potentiometer :
switch :
You can't hook up a switch directly to the BrainStem without adding a resistor in line with the ground. This prevents the switch from drawing too much power by using a "pull-up" resistor in the following configuration.
- the power lead (red) is attached to one side of the switch
- the signal (white) is attached directly to the other side of the switch
- a 10K ohm resistor is attached to the same side of the switch as the signal
- the ground (black) is then attached to the other end of the resistor
switch pole 1: --------------------------- power (red) ----- brainstem
switch pole 2: --------------------------- signal (white) -- brainstem
\---- 10K ohm resistor ---- ground (black) -- brainstem
Normally, you should use a single pole, single throw (SPST) switch. You can use either a momentary switch or a toggle switch. The momentary switch only makes contact while you depress it. The toggle switch holds it position in either on or off position.
This same technique works for other passive sensors that come with only two wires, for example, pressure sensors.
