Circuit advice needed, EE's... help me out here!

[WhereTheHellIsJames?]

Here's what I'm trying to do...

There is a running light on the front of my motorcycle, that is normally on constant. What I would like to do, is to get it to blink with (or opposite of) my turn signals when they're engaged. The running light power must remain constant, and the light should remain on, unless power from the turn signal circuit is applied, in which case, the light should extinguish.

In the picture below, assume that the square is what I need (two wires going in, one coming out- power to one wire and the circuit is closed, power to both wires, and the circuit is open), that the wire from the left is from the turn signal circuit, and the wire from the right is the running light circuit...

Here's a link to a YouTube video of what I'm looking to do...


There's no explanation of what was done, but my goal is similar to what the bike in the video does.

This is 12VDC, and is a relatively small bulb (like a motorcycle turn signal bulb). Dual filament is out of the question due to mounting option restraints. I'm open to any ideas, but if there is a way to do this solid state instead a mechanical apparatus, then that would be the best option. FWIW, I'm handy with a soldering iron

Thanks in advance!!

 

[elmo_4_vt]

Doesn't seem too hard... You can just take the power source of the front blinker and run it through the coil of a relay. Take the wire to the front running light on the same side and run it through the normally closed (NC) contact of the same relay. When the relay coil gets power from the blinker, it will open the contact, and turn off the running light. The only thing you'll have to watch is to make sure the power draw from the coil doesn't dim the light on the blinker too much, but it shouldn't be an issue. A solid state relay would be the best, and smallest solution. Do that for both sides and you'll be set. I'll make a quick drawing if you need.

Don

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Edit: Solid state relay from amazon (a little pricey): http://www.amazon.com/HELLA-H41773001-Solid-State-Ceramic/dp/B000VU5FPE
Standard automotive relay: http://www.amazon.com/Absolute-RLS125-12-VCD-Automotive-Relay/dp/B0002KR9GG
Or you could get fancy with smaller, less expensive solid state relays.

 

[WhereTheHellIsJames?]

Don- Thanks! That's along the lines of what I was thinking, but am looking for the smallest possible option- especially since I'll need one for each side.

Found these this morning... they're close to what I need, but instead of turning a running light into a blinker as well, the turn a blinker into a running light. Same difference though. I'd like to make the parts myself, but if I can't figure out what is under the shrink tube on those magic blinkers, then I suppose I'll just buy a set of theirs.

Edit: It looks like they're using a MOSFET as the switching device. Any insight on how to build the part/circuit that I'm after would be greatly appreciated!

 

[Mash5]

Basically a MOSFET can be thought of as like a relay in operation with the following exceptions:

• It is VERY static sensitive so care must be taken in handling them. never just pick one up.
• You will need a "drain" from you signal to ground through a zener diode to ensure it switches as a tiny bit of residual static will keep is switched.
• They are generally used in the ground side rather than the power side. (don't know why)
• I may need a heat sink depending on the amps you lights draw. My guess is no but do the math.

I'm not an EE but I have used them for a few projects. It takes a bit of research for me to figure out all the details and get it right. If you have questions ask and I'm sure I can help.
I would recommended you DL and use TinyCad. Its a free schematic tool you can use to get it all right before you start soldering. Email me the TinyCad file for what you have in mind and I'll give you my 2c. After I get the schematic right I also draw out the physical circuit by hand to eyeball scale as I find this helps me get it right the first time without using up all my desoldering braid.
Sounds like a fun project.