I still don't get it, an Analog meter (moving coil meter ) have 2 lead only, but this have 3 lead... and is it because of this, the pointer of meter will be very stable, not moving out much even a vibration shock during car drive, am I right? Where can I get more info about this kind of meter?
In my old truck there are two answers for why three “inputs”.
1. Some of the meters have three leads but only 2 are used.
2. Two of the meters have leads labeled “gnd”, “+” and “S”. The meter needs power and ground to work and one wire that goes to the sender. If you look at the Moving_coil_meter link they show a magnet. It could be made with a electro-magnet that requires power.
thanks for reply, I have open up the meter, I notice it is moving magnet, the coil with 3 lead is fix unmoveable.
And yes, there is (+) and (Gnd) connect to two lead of the coil through resistor.
But to control the meter, what shall I input to (S)? a resistor to ground or a small voltage input?
Here I attached more photo for better understanding.
Thank you,