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 […]
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Blinking LED Circuit using LDR and Resistors
This is perhaps the most simplest looking LED flasher that does not depend on any semiconductor. This LED blinker circuit utilizes ordinary passive components like a few resistors, a capacitor and an LDR. Meaning, this LED flasher does not depend on transistors or ICs to create the blinking effect. Circuit Description The LED-LDR combination is […]
Light Emitting Diodes (LED) Explained
The full form of LED is Light Emitting Diode. LEDs are special type of semiconductor diodes which emit light in response to a potential difference applied across their terminals, hence the name light emitting diode. Just like a normal diode LEDs also have two terminals with polarity, namely anode and cathode. To illuminate an LED […]
Light Meter Circuit with LED Bar Graph
In this article I have explained 3 different light meter circuits for measuring power of light. In the first method we will use only a solar cell and a multimeter, in the second method we will use an op amp and a moving coil meter, and in the third method we will see how a […]
Temperature Controlled Relay Switch Circuit
In this article I have explained a simple temperature controlled relay circuit which can be switched ON/OFF depending on the temperature on its temperature sensor. Meaning, when the temperature on its temperature sensor rises above a set threshold point, the relay switches ON, and when the temperature drops below the threshold, the relay switches OFF. […]
LED Oscilloscope Circuit
The simple LED oscilloscope circuit I have explained in this article can be used for analyzing low frequency waveform through a 10 x 10 LED matrix display. Due to the involvement of only 100 LEDs in the display board, the resolution is low, and the waveform display clarity is not so impressive. Yet, this LED […]