[maxslomoff]

I want to build something that can slide a heavy weight slowly back and forth, with a pause at each end. The travel distance needs to be between 4-10 ft. the weight would be all attached to a flat frame that I can hang from heavy duty channels and bearings - so this frame would be supported by other means, but I need a motor that is strong enough to push and pull it along its tracks. (any where between 100-600 lb.)

Bonus's would be
*adjustable travel distance
*adjustable speed
*adjustable pause time at each end

I was trying to investigate hacking a garage door opener, thinking I could make a physical switch at each end that could press the button and send it in the other direction... but then I started reading about motor controllers, and stepper motors and servo motors and I'm lost. In way over my head.

Do you have any words of wisdom for me? Any ideas you think I should explore?

[jcaron2]

You could probably reuse the motor and mechanicals from a garage door opener, but it might be tough to try to adapt the electronics. It's true that you could try to kluge some sort of "ballet of button pushes" to try to trick the thing into operating the way you want it to, but it also may be easier to just do the circuitry from scratch.

How much experience do you have with circuits? A couple of op-amps or 555 timers would go a long way toward doing what you're trying to do. After that, it may just be a few relays or power transistors to run the motor (which could probably be bastardized from the garage door opener as well). I'm happy to help if you want to go down that road, but it would be really helpful if you have some electronics experience and some equipment (like an oscilloscope - not 100% necessary but definitely a big help). Otherwise, maybe you really would be better off trying to rig something mechanical to push the buttons.

As far as speed control goes, it depends on the motor but if I had to take a wild guess, I'd say a garage door opener probably uses a simple universal motor like you'd have in a power drill or a hand-held circular saw. Such motors can operate off AC or DC, and their speed is controlled by the voltage. You quite could use a simple dimmer switch like you'd use for a light to control the AC voltage going to the motor's power circuitry, thereby controlling the speed.

[maxslomoff]

Thanks jcaron2,
I don't have an oscilloscope, but I may be able to hunt one down for temporary use.
My electronics is really rusty by now. In high school I studied electronics and built a motion detector circuit. I know about electricity from construction work... but I haven't designed any circuits since.

I'm sure with some imparted wisdom I could make the circuit- I'd love to do that because achieving all the bonus goals would really make it worth while. I would need help with the design though.

I started to read up on op-amps and 555 timers, but its late and I can't seem to figure out how to implement them. I will try again with a fresh brain.

Shall we continue our discussion here or by email? My email is maxslomoff at gmail

[jcaron2]

I'll send you an email.