Isolated Voltage Sensor

Posted on Jan 6, 2013

A simple voltage-controlled oscillator (VCO), coupled to your instrumentation by an optoisolator, allows you to mea

Isolated Voltage Sensor
Click here to download the full size of the above Circuit.

sure high voltages. The component values suit a 0- to 600-V input range (power dissipation in RI and R2 set a limit on the input-voltage range). The circuit"s linearity is not an issue, because you can linearize its output in software. The input voltage (V), charges capacitor CI until zener diode D1 conducts. Then, the zener diode triggers an "avalanche" circuit that discharges CI into optocoupler Ql. After CI discharges, the charging cycle repeats. CI also averages the sensed-voltage level, which thereby provides noise immunity. The optocoupler"s output is a pulse train whose frequency increases with increasing input voltage. To develop a linearizing equation for the circuit, measure its output at two convenient, widely spaced input voltages. Then plug the resulting periods into this second-order polynomial approximation and solve the two simultaneous equations for the two constants, k1 and k2: Vz is the zener voltage of D1.

Leave Comment

characters left:

New Circuits



Popular Circuits

4046 PLL bassed A roulette wheel electronic circuit with explanation
Audio Metal Detector Schematic
sine to square triangle wave
how to make automatic vehicle headlight
broadband rf power amplifier 18 30 mhz
Simple preamplifier circuits by transistors
up down led sequencer
Oscillator Control & GPS