under?-over voltage detector


Posted on Jun 17, 2012

In Fig.1 A precision DC under?voltage relay switch. The opamp is wind as a voltage comparator, with a reference voltage applied to pin 2 and the test voltage applied to pin 3: the relay turns on when the pin 3 voltage exceeds that of pin 2. The circuit can be made to trip at any voltage in excess of 5 volts by suitable choice of R1 value. In Fig. 2 An over-voltage switch that can be used to trip at any pre-set voltage in excess of about 10 mV. The input voltage can be connected directly to pin 2 if trip values in the range 10mV to 3Volts are required. For voltages in excess of 3 Volts, a suitable range resistor must be connected in the position shown, to keep the pin 2 Voltage drive to suitable level. The circuit can be converted to an under?voltage switch by transposing the pin 2 and pin 3 connections of the op-amp.


under?-over voltage detector
Click here to download the full size of the above Circuit.

The circuit can be used as an AC voltage switch by first rectifying the AC input signal. Part List R1=2Kohm/V minus 10Kohm R6-11=2.2Kohm D3-5=1N4001 R2-9-10=1Kohm R7-12=4.7Kohm D4=3V3 0.5W Zener R3-8=10Kohm RV1-2=10Kohm pot. IC1-2=LM741 R4=1.2Kohm D1=6V8 0.5W Zener Q1-2=BC214 R5=47Kohm D2=5V6 0.5W Zener RL1-2=12V >120ohm Relay




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Simple Digital Potentiometer with DS1869
Tubes Headphone Amplifier
High q notch filter
12V to 9 or 6 v converter
-15-V-1-a-regulated-power-supply
sn754410
CVS Oral Thermometer Dissection
Easy 5V 10A switching regulator by L4970A
Armstrong Oscillator
Creating Fast Line Transients
pll circuit



Top