Hi all,
I'm trying to build a simple circuit that would generate ac signal from a 5v powered microprocessor. Power is an issue since the device is small and the power budget is critical.

As a starter a square +/- 2.5v pulse will do, but ideally i would like to be able to generate +/- 5v from the same micro.

I was thinking of generating the 0-5v pulses and also using a 2.5v switched voltage regulator - this way if i provide the 2.5v as "GND" to the outside (2 electrodes which should see my pulse) and the micro pin with the 0-5v pulse on it, i will get a +/- 2.5v .

The problem with it that all the voltage regulators i have encountered until now can only source current, not sink it, (they specify that they have reverse current protection) so when the micro generates signal less than 2.5v, there is no current flowing since the regulator won't sink it.

I would appreciate if people could share their thoughts on this - what would be the correct way of achieving my goal ?

I appreciate all advice,
Thanks in advance,
Lenny

 

Use a MAX232 or similar chip.

 

You might take a look at this page:
http://en.wikipedia.org/wiki/Voltage_multiplier

The Dickson charge pump about halfway down is good with microcontrollers. But note that you can only get a tiny amount of power through one of these things.

 

How much current will you want to draw from this circuit?

What about a simple capacitor?

If you connect your 0-5 volt pulse to a capacitor, and the other end of the capacitor is grounded using a high value resistor, like a megohm, then you will see +/- 2.5 volts across the meg resistor, but it won't be able to supply much current.

 

Thanks for the replies guys.

The circuit does need to provide some current, in the 50ma-100ma range,
so the capacitor idea sounds like it might work,

I think i could connect one leg of the cap to the +/-2.5v pulse and the other
to ground and picking a big enough cap will let me have very little voltage drop during the pulse.

Dave, thanks for the advice on that one.

How about a sine wave, say I want to apply a sine wave pulse, I don't see how a cap can be used in this configuration ?

Thanks again,
Lenny

 

Dear friend
I had project which made Sin,square ,and triangle wave with 0-4 Volt as amplitude.the rang of frequency is 10KHZ-100khz.I do it by At-mega 32.if this project help you,tell me to introduce it for you.
Best Regard

 

Dear Cyrus,

I would really appreciate if you introduced me to your project,
it would be of great help. my email is lenny_m@mail.ru, you can email me directly if you prefer.
Thanks !

Kind regards,
Lenny

 

dear Friend
I know it & and i don't do that.i just say my answer to this post.and i suggest that if this project (which i was don it before) help you tel me to introduce it.

 

Cyrus , i'm not sure i understand, but if you could send me a link, it would be great.
thanks.

Lenny

 

on whole.my project was a kind of signal generator withe specifications that I said.

 

I mail a video for you.did you get it?