# Electrical circuits question (Building a special switch)

855 Views 8 Replies 4 Participants Last post by  Lavid2002
Hello Everyone.

I have a modification I would like to make to my motorcycle. Without over explaining things I have 2 lights. One light is a special light that I am rigging up to be more visible at all times on both sides of the bike (a strip LED). I got the idea to also use this "Strip" to work along side with my turn signal as well. so let's get down to it....

We'll call the LED strip light (1)
We'll call the turn signal simply light (2)
It is important to remember that the turn signal oscillates between on/off.

(1) needs to be on all the time, unless light (2) is on. When light (2) is on I need light (1) to follow it and it's on/off sequence.

Here's the other difficult parameter. I can't modify the switches on the bike. I am not going to change the turn signal switch so I only want to modify the circuit by means of cutting and altering the wires that lead 12vDC right to the lights. I have to build a circuit for an electronics course I am in this semester, so I figured this would be for fun and also for a fun circuit to build, and it will make my bike safer to ride.

I can easily set up (1) to run all the time. The tough part is setting up some device that cuts the power from (1) and makes it blink on and off with (2) until I push the button in and cancel the turn signal then I want (1) to go back on all the time.

I am great with the basics, resistors, transistors, capacitors, wiring, soldering , inductors etc... I haven't learned anything about using a voltage current to turn off a switch so far though. Any advice on what kind of electrical component I can use to make this work? A series of diodes? I am going to go draw for a while and see if I can figure something out. I have heard of logic gated before...and I KNOW I can set up logic gates to get this to work, but they work with very very small signal currents right? Not with things like this :laughing:

Thanks everyone!

-Dave
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I can't modify the switches on the bike.
So don't.

Tap power at the battery, run it through a fuse...
feed that to whatever switches you like and then on to the light.
Ground to the frame.

You can buy switches and timers and relays and wire and anything else you might like or need at a 1000 places. Twenty of them right in your town.
Have fun
1
So don't.

Tap power at the battery, run it through a fuse...
feed that to whatever switches you like and then on to the light.
Ground to the frame.

You can buy switches and timers and relays and wire and anything else you might like or need at a 1000 places. Twenty of them right in your town.
Have fun
But I am not going to hit two switches every time I need to turn on the bike.
It's dangerously distracting, and not very innovative.
Unless I am oversimplifying this....can't you incorporate a regular turn signal flasher for the "blink" and a relay to tie in the two lights? This seems more like an electro-mechanical issue rather than electronic.
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Well the bike already has working blinkers on it. So the oscillation of the blink isn't problematic, we can get that voltage from those wires. The issue is, how do I cut the constant 12v to (1) to allow the light to "blink" when it's being fed from the power to light (2)

Here's what I need short sweet and to the point

(1) constant power

I need a circuit that will electronically be able to switch between always being on, and blinking only when the turn signals are on.
Again, a relay will make that work. The NC contacts will only open when the turn signal flasher is energized...that is if you wire it correctly The relay will merely complete the circuit until the turn signal circuit is energized.:whistling2:
Again, a relay will make that work. The NC contacts will only open when the turn signal flasher is energized...that is if you wire it correctly The relay will merely complete the circuit until the turn signal circuit is energized.:whistling2:

OK, thanks

So I see how the relay can use a small signal switch to complete a circuit so it switches power supplies... but how do I get it to quit taking power from the 12vDC?

Here's what I envision happening?

Light on all the time, turn the turn signal on and the relay oscillates between PS (1) and PS(2)... this yields a light that is always on, that cycles between two 12vDC power supplies at the same time interval that the blinker flashes at. No?

-Dave
So I see how the relay can use a small signal switch to complete a circuit so it switches power supplies... but how do I get it to quit taking power from the 12vDC?

Here's what I envision happening?

Light on all the time, turn the turn signal on and the relay oscillates between PS (1) and PS(2)... this yields a light that is always on, that cycles between two 12vDC power supplies at the same time interval that the blinker flashes at. No?
Maybe I'm confused about what you're trying to do. My understanding is that you have two lights, one on each side. You want them to be normally on, but blink off when the turn signal on that side is activated. You just need a normally-closed relay for each light. Wire it in series with the light and the constant-power source, and control it with the blinker line. The light stays on all the time, but turns off when the blinker line goes hot. Problem solved.
Yes there is some confusion.

Here's the deal, I have a strip of LEDs I am putting on the bike along each side to increase visibility. Light (1)

I have regular turn signals as well. Light (2)

I want to power light 1, but I also want to use them as huge epic turn signals to make it obvious when I am changing lanes.

The relay got me thinking, and all I have to do is hook a relay up to PS(2) and set it up to DISCONNECT the grounding wire of the LEDs on that particular side (I will need two of these set ups left and right) and when the power goes to the turn signal it will trigger the relay and make the led's shut on and off in sequence with the blinker Problem solved!

Also to make it more interesting I'm going to throw in a daylight sensor so the LEDs are brighter during the day than at night. And I may throw in a tiny capacitor to make the lights fluctuate on and off instead of sharply pulsing on and off.

Thanks for the help guys!

-Dave
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