Hi,

I need a a circuit in which I can output between -9v and +9v. Is it possible to use 2 9v batteries in series and a pot with the centre point set as 0v?

I have some of those little PlayStation thumb joysticks in which the center point is 2.5v for a 5v input and then one direction is 2.5v to 0v the other 2.5v to 5v.

Any help appreciated. Thanks

 

Hi,

I need a a circuit in which I can output between -9v and +9v. Is it possible to use 2 9v batteries in series and a pot with the centre point set as 0v?

yes.. see here..
http://www.learningaboutelectronics.com/Articles/Dual-polarity-power-supply-circuit.php

 

You could possibly use a pot and two 9V batteries for that, depending upon how much current to want out of the pot.
What will be the load for the pot output?

 

yes.. see here..
http://www.learningaboutelectronics.com/Articles/Dual-polarity-power-supply-circuit.php

That article appears to be a bunch of hooey.
It talks about making a dual supply from a single supply (although it shows a dual supply in the picture), which is not possible as shown.
It says to use "really any DC power supply as long as it has 3 terminals: +, GND, -."
The won't work since that GND terminal is normally chassis ground, not a center tap circuit ground, as the author apparently assumes.

 

Hi,

I need a a circuit in which I can output between -9v and +9v. Is it possible to use 2 9v batteries in series and a pot with the centre point set as 0v?

That is exactly what I use to test ±10vdc analogue input servo drives.
Max.

 

That article appears to be a bunch of hooey.
It talks about making a dual supply from a single supply (although it shows a dual supply in the picture), which is not possible as shown.
It says to use "really any DC power supply as long as it has 3 terminals: +, GND, -."
The won't work since that GND terminal is normally chassis ground, not a center tap circuit ground, as the author apparently assumes.

I didn't read the article.. I should have just posted the image on it... and said replace 15V with 9V batteries

 

That is exactly what I use to test ±10vdc analogue input servo drives.
Max.

That's exactly what it's for Max! Good effort. Got a set of old analog servo drives I need to test.

Current from one 9v battery is enough to operate the drive. At the minute I'm just using one 9v battery and a pot to vary between 0 and +9v. Then I have to swap the polarity round to reverse the motor. I don't need any sophisticated circuit design for this. Just a way to vary between -9v and +9v using 2 batteries.

Unsure how to go about wiring a pot into this?

 

You wire the batteries in series, with the pot across the 'outer' terminals, The common (ov) point is the junction point of the batteries, the ±10vdc is the slider of the Pot.
Max..

 

Ideal, thanks Max!