+ and - voltages from a battery

[bob987]

Is it possible to use a 9v battery and run it through some circuit or system to get a squarewave output that has a positive and negative voltage. Ideally the two voltages would be the same but the negative of the other.

 

[KingNothing]

Of course it's possible, but it's not simple. At the most basic level, it would require an oscillator.

Since all voltages are relative, you could easily put two identical resistors in series between your two supply terminals, and call the middle connection "0", and the other two connections "+4.5" and "-4.5". You can increase the absolute voltage difference using capacitors and step-up circuits.

The short, practical answer is to use the +9V as a power supply to a pulse-generating microcontroller or IC, and also as a power supply to some amplifiers which change it's output to whatever voltages you need.

 

[bob987]

Thanks for your reply. So I found this circuit setup that seems to do what I am looking for. here is the link. http://www.555-timer-circuits.com/bi-polar-led-driver.html It uses the LM555 timer, the only thing I'm not sur of is what the freuency of the switching light would be. Would that be determined by the capacitor and 33K resistor or is it more complicated than that?

 

[sophiecentaur]

If you want a 18V peak to peak signal and you are prepared to 'float' your supply or the destination signal (say you want to feed a transformer or loudspeaker) you can use two 'output stages' operating in antiphase, the two 9V squarewaves will have a peak difference of 18V.
This 'push - pull" arrangement was common in audio amplifiers, powered with 12V car batteries. You get 4 times the peak power this way into a given load.

 

[KingNothing]

Thanks for your reply. So I found this circuit setup that seems to do what I am looking for. here is the link. http://www.555-timer-circuits.com/bi-polar-led-driver.html It uses the LM555 timer, the only thing I'm not sur of is what the freuency of the switching light would be. Would that be determined by the capacitor and 33K resistor or is it more complicated than that?

http://en.wikipedia.org/wiki/555_timer_IC#Astable_mode...See the equation for frquency.