Interesting Electric Projects

[BrianG]

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.

[crazyjr]

I remember an article, in Radio Control Car Action about ten years or more ago where they made a similar device to work on a buggy or truck while radio was impounded

[BrianG]

Lol, I guess I'm a little behind the times then. I just had the parts laying around and thought I would see what I could do. I wish I had an oscilloscope to see how clean the square waves are, but it works.

Very nice.

[Procharged5.0]

Brian,

Typically chips look for 5vdc......is 6vdc a typo or is the ever-popular 555 good with 6V?

[Procharged5.0]

BTW,

The projects are neat. I'd consider building the ESC driver for myself. It could be handy.

[BrianG]

Thanks! This is the type of thing I do when I have extra time on my hands (and not enough money to make a new BL setup). :027:

Typically, a 555 timer can run from 5v all the way up to 18v IIRC. If you want to make it for steering and throttle, use a 556, which is just two 555's in one package. Since the frequency is not very high (~60Hz), there is not much concern about noise or component placement, so a perfboard works fine. I hate the time it takes to etch my own PCBs; masking, etching, cleaning, drilling. Ugg.

[Procharged5.0]

Agreed. Just the time involved and the mess with the etchant.....

not worth the time on a mini project.

Do you happen to have a schematic of the Steering & ESC using the 556?

[glassdoctor]

Can you paot a pic of one? It looks simple enough even for me to do. :)

[BrianG]

No, no schematic of a 556 circuit. Really, the only thing you gain is price (one 556 is cheaper than two 555's) and you only need one power and ground for the IC. For simplicity, symmetry, and/or future growth, using two is just fine.

GD: No, I didn't take a picture of it. I had it laid out on my experimentor board so it wasn't pretty. :) I will say it is easy to put together though. Just a matter of planning the component layout for minimal wire jumpers from each component to the pins on the 555.

[Procharged5.0]

[QUOTE=BrianG]No, no schematic of a 556 circuit. Really, the only thing you gain is price (one 556 is cheaper than two 555's) and you only need one power and ground for the IC. For simplicity, symmetry, and/or future growth, using two is just fine.

QUOTE]

Thanks,

I could draw it up.....I was just being lazy! :027:

[glassdoctor]

Cool... I'm thinking no board, just a mess of wires and hot glue for me. :)

[Procharged5.0]

or pot the whole mess! LOL!

I'm envisioning a little epoxy cube with a bunch of wires hanging out! LOL!