Lighting controlled by engine's RPMs

[dragwindsor]

Hey guys, new here.

I have this idea to put red LED lighting in the engine area of my Honda sportbike, but not in the normal fashion.

I'm trying to figure out if it's possible to hook the lighting up to the bike, or engine, in such a way, that when I'm idling, the lighting is barely on, and as I increase RPMs they would get equally brighter.

Kind of like the old bicycle lights that contacted the tire, the faster you went, the brighter they were.

If anyone can help me out, I'd really appreciate it.

Thanks

 

[crutschow]

You could tap into the digital pulses going to the tach. Use those to trigger a one-shot (555) that will pulse the LEDs. The faster the pulses, the brighter the LEDs.

You'd have to measure the frequency of the tachometer pulses to determine how long the one-shot period should be. I expect they occur at the spark rate for two cylinders or once per revolution.

 

[dragwindsor]

Thanks alot. I'm relieved to see that it's actually possible.

I'm not really versed in circuit building, so could you point me in the right direction to buy an appropriate timer, and LED's?

I'm not exactly sure what I need as far as timer specs. I tried searching, but I only found circuit diagrams.

I'll research how to patch in and count the digital pulses.

I hate asking for such direct help, but I'm WAY out of my element here.

Thanks alot, even if you can't help.

 

[dragwindsor]

I'll attempt to build the circuit, but I have NO idea where to start. Would I be able to find a diagram, or......? I don't even know where to start.

I hate asking for stuff like this, but I've searched everywhere, you guys seem to be my best bet.

Again, thanks alot.

 

[Diver300]

If you connect to the alternator, before the rectifiers, you get a voltage with a frequency that varies in proportion to the engine speed. You can take as much power from that as you want.

 

[dragwindsor]

It's a motorcycle without an alternator. Fuel injected - ECU. Fully transistorized ignition with electronic advance.

 

[crutschow]

It's a motorcycle without an alternator. Fuel injected - ECU. Fully transistorized ignition with electronic advance.

It has no battery?

 

[dragwindsor]

It has a battery, but it doesn't have an alternator. My current bike is a 2008 Honda CBR125R. Single cylinder, liquid cooled, 4 stroke. I'm not sure how the charging system works, but I think the digital pulses from the tach is the way to go.

 

[dragwindsor]

Correction, it DOES have an alternator.

 

[dragwindsor]

Bump_anyone>?_

 

[danrogers]

i was going to say, a bike with a battery you have to charge off the mains lol.

as suggested i would start by finding out a way of measuring the frequency being produced by the alternator, it would be directly proportional to crank speed.

once you know that you could have a sensing circuit with a timer ic or pic running the LEDs in PWM

 

[ParkingLotLust]

You could try taking a signal from one of the spark plug wires - that should give you a spike when you get a spark, and with some filtering, I bet that would let you calculate RPM. Just a thought.