I have a pressure switch that puts out 0 to 5 VDC. I need to convert this signal to a square wave but I'm not sure how to go about doing it. Do I have to convert it to AC then to a square wave? or can i go from DC to square wave? I recently developed a interest in electronics so my knowledge of the subject is limited. Any help would be great.

 

What is the frequency range that you need? You may be able to program a cheap microcontroller to do what you need. Search for Arduino, they might have an existing design/program that does what you need. There are also IC's that convert voltage to frequency, I think National Semiconductor makes one.

http://www.national.com/ds/LM/LM231.pdf

 

Does the 0-5V vary in an analog fashion from zero to five volts or is it either 0 volts or 5 volts as suggested by your use of the term 'switch'? If it is in fact a pressure switch it should easily provide a square wavepretty much directly. A little more information on the functionality you want/need would be helpful in order to give you some helpful direction.

 

Here's a link to the data sheet for the pressure sensor. I just need a variable duty cycle from 50% to 90% at 500Hz. I'll have to double check the frequency but I believe 500Hz is correct.
http://cache.freescale.com/files/se...ALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation
In the OP I said pressure switch when in fact it's a pressure sensor. My apologies.

 

You are not making square waves. You are generating a PWM (pulse width modulation) signal. The duty cycle of a square wave is fixed at 50%.
This chip will generate a fixed frequency 0-100% variable duty cycle signal from a 0-5 volt input:

http://www.maxim-ic.com/app-notes/index.mvp/id/4502

You will need to massage the 0-5v input to limit the PWM output to your desired range of 50-90%. As shown, it runs at 500Hz. That can be changed by choosing different R's and C's.

You can get free samples of this chip from Maxim.

 

You could probably just use a 555 timer in astable mode, couldn't you? It would be a lot simpler. I can post a simple PWM circuit, if you're interested.
Der Strom

 

You could probably just use a 555 timer in astable mode, couldn't you? It would be a lot simpler. I can post a simple PWM circuit, if you're interested.
Der Strom

I am interested.

 

I am interested.

That offer was 3 1/2 years old. Why don't you start a new thread and tell us what you need.

 

Hi Jessica,

As pointed out, this thread is quite old. However, seeing as this is still on-topic I will go ahead and post it.

Here is the PWM circuit I generally use. It is based around a 555 timer and a 393 comparator:

The specifics are on this page:

http://www.rmcybernetics.com/projects/DIY_Devices/homemade_pulse_controller.htm

It is possible to create a PWM circuit with just one 555 timer, but it is much less accurate, and the frequency and duty cycle are not adjustable independently. I have found this circuit to be far superior.

Hope this helps!
Regards,
Matt

 

It does help, it does... except I figured out the problem in my original design---<snip> misconnected wire. TT

Thank-you so much for restoring my faith in the 555 timer. All roads lead to... well, this design.

Edit: deleted expletive.

 

It does help, it does... except I figured out the problem in my original design---******* misconnected wire. TT

Thank-you so much for restoring my faith in the 555 timer. All roads lead to... well, this design.

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