# Square Wave to Sawtooth Circuit

Hi All,

I'm in a trouble during some works with wave converting. I want to convert a square wave to sawtooth wave with condition: Same duty cycle, sawtooth maximum voltage should be equal to the maximum voltage of the square wave given. If the square wave is +5 -5, then the sawtooth should also swing in the same voltage level with same duty cycle and phase.

Thanks.

Usually you use the square wave to toggle a constant current source charging a capacitor.

ETA:
Checkout section 7 of this app note:

It is much simpler to generate both at the same time.

If the frequency does not vary, you can use something called an Integrator with an Op Amp. You'll have to trim the resistance to get just the right speed.

Do you mean sawtooth, or triangle? Which wave shape?

If the square wave is +5 -5, then the sawtooth should also swing in the same voltage level with same duty cycle and phase.

The duty cycle and phase shouldn't be a problem... But the voltage is trickier because it depends on the slope of the ramp and and the frequency. (If you change the frequency, you obviously need to change the slope if you want to keep the same voltage.) I assume you'd need some kind of feedback or self-calibration... and a little more design & engineering.

I'd look for a Function Generator chip. Then, you might need an op-amp circuit if you want the signal to swing positive and negative and/or to adjust the bias/offset.

Do you have an oscilloscope? ...If you are going to design a waveform generator it's a good idea to have some way of seeing the waveforms.

There isn't really such a thing as duty cycle for a sawtooth, so I presume you mean a symmetrical triangle wave?

Is the square wave really -5 to +5V, or 0 to 5V?

It might help if you tell us what you are trying to do.

polymorph:
It might help if you tell us what you are trying to do.

I would say that should precede any further discussion.

A 555 might be able to pull off a sawtooth wave..

I thought why not exploit the 555's timing capacitor and feed off of that via a transistor...

Here's my circuit, would that sawtooth wave pass? It's rising edges seem fine but the wave seems a little sharp on it's decent. .

I would say no , because it doesn't look like Polymorphs sawtooth. If you paid \$500 for a function generator
and it gave you a sawtooth that looked like yours , would you be satisfied ?

Well, I did suggest ...

raschemmel:
I would say no , because it doesn't look like Polymorphs sawtooth. If you paid \$500 for a function generator
and it gave you a sawtooth that looked like yours , would you be satisfied ?

If I paid 95c for it, maybe....

http://www.intersil.com/en/products/other-analog/special-analog/other-miscellaneous/ICL8038.html#0.html

There's still a boat load of these left on ebay..

Until the OP tells us more information, there is no point in wasting time on this.

CJDelphi:
The thing missing from the 555 circuit is the constant current source to linearize the slope. otherwise you get an exponential curve.

cjdelphi:
If I paid 95c for it, maybe....

Exactly! That sawtooth is excellent value for the money.

sawtooth 555 attempt 2 lol

s_premkumar999:
I want to convert a square wave to sawtooth wave with condition: Same duty cycle, sawtooth maximum voltage should be equal to the maximum voltage of the square wave given. If the square wave is +5 -5, then the sawtooth should also swing in the same voltage level with same duty cycle and phase.

Bottom line is that there is no way to do this. It involves knowing things that will only happen in the future. The state of the art for ESP electronics is very much in its infancy.