Simpson Vom


VOM stands for Volt-Ohm-Milliammeter, a multimeter that uses switches to reconfigure a sensitive mechanical meter movement for an assortment of measurements. The Simpson 260 was the category leader when I purchased mine in 1967.

    

See the awesome Simpson 260 site for pictures of the entire line. I have a 260 series 5.


I dug out my trusty Simpson to debug the SpinometerProject. I found I could read variables to two digits of accuracy which was enough to find my bugs.

Here is a meter test program I wrote to study the accuracy and linearity of this and other meters I've since used as ArduinoBoard output devices.

    byte steps[] = {0, 1, 2, 3, 4, 5, 4, 3, 2, 1};

void loop () { meter(9, steps[millis()/1000L%10, 5); }

void meter(int pin, float value, float scale) { float volts = value * 2.5 / scale; // use 2.5v scale int pwm = volts * 255 / 4.82; // output <= ~5v analogWrite(pin, pwm); }


 

Last edited January 4, 2009
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