Any Electronics types out there? Wave Forms?

[Pete Simmons]

Any suggestions on how to generate a rectangular wave? Low freq and low voltage. 5 or 12 volt peak is fine. around 60 to 200 hrtz.

Not SQ but rectangular where in a series of say 16 waves they grow in size (freq ?) then after 8 or so the shrink back to where it started.

Then generate another identical wave but offset one notch.


Would you do this via hardware?

Software? If software any ideas on output boards to hook to a computer that could do maybe 8 channels?

Or combo maybe a ROM programed like a character generator.

This is just for a little project I am playing with.

Give me some ideas. It has been a long time since I did any work on things like this.

[Lee DeRaud]

Would you do this via hardware?

Software? If software any ideas on output boards to hook to a computer that could do maybe 8 channels?

Or combo maybe a ROM programed like a character generator.

You mean like a wavetable synthesizer? Off the top of my head, it sounds like the easiest way is to program up the sound board/chipset in just about any PC...probably need some analog stuff on the output to get the voltage you need.

I think the Windows multimedia API supports low-level access for stuff like that, but it's been awhile since I looked at it.

[Randy Klein]

Any suggestions on how to generate a rectangular wave? Low freq and low voltage. 5 or 12 volt peak is fine. around 60 to 200 hrtz.

Not SQ but rectangular where in a series of say 16 waves they grow in size (freq ?) then after 8 or so the shrink back to where it started.

Then generate another identical wave but offset one notch.


Would you do this via hardware?

Software? If software any ideas on output boards to hook to a computer that could do maybe 8 channels?

Or combo maybe a ROM programed like a character generator.

This is just for a little project I am playing with.

Give me some ideas. It has been a long time since I did any work on things like this.

Pete, some clarification. grow in size (freq ?) Realize that rectangular waves are actually a sum of (ideally) an infinite amount of frequencies. This is how they get those sharp corners. I assume you mean that you want the waves to increase in the amount of time they are at their peak voltage before returning to zero? Which, incidentally, requires stronger low frequencies.

But semantics aside. What are you using this for and why do you desire rectangular waveforms? There may be an easier way to solve your problem.

[Carl Crout]

Any suggestions on how to generate a rectangular wave? Low freq and low voltage. 5 or 12 volt peak is fine. around 60 to 200 hrtz.

Not SQ but rectangular where in a series of say 16 waves they grow in size (freq ?) then after 8 or so the shrink back to where it started.

Then generate another identical wave but offset one notch.


Would you do this via hardware?

Software? If software any ideas on output boards to hook to a computer that could do maybe 8 channels?


Or combo maybe a ROM programed like a character generator.

This is just for a little project I am playing with.

Give me some ideas. It has been a long time since I did any work on things like this.

The Paralllax BASIC Stamp might could handle that.
try www.parallax.com

[Kent Fitzgerald]

If I'm understanding correctly, you want to generate a train of pulses with a varying duty cycle (i.e., % of time in the high state). This sounds a lot like PWM (pulse-width modulation), which is a commonly used encoding scheme for communication and controls. There may well be a programmable PWM chip that will do what you want off the shelf.

The really nuts-n-bolts approach would be a free-running oscillator to generate a clock frequency, plus a bunch of divide-by counters. Could get complicated pretty quickly.

If you need maxiumum flexibility, software control is probably the way to go.

[David Epperson]

Sounds like standard Pulse Width Modulated wave form from a Variable Freq Drive.