Originally Posted by
Mike.Powell
Looks to me like your gauge is a moving coil style meter likely with an internal resistor to boost the total resistance to roughly 1.5KOhms. Nominal sensitivity is 1 ma full scale.
If you put a standard 3.3KOhm resistor in series with it and connect the resistor to a switched 5 volt source, you should see the gauge swing slightly over full scale. If you put a 1000 microFarad capacitor directly across the gauge, this gives a time constant of about 1 second. (If you use the time constant formula posted earlier, the resistance you use is the parallel combination of the 3.3K series resistor and the 1.5K resistance of the gauge,or about 1K.)
Adjust the value of the 3.3K resistor to change the final deflection of the gauge pointer. I wouldn't go any lower than 3K if you connect to 5 volts. Don't want to toast the gauge.
Adjust the value of the cap to change the time constant. 2000 microFarad will give you 2 seconds, 3000 gives you 3, and so on.