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Thursday, 30 November 2023

How to Design Schematic Circuit of Universal Probe

 This ultra-simple probe can be used to test almost every electronic component. CapaCitOrS, reSiStorS, fuses, SwitcheS, COils, tranSformerS, diOdes, wires,

etc., can be tested with this simple circuit.

Only three components are used and they can easily be housed in a small

plastic box, performing as a portable unit.

The circuit consists basically of a continuity tester with a visual indication by

an LED. lf current can flow between the probes the LED glows; if not, the LED

remains otf.

Current flowing between probes is very low to avoid overloading the tested

components.

A schematic diagram of the Universal Probe is shown in Figure 1. As you can

see, only three electronic components are used in this project.

A components layout view is shown in Figure 2.The components can be

housed in a small box and no ON-OFF sutitch is necessary.

When mounting, take care with position of the two polarized components" the

LED and power supply.

The power supply conslsts of two M cells.

An ON-OFF switch is not necessary as the circuit is otf when the probes are

separated.

Current through the component under test is determined by the voltage drop

across the LED (about 1.6V for red LEDs and 1.8V for yellow LEDs), and

resistance of R1.




Parts List - Universal Probe

LED - Common red, green or yellow LED

R1 - 470 ohm, 114W,5% resistor

PP1, 2 - Red and black probes

81 - 3V - two AA cells

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