Voltage Test Probe


Posted on Oct 3, 2012

Using inexpensive components, you can fit a simple probe circuit into a pencil-sized enclosure. When both LEDs are on, the probe indicates the presence of an ac voltage; either LED alone indicates the presence and polarity of a dc voltage. The diode-bridge arrangement allows one-way current source R1, R2, Q1, and Q2 to light either LED (or both) when the probe is activated by a test voltage.


Voltage Test Probe
Click here to download the full size of the above Circuit.

Diodes provide the necessary peak-inverse voltage rating; R3 and C1 provide a spike-suppression network to protect the current-source transistors.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

PIC16F628 as digital Tachometer
Simple Pulse Generator
90-125 Mhz Crystal RF Oscillator
Ultimate Continuity Tester Hides Many Tricks Up Its Sleeve
555 timer touch activated alarm circuit
chip programmer
80 mhz 108 mhz fm transmitter circuit
Cuckoo sound Generators



Top