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Tester

DIY Contactless HT Spark Tester & LED Timing Light Circuit for Modern Cars

Last Updated on October 6, 2026 by Swagatam 2 Comments

Today I am going to share a very useful and clever circuit diagram sent to me by Mr. August Peterson. This circuit is a non-contact HT spark tester and timing light tool. It is specially designed for modern cars where checking for a spark is very difficult and dangerous for the car electronics. Why Mr. […]

Filed Under: Automobile Electronics Tagged With: Contactless, DIY, HT, LED, spark, Tester

Accurate Transistor Tester Circuits Explored

Last Updated on June 8, 2026 by Swagatam 12 Comments

transistor tester circuit diagram

In this article we talk about a few simple yet accurate transistor tester circuits which can used to identify whether a transistor is good or bad. Note: Please test *only* BJTs and MOSFETs (enhancement or depletion) with these circuits. Simple Good/Bad Transistor Checker using a Single LED Do you have a lot of strange old transistors […]

Filed Under: Meters and Testers Tagged With: Accurate, Circuits, Explored, Tester, Transistor

Simple LED Forward Voltage Drop Tester Circuit

Last Updated on August 10, 2026 by Swagatam Leave a Comment

amber LED testing

Semiconductor LEDs (Light Emitting Diodes) produce light when current flows through them. In comparison to conventional lighting sources, LEDs offer a number of benefits, including high energy efficiency, extended longevity, and low thermal output. The forward voltage drop of an LED is one of the important factors that affects how well leds performs. We will […]

Filed Under: Meters and Testers Tagged With: Drop, Forward, LED, Simple, Tester, Voltage

Semiconductor Tester Circuit [LED, Transistor, SCR Tester]

Last Updated on June 8, 2026 by Swagatam 2 Comments

LED diode transistor SCR tester circuit

The semiconductor tester circuit I have explained below performs continuity tests on SCRs, bipolar transistors, and diodes. How the Circuit Works A squarewave oscillator with a frequency of about 350 Hz is produced by a couple of IC 4049 gates, U1a along with U1b, R1, R2, and C1. The complementary outputs required for testing both NPN and […]

Filed Under: Meters and Testers Tagged With: LED, SCR, Semiconductor, Tester, Transistor

Simple IC Tester Circuit [Test Digital and Analogue ICs]

Last Updated on June 8, 2026 by Swagatam 3 Comments

Cable with banana pins and micro alligator clips

The IC Tester is simple to use. You don’t have any  switches to configure or lengthy test processes to complete. The universal IC Tester is a static tester, which means this does not dynamically test the IC’s operation. All ICs with up to 20 pins can be tested by this unit. ICs  with more than […]

Filed Under: Meters and Testers Tagged With: Analogue, Digital, Simple, Test, Tester

Simple Crystal Tester Circuit

Last Updated on June 8, 2026 by Swagatam 15 Comments

crystal tester compressed

In this post I have explained how to build a simple crystal tester circuit using ordinary parts like transistors, resistors, diodes and capacitors. What is a Crystal A crystal can be used for making an electronic oscillator circuit by using the mechanical resonance of a piezoelectric vibrating crystal to generate an electrical frequency having a […]

Filed Under: Meters and Testers Tagged With: Crystal, Simple, Tester

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