Does anyone know how to configure a sak215 pulse shapper for a tachometer
I want to make a new tachometer using a old unit but the range of the old unit is different to the new one.
The old unit had a 20mA meter attached to it and the new meter is only 1mA.
A suitable shunt resistor across your new meter would do the job.
It would have to be 1/19 the value of the new meter resistance - perhaps you should measure that
The resistance of the old meter is 156 ohm and the resistance of the new meter is 1000 ohm
Then you need about 53 ohms as a shunt Try a 100 ohm preset and adjust for the correct value
Just tried a 100 ohm across the meter and it gets to about 2000 rpm then stops working
Max rpm is 5000
It's very likely that you driver has a pwm constant voltage output. Try different resistors in parallel with the meter.
Without a detailed circuit diagram circuit it's hard to be certain... what's a sak215?
edit - looked it up. See
it looks like you need to change the resistor on pin 6... and don't shunt the meter..
Here is the datasheet for the sak215
datasheet.pdf (141 KB)
then try changing the resistOr on pin 6 to about 1500 Ohms. And no meter shunt.