Re: [CAD_CAM_EDM_DRO] stepper issues

How fast does it run in hz ? The step rate I mean.
You may be into mid-band resonance. Probable even - old round steppers,
yes ?
How many rpm does the motor turn at 9.6 V ?

If you slow down your step rate, resonance will go away.

I think I remember that for your use, its more important to get accurate
than to get fast.


ebiz_59 wrote:

>
> Thanks for all you help so far. I'm working with a high school
> freshman to get a stepper motor to run a certain number of steps and
> then stop - calibrate a small erector set car to run between 5 and 10
> meters (we'll be told specific distance at the competition) and then stop.
>
> We have combined 2 basic circuits to accomplish this task - a 555 as
> monostable (adjustable time) dumping into a 555 astable to give steps
> while monostable is saying "go" and the astable dumps into the trigger
> of a 5804.
>
> We get this circuit to drive a stacked can motor - we need like 30 to
> 45 seconds of run time. We don't have it hooked to the device yet -
> the motor is just driving another free running gear. The motor starts
> alright, but sometimes well into the run, it gets confused and
> stalls/reverses.
>
> A few notes about stuff we might have done wrong -
> 1 - we didn't use pullup/down resistors for the full, half, direction
> pins - we just tied them to +5 or gnd.
> 2 - we hard wired this on an soldered experiment board and have wires
> going everywhere. We initially did 3 circuits on 3 separate
> breadboards and had the same problem. I thought it might be the
> breadboards and the fact that we could only put about 7 V to the motor
> circuit, but we get the same results with a wired cicuit all on 1
> soldered breadboard and 9.6 V battery running the motors and dropped
> down through a 7805 to run the 555's and 5804.
> 3 - we are limited to 9.6 V max by the rules
> 4 - we didn't use a PIC for a couple reasons - I wanted him to learn
> about 555's, we didn't have PIC programmer in stock so I thought I'd
> have him work on the 555 path while I researched and acquired
> programmer - still hope to do this, but the competition that sparked
> this project is Tues, Nov 20, so we are trying desparately to get this
> circuit to work.
>
> We'd sure appreciate your help in where to look.
>
> Thanks again for your help so far, and for any you can give over the
> next few hours/days.
>
> Chuck
>
>