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BrianG · 11:48 AM

I've been busy in my basement making a few things and thought I'd share. :)

Servo/ESC driver:

Using a 555 timer IC, I made a really simple circuit that will control a servo or speed controller without having to use a receiver/transmitter. You just hook up the servo and adjust a pot to make the servo move back and forth. It also works on a speed control as well, at least on the Quark and Mamba Max I have.

Seems a little useless to some, but I thought about making a BL powered large power-wheels type of thing where my kid can sit in it and ride around. But then, a simple flip of a switch to turn the control over to my transmitter (and gearing up), he can get out and I can use it at a much faster speed. Sort of a 1/3 to 1/4 scale vehicle.

As you can see, it's quite simple. All you need is two of these to control steering and throttle. The frequency is about 56Hz. Min is around 0.85ms, max is around 2.5ms.

LED Pit Lamp:

I had a bunch (100) of high brightness white LEDs around so I thought I'd see what they would do if I got 75 of them hooked up. I wanted to make it run off 12v so I can either use batteries, car voltage, or my charger power supply. But, at 12v, I can only get 3 LEDs in a string (each LED needs about 3.2v). For 75 LEDs, that's 25 strings! Ugg, what a wiring mess.

So, I built a switching power supply that converts 12v DC into about 54v DC. This lets me use 15 LEDs in one string. For 75 LEDs, that's only 5 strings. I then built a constant current source for each string so each gets exactly 20mA no matter what the supply voltage is.

The transformer came from a broken 60w cigarette-lighter inverter and is quite small. My circuit runs at about 14kHz and is right around 77% efficient. Not bad, but I was shooting for at least 80%. Oh well. It is very bright and easily lights up a workarea, but is kinda focused on one area. I just have to build some type of enclosure for it now.

Since I still have about 20 LEDs left, I'll probably make headlights for the Revo for bling. :) It will be designed to run at any pack voltage from 14v up to at least 30v, and will only pull 0.04A so it will hardly affect runtime.

	(#1)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	Interesting Electric Projects - 01.14.2007, 12:57 AM I've been busy in my basement making a few things and thought I'd share. :) Servo/ESC driver: Using a 555 timer IC, I made a really simple circuit that will control a servo or speed controller without having to use a receiver/transmitter. You just hook up the servo and adjust a pot to make the servo move back and forth. It also works on a speed control as well, at least on the Quark and Mamba Max I have. Seems a little useless to some, but I thought about making a BL powered large power-wheels type of thing where my kid can sit in it and ride around. But then, a simple flip of a switch to turn the control over to my transmitter (and gearing up), he can get out and I can use it at a much faster speed. Sort of a 1/3 to 1/4 scale vehicle. As you can see, it's quite simple. All you need is two of these to control steering and throttle. The frequency is about 56Hz. Min is around 0.85ms, max is around 2.5ms. LED Pit Lamp: I had a bunch (100) of high brightness white LEDs around so I thought I'd see what they would do if I got 75 of them hooked up. I wanted to make it run off 12v so I can either use batteries, car voltage, or my charger power supply. But, at 12v, I can only get 3 LEDs in a string (each LED needs about 3.2v). For 75 LEDs, that's 25 strings! Ugg, what a wiring mess. So, I built a switching power supply that converts 12v DC into about 54v DC. This lets me use 15 LEDs in one string. For 75 LEDs, that's only 5 strings. I then built a constant current source for each string so each gets exactly 20mA no matter what the supply voltage is. The transformer came from a broken 60w cigarette-lighter inverter and is quite small. My circuit runs at about 14kHz and is right around 77% efficient. Not bad, but I was shooting for at least 80%. Oh well. It is very bright and easily lights up a workarea, but is kinda focused on one area. I just have to build some type of enclosure for it now. Since I still have about 20 LEDs left, I'll probably make headlights for the Revo for bling. :) It will be designed to run at any pack voltage from 14v up to at least 30v, and will only pull 0.04A so it will hardly affect runtime. Last edited by BrianG; 06.09.2009 at 11:48 AM.