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Transistors

Simple 150 Watt Amplifier Circuit using Transistors

Last Updated on May 15, 2026 by Swagatam 81 Comments

amp 1

This 150 watt amplifier is designed to provide a full 150 watt peak to peak music power amplification over a 4 ohm loudspeaker. In this post I have explained how to make a simple 150 watt power amplifier circuit using a typical OCL design which ensures cheap layout and use of minimum components, with high […]

Filed Under: Audio and Amplifier Projects Tagged With: 150, Amplifier, Simple, Transistors, Watt

Battery Full Charge Indicator Circuit using Two Transistors

Last Updated on May 17, 2026 by Swagatam 104 Comments

Highbatteryindicatorcircuit

This little circuit will alert the user regarding a battery reaching its full-charge level (over charge) while it’s being charged, by illuminating an LED. The circuit uses just a couple of transistors as the main active components. Main Feature The main feature of this design is not only its mini design but also its supply […]

Filed Under: Battery Charger Circuits Tagged With: Battery, Charge, Full, Indicator, Transistors

How PNP Transistors Work

Last Updated on May 20, 2026 by Swagatam 8 Comments

pnptransistor

In this post I have explained regarding how a PNP transistor works or conducts in response to a fixed biasing voltage and a varying supply voltage, across its base and emitter. The question was put forth by Mr. Aaron Keenan. Question Regarding PNP BJT Working Great information and lots of interesting circuits!I have a question […]

Filed Under: Electronics Theory Tagged With: PNP, Transistors, Work

Sequential Timer Circuit using Transistors

Last Updated on June 1, 2026 by Swagatam 23 Comments

sequence2Bgeneartor

In this post I have explained to make a simple sequential timer generator circuit which can be used for getting a sequential triggering of a connected load, or can be simply used like a sequential LED bar graph effect generator, using only transistors. The idea was requested by Mr Babusan.  Technical Specifications Is it possible […]

Filed Under: Lamps and Lights Tagged With: Sequential, Timer, Transistors

Simple Thermostat Circuit Using Transistors

Last Updated on January 2, 2024 by Swagatam 29 Comments

simplethermostatcircuit

The electronic thermostat explained here can be used to control the room temperature by appropriately switching (turning on and off) a heating device. By: R.K. Singh Operational details of electronic thermostat The circuit employs a thermistor NTC (negative temperature coefficient) as the sensor device. – As long as the ambient temperature stays higher than the […]

Filed Under: Temperature Controllers Tagged With: Simple, Thermostat, Transistors

Low Battery Indicator Circuit Using Two Transistors Only

Last Updated on August 3, 2026 by Swagatam 211 Comments

lowbatteryindicatorcircuit 2

In the following post I have explained a simple low battery indicator circuit by using just two inexpensive NPN transistors. The main feature of this circuit is its very low stand by current consumption. The Circuit Concept We have so far seen how to make a low battery indicator circuits using a 741 IC and […]

Filed Under: Battery Charger Circuits Tagged With: Battery, Indicator, Only, Transistors

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