I am looking to put together a small circuit to activate red led lights on my R/C truck but I am unsure as to the components that would be required, especially how to work out when the brakes are being applied. Any help is appreciated.
Thanks
// ___ +---->|----|___|-+ | led 220 | | | --- | - | | / | +-----o o-------+ break switch
I do not know where you can get a foot small enough to press the break pedel !
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We're gonna need to know a lot more about your truck. Like, *anything at all* would be a good place to start.
You have a receiver on the truck that outputs a control voltage to the brake? Are the brakes proportional control (press harder - move joystick further does it stop faster?)
If the brakes aren't proportional - either on or off just wire the LED to the brakes.
If the braking is regenerative (motor supplies braking torque) that's a different ball game entirely - more information would help.
If you do use regenerative or "electronic" braking you'd need to sense the drive motor signal and light an LED when the motor was off or in reverse mode.
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On Tue, 9 Dec 2003 15:57:44 -0500, "Mark Webber" wroth:
My old Schwin "Black Phantom" bike (I really wish I still had it) had brake lights built in. They used a switch that sensed when the bike slowed down (for whatever reason) and turned the light on. They used a small plastic tube with a brass ball in it that could roll from one end to the other. The tube was mounted horizontally with a pivot near the center. Picture a little cannon like they show on the Bugs Bunny cartoons. The tube is capped at each end. The end toward the front has a couple of contacts with flexible wires attached built in. The tube has a stop under the front end so that it can't pivot all the way level. It's still pointed up a little bit when the ball rolls toward the front because the bike is stopping. Once the bike is still, the ball runs to the back end again.
So simple it HAS to work.
Jim
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Simplest solution is probably a mercury switch that is set to "tilt" when the truck slows down.
I did this once, by monitoring the signal to the throttle and brake servo. The signal to the servo is a series of pulses which vary in width, you can average them out with an RC time constant and compare them to a reference voltage to drive the brake lights.
-- If the pulses go away when no braking signal is present _and_ they're constant frequency but variable width, then all you need to do is use a retriggerable one-shot with a period slightly longer than the time between two pulse leading edges to drive the LEDs.
Hi Mark,
Model transmitters, recievers and servos work on a pulse system. The pulse width varies in proportion to the control position on the transmitter (example: full left = 1mS, full right =2mS and center = 1.5mS).
You can buy small electronic switches that will do exactly what but they are hard to track down. Try asking if somone can recommend a small "Electronic switch" on the forum here...
Colin
-- Even when you're coasting downhill with the brakes off?^)
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