to use a brighter bulb type.

Anyway, use that 100Hz pulse to chop the 12V to both of the lights, like
with a MJ2955 PNP power transistor.

Then, use another 555 (or other half of the 556) to make your flash rate,
and simply drive another MJ2955 to turn the one light to full-on for the
duration of the flash. You'd use a couple of diodes to make an "OR"
function.

I'm way too lazy to draw a schematic, but it's such a simple circuit in
concept, that there will probalby be at least two or three up in a matter
of hours. ;-)

Good Luck!
Rich

 

Thanks Rich! Hopefully someone will post a schematic.

 

Hey Greg
Rich's idea was to dim the lights but if you want to do it easier you
can skip the chopper/dimming half of the circuit. Just turn them on
and off. The manufacturers' datasheets for the 555 on the internet
have example circuits. The 555 by itself won't deliver enough current
for the turn signals, so you will have to drive a relay or power
resistor from the 555.
Or if you want to make it really simple you can go back to the resistor
idea and I would suggest instead of using a resistor use a 12 volt bulb
that draws enough current to make the flasher work. Bulbs make great
power resistors. Stash it under the dash or hood where it won't bother
you.
There is one disadvantage to the whole thing. With your car's original
wiring you have the safety factor of knowing when one of your turn
signal bulbs burns out, because the flasher rate will slow down or stop
flashing altogether. If you change your circuit so that you use a 555
or a flasher with an independent load, you will have no feedback from
the turn signal lights, so you won't know if one of them burns out.
Makes it more likely that you will get stopped by the police, and they
will find the recreational substances.