Re: pulse generator

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "toolmkr" <dkmach2@...> wrote:

>
> Hello,
> I am setting up a stepper motor to drive a mechanism at variable
> speeds, 0-60 rpm Spec sheets for the motor and driver can be found on Anaheim Automation web site, the motor model is 34Y214S-LW8 and the driver model is MBC10641. The tech support person at Anaheim Automation advised me that I would need to purchase an external "pulse generator" in order to make the setup work as I would like. I need to be able to change the speed of the stepper motor on-the-fly without having it connected to a computer by simply turning a knob such as on a potentiometer.
> He told me I would be able to pick up a pulse generator from Radio Shack, however I was at the store and they were not too helpful.
> Any assistance would be appreciated.
>
> Sincerely,
> Denis

Depending on wheather you need direction as well as variable speed the 555 circut will work. At those speeds (really low RPM) there will be a degree of vibration even with microstepping. We have a conveyor oven for surface mount PCB's with a stepper turning a gear reduction and using a 555 circuit. It vibrates.

You you want a wider range of frequencies with a 50% duty cycle then the CD4046 (74HCT4046) is a VCO (voltage controlled oscillator) that uses a single cap and resistor (pot) to sweep across a wide range. It also allows you to put in an acceleration curve by putting a cap in the voltage input pin. Getting 0 RPM (no pulses) is harder with either circuit because at really low pulse rates the circuit get unstable.

Any direction needs to come from a switch unless you want to add a lot more circuitry.

>