Hi
I would very much like to have a analog output from 0 V to 10 V(*). It dosn't need to draw much current. I was wondering whether it could be done by connecting two analog outputs to get 0 - 10 V (in serial), or should I amplify one 5 V analog signal?
(*) I'm modding a wheelchair and my first thought was to keep it as simple as possible and emulate the signal from the wheelchair joystick (6 V = neutral, 7V = full forward, 5 V = full backwards).
Kind Regards
Yenn
Eeeeeew. That's an obnoxious thing that you have to emulate - who uses analog signals above logic level in that way?
First off: The Arduino Uno cannot produce true analog output. The analog outputs are PWM (switching between 0v and Vcc with variable duty cycle). Make sure that your wheelchair will be happy with PWM (some things will, some things won't)
The arduino also cannot produce output higher than 5v, and can be damaged if any of the IO pins are exposed to such voltages.
If you have, say, 12v, I'd divide it in half to get the 6v for no movement. Then, I'd connect it to the collector of NPN transistor through a resistor of value such that it would pull voltage down to 5v when the transistor was on, and then do the same thing for the high side with a PNP transistor. Put a small cap from that to ground to smooth out the signal.
In all cases, you'll need to keep an eye on the current, and size the resistors appropriately. Make sure to measure the current on that control wire.
Another approach would be to use a digital potentiometer, but that's not viable unless you're drawing virtually no current. You'll need to check around for a digital potentiometer that will accept that voltage range (most are 0-5v only) - I know there are expensive ones available in TSSOP-14 (ie, hard to solder) that go up to 36v, and I think I saw some that went to 15v in friendlier packages.
VektorLektor:
(*) I'm modding a wheelchair and my first thought was to keep it as simple as possible and emulate the signal from the wheelchair joystick (6 V = neutral, 7V = full forward, 5 V = full backwards).
Can I assume from that, that about 6.5 volts will give half speed forward, etc.?
If so, then the joystick is operating a potentiometer. Could you emulate that by using a similar pot driven by a servo?
If the joystick is just activating switches, you could emulate it with a couple of relays or transistors, depending on the current drawn, and voltage dividers
Get your Gnd and 10V from the electronics already present in the wheelchair.