Continuity Checker


Posted on Jan 8, 2013

Ul is an op amp used as a comparator. When the test probes are shorted together, resistors R1 and R2 bias the noninverti


Continuity Checker
Click here to download the full size of the above Circuit.

ng input to half the supply voltage. The inverting input is biased by a voltage divider that consists of R3, R7, and R4. Resistor R7 is adjusted so that the voltage to the inverting input is lower than that to the noninverting input when the probes are shorted together. With continuity across the probes, Ul"s output goes high and supplies power to Ql, which is configured as a relaxation oscillator. The output of Ql is fed to a high-impedance loudspeaker for an audio tone. When the probe is open, the noninverting input goes to the negative supply rail via R2. This action forces Ul"s output low, which results in no output from the oscillator.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Electrolytic Tester
Simple Temperature Indicator
Transistor current limit circuit power handling
digital speedometer circuit schematic
tesla circuit
Metal Detector Circuit
Tube Tune-A-Lite ID37856
Servoelectric Guitar Project
A Christmas lights circuit



Top