Brake lights for the Yeti 1/10 (RTR)

[Phaeton]

The Yeti has four lights at the back. Had the idea of configuring the outer two as permanent on and the inner two as brake lights. The outer two with normal red led's and the inner two with blinking red led's.

(By the way, this is mine)

So I needed a "contact" that closes a circuit when a certain amount of g-forces is exceeded.

A tube with a spring is a possibility, but that is mechanical and subject to dirt and beatings as a result of the environment in which we drive our cars.

Then I found a commercially available little circuitboard that has a G meter onboard. It can measure G forces in X and Y axes. When in rest (0 G), the output is 1.65 Volt. The output increases in a linear way and is 2.31 Volt when the G force is 1 G.
With a margin for bumps, the brake lights should be switched on at about 0.3 G. That would be 1.85 Volt. But that should be adjustable.

So when I add a component that closes a circuit (the circuit that "feeds" the brake light led's) above that 1.85 Volt and is also adjustable, then I have my brake light switch. And brake lights.

That component is a simpel opamp. Used pins:
The + which "feeds" the output
The - or general mass
The output voltage of the G meter circuitboard
A reference voltage
The output voltage

Todo:
Put everything together so that when the output voltage of the G meter circuitboard is lower than the reference voltage, the opamp keeps the circuit which "feeds" the led's open and no brake lights will lit.
When the output voltage of the G meter circuitboard is higher than the reference voltage, the circuit is closed and the brake lights will lit.

Done.

With a simple opamp and a voltage divider circuit. The module with everything put together will be installed in the dummy fuel cell.
There is a red wire-loop outside the module. That is for later when I install a remote controllable relais to switch the permanent light's on and off. Easy to modify later that way. Yes, the design is future compliant

In the image the module from left to right:

• 3-pin connector for +, - and signal. Signal is later used for that mini-relais.
• The G meter circuit board.
• The 10K potmeter as part of the voltage divider. The other part, a 2K2 resistor, is under the opamp.
• Above the potmeter is the opamp. I used a LM324.
• The 3-pin output connector for the wires that go to the body and then to the led's. 3 pins, general +, the + for the brake lights and a pin for the mass.
• Allover: Some wires to tie everything together.

The module works perfectly, will wire the led's into the Yeti this weekend, charge the helmet cam and post a little movie of the working brake lights.

Yvo


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[Phaeton]

All done.

New head lights, permanent red taillights and orange brake lights lit when forward G forces are applied (in this case in the "lab", when the Yeti is tilted forward).

(I seemed to be out of blinking red leds)

Movie t̶o̶m̶o̶r̶r̶o̶w̶. Next week.

Yvo


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[Brainanator]

Awesome! I'm interested in trying to replicate this with my rudimentary knowledge. Anyway you can give more info on where to find the G meter?

[Phaeton]

The integrated module can be found here and I modified the alarm clock schematics.

The reference voltage has to be calculated correctly, the alarm clock example doesn't work. So use this one.

In the meantime I replaced my module already. It was fun building and trying it, but the Yeti comes to a halt under two seconds, so the brake lights look more like lights with loose contacts, just bleeping shortly

But the build is fun

Yvo

[Brainanator]

Thanks for the info! Appreciate it.