I need to make a portable test box which gives a selectable dc voltage output - 4v, 10v and 13v. Anybody know the best way to do this? I was thinking maybe two 9v batteries and then using a 3 way switch and resistors to reduce the voltage. Or maybe a potentiometer would be easier? The output voltage is just being used as a reference, so the current draw will be very low. To explain - I have an alarm panel that monitors sensors - the sensors give 10v when healthy, 13v when they are faulty and 4v when they have sensed. I want to test the alarm panel by mimicking a sensor in each of the conditions. Thanks in advance for any feedback
I think both of your ideas would work fine as long as you know approximately what the current is. Using a potentiometer is the simplest way but resistors permit a higher currentflow. If you use a pot you could put a resistor in series so you don't burn it. The safest way is using an adjustable linear regulator like the LM317. These are commonly available as cheap kits in electronic stores and can also be used in a wide variety of other experiments. Two 9v batteries in series would work fine.
