RC plane motor questions

A real programmer would use binary :-)

Not since John Von Neumann met the ENIAC...

Then I was a "real" programmer until I got tired of flipping switches and wired in an octal keypad. You would have posted in Morse from your home-built ham station.

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The purpose of my gyros is to do the actual stabilising. The gyros used in helicopters are sensors. In my Sony camera is some type of physical lens positioning system that uses some type of motion sensor for positioning info. However, it is not enough for more violent shaking. I have a relative who loves to take pictures but has hands that now shake so much that some type of stabiliser might really help. Eric

I know how to control a servo with a microcontoller. The 555 solution is, I believe, cheaper. Eric

maybe, but not by more than a buck or so.

Thanks for the starting advive Tim. As for controlling speed, it's not the brake that's controlling the speed. The motor will need to spin at some determined speed but the driven wheel will sometimes be subjected braking forces and when these forces diminish the wheel must resume the determined speed smoothly. Thanks, Eric

I bought a Basic Stamp kit from Parallax and learned how to control servos with a microcontroller. I'm not sure how use a pot to vary the pulse output rate from the stamp. But I can do this easily with a 555. If I needed hundreds of motor drivers I wonder what would be the best way to go. If I just wanted to control no load speed and direction without any type of feedback from the motor could a microcontroller do that by using power transistors? Easily and cheaply? Since I haven't even ordered a motor and ESC yet these questions may be premature. Eric

Just to toss an alternative out there, they are making gyros for RC planes that attach between the servo and the receiver, the gyro senses the movement and automatically moves the servo to compensate. Wouldn't quite do the same thing, but could be useful at some point.

I have a few micro planes that use pager motors for the prop, and yes, their life is not very long.

Now there is a pager-motor as plane-motor that lasts quite well, that is for a solo-pro helicopter.

Dave

These motors cannot practically be driven without feedback, but you could very well use the micro to handle the feedback as well. In fact, all the commercial ESCs I have seen close up use not much more than an Atmel microcontroller and a bunch of power MOSFETs to do the job. If you had access to the firmware, you could simply modify it to read a potentiometer directly in stead of reading the pulses from the RC receiver.

If you want to build your own, you can find several open designs where both hardware drawings and source code is freely available.

Why bother with a pot? Actually, there are several solid state 3-axis accelerometers available. Parallax has one - pretty reasonably priced.

Yeah, that's right, I was getting confused between my car speed controls and heli speed controls. The car reversible speed control automatically sets the zero speed on power up, this is because some transmitters have 50/50 forward reverse, some have 70/30 or somewhere around there. The heli speed controls start flashing and disable if they are above zero throttle. I haven't measured the pulse width connected to a speed control so I don't know if zero speed is 1ms or 2ms pulse. One of my heli speed controls has a governor, that might be nice for gyroscopes.

RogerN

I actually met a bloke that had worked on computers where to boot you had to enter a small "read that and do something about it" routine on the front panel.

If you're getting by with pagers motors, I think these RC type motors are probalby way too big for what you need. astroflight.com does have some smaller motors these days. maxcim.com has some of the largest ones.

for precision tiny motors, check out

pancake type motors can be used AS flywheels too- try to get a motor from a DLT tape drive. they're really nice.

Maybe you can make some sort of magnetic coupling as used in pumps.

In brushless motor fans, they have what's called "locked rotor protection". If the motor stalls, the driver circuit pretty much gives up and doesn't output full power, waits a second or two and tries to start the fan again to see if the fault clears. They usually do this forever without burning out.

Some induction motors are "impedance protected" and won't burn out if stalled as their impedance is high enough that they can't draw enough power to burst into flames in the first place.

I'm a bloke who designed and built one. The manually entered bootstrap loader was a 32 byte loop that read in a Teletype tape, downwards so the final byte overwrote a jump destination to start the monitor program, which was a very simple operating system that could load more code from paper or magnetic tape.

IIRC the bootstrap loader began with a conditional jump to the monitor that wasn't true at cold start. The paper tape boot program changed it to JMP to skip the bootstrap loader at subsequent resets.

jsw

The Okuma OSP-2000 cnc control loaded with boot strap loader loop. You first have to manually set in about 21 bytes of code using switches to set up the computer to run the bootstrap from a short punch tape. Once you load the bootstrap the actual executive system tapes can be loaded. These machines used two 8K bubble memory boards. The newer options went with a cmos memory.

John