Audio Circuits

Two transistor tone controller

Description. Here is the circuit diagram of a simple two transistor tone controller circuit. This circuit is based on the famous Baxandal tone control design. The transistor Q1 is wired an emitter follower to provide sufficient current gain and input impedance. The second transistor is used to voltage amplify the signal in. The network of […]

Equipment Reviews

Equus 3320 Auto-Ranging Digital Multimeter

Every electronic maniac needs a Multimeter, which’s his basic tool. From the plenty of multimeters available in the market, how to choose the BEST one? I thought of reccomending the one I use for my readers. I have been using Equus 3320 Auto-Ranging Digital Multimeter for a year or so and I must say I

101-Announcements

We are now on Twitter

Hai readers, We are now present at Twitter-The latest internet sensation. You can now follow us on Twitter to get the latest updates from our blog-CircuitsToday.com Follow Us On Twitter Now: (Click the image below) Best Regards, Social Media Team, CircuitsToday.com

Audio Circuits

2X15 Watt stereo amplifier using TDA4935

Description. TDA4935 is bipolar stereo amplifier IC that can be wired as a 2X15W stereo amplifier or a 30W mono BTL amplifier. The IC also features built in circuitry for over load protection and over temperature shut down. Here the IC is wired in stereo mode in order to deliver 15W power on each speaker.

Electronics Books

Practical Electronics for Inventors

Today I have gone through a book Practical Electronics for Inventors written by Paul Scherz, which describes the various practical circuit ideas and designing techniques.Its 585 page big book with all basic ideas related to electronics. I am reviewing and recommending this book here,because I am getting tons of comments from newbies in electronics asking

Radio Circuits

Single transistor radio

Description. Here is the circuit diagram of a simple radio that uses one transistor and few other passive components.The C6 and L1 forms a tank circuit which picks up the signal from your desired radio station.Diode D1, capacitor C2 and resistor R1 does the detection of the picked signal.The detected signal is coupled to the

Battery Circuits

Flashing battery monitor

Description. Here is a simple circuit in which an LED will continue flashing as long as the voltage of the battery to be monitored is above the set level.The transistors Q1 and Q2 are wired as a complementary astable multivibrator.The circuit can operate from a voltage range from 6V to 12V. The voltage level at

Lighting Circuits, Power Supplies

Delayed ON LED

Description. Here is very simple circuit in which the LED becomes ON only after a preset time the power supply is switched ON. When the power supply is switched on the transistor will be OFF. The capacitor now charges via the preset R3 and when the voltage across C1 is sufficient, the transistor switches ON

Radio Circuits

AM receiver circuit

Description. Here is a low cost AM receiver circuit that can be tuned from around 550 to 1100 KHz. Three transistors are used in this project. The transistors Q1 and Q2 are wired as a compound transistor pair in which Q1 is an emitter follower and Q2 is a common emitter amplifier. The emitter follower

Audio Circuits

Stereo line driver circuit

Description. This is the circuit diagram of a low cost stereo line driver is given here. The circuit consists of only two transistors and few passive components. Each BC 109C transistor is wired as an emitter follower for driving each channel. The voltage gain of the emitter follower is unity, but it has a high

Battery Circuits, Lighting Circuits

Battery operated mini night lamp

Description. This is the circuit of a low power LED night lamp that will automatically switch OFF at day time. The CMOS timer IC TS555CN is wired as a square wave generator operating at around 5Hz.The output voltage from the IC1 is doubled using the combination of capacitor C2 and diode D2 in order to

Audio Circuits, Transmitters

Audio monitoring system

Description. Here is the circuit schematic of a simple audio surveillance system in which the transmitter will pickup sound from one location and the receiver at other location will reproduce it. The receiver and transmitter are connected by only one set of wire. Here both power supply and transmitted signal share the same wire. The

Radio Transmitters

Medium power FM transmitter circuit

We have opened an online store where 4 very good books on basic electronics are kept for sale. You can read the detailed reviews and authors profiles and buy the book. Books from renowned authors like Forrest M Mims, Charles Platt, Harry Kybett, and Earl Boysen are included. Check it out here:- 4 GREAT BOOKS TO

Automotive Circuits, Battery Circuits

3 LED battery monitor circuit

Are you not familiar with the basics of electronics? We have just opened an online store where 4 very good books on basic electronics have been kept for sale. You can read the reviews of these books and buy them as you wish. These books are being followed by students in some of the best

Test & Measurement Circuits

Quartz crystal tester circuit

Description. This a very simple and inexpensive circuit that can be used to test quartz crystals.Here a Colpitts oscillator is wired used the transistor T1.When the crystal is connected between terminals A and B the circuit will produce high frequency oscillation.The oscillations will be generated only if the crystal is a good one.The diode OA91

Power Supplies

5V power supply with overvoltage protection.

Description. For circuits using TTL ICs the supply voltage is a great concern and a slight increase in supply from the rated 5V may damage the IC. Using fuses alone does not solve the problem because a fuse may take several milliseconds to blow off and that’s enough time for the IC to get damaged.

Power Supplies

Adjustable regulator using L200

Description. Here is the circuit diagram of an adjustable voltage regulator using IC L200. L200 is a monolithic integrated adjustable voltage regulator IC having features like current limiting, thermal shut down, power limiting, input over voltage protection etc. Here the regulator is designed to produce an output adjustable between 2.85V to 15V at 1A.The resistors

Power Supplies

Blown fuse indicator circuit

Description. Here is a simple scheme for adding a blown fuse indicator to your existing power supply circuit. This is done by just adding a resistor and LED to the existing circuit. The LED and resistor are connected in series and this combination is connected in parallel to the existing fuse. When the fuse is

Fun & Game Circuits, Tone generator circuits

Canary chirp generator

Description. This is a simple electronic alarm circuit that imitates the chirping of a canary. The circuit is nothing but a Hartley oscillator with few more passive components added. As the capacitor C1 charges through the resistor R1 and the transistor Q1 is driven to cut off. This makes the oscillations to stop. As the

Audio Circuits

3 Band graphic equalizer circuit

Description. Here is the circuit diagram of a simple 3 band graphic equalizer circuit using a single IC and few components. The IC used here is LF 351 which is a wide bandwidth single JFET operational amplifier. The high input impedance of the IC makes this circuit compatible with most of the audio signal sources.

Sensor Circuits

Electromagnetic field sensor circuit

Notes. This is a very simple circuit that can be used to sense electromagnetic radiations. The circuit can even detect hidden wrings. A 1mH inductor is used for sensing the electric field. The electric field will induce a small voltage in the sensor inductor and this induced voltage is amplified by the opamp.The headphone connect

Audio Circuits, Conversion Circuits

Speaker to microphone converter circuit

Description. This circuit is a simple approach for converting a loud speaker into a microphone. When the sound waves fall on the diaphragm of a speaker, there will be fluctuations in the coil and there will be a small proportional induced voltage. Usually this induced voltage is very low in magnitude and useless. Here in

Audio Circuits, Transmitters

Simple IR audio link

Description. Here is a simple IR audio link that can be used to transmit audio signals up to 4 meters. The signal to be transmitted is applied to the base of Q1 via resistor R4.The transistor Q1 drives the IR transmitting diodes D1 and D2.The audio input will be modulated to the IR signals transmitted.

Lighting Circuits

4W Fluorescent lamp driver.

Description. This is a simple 4 W fluorescent lamp driver circuit that can be operated from a 12 V supply.The first part of the circuit includes a NE555 timer IC wired as an astable multivibrator.The output pulses from the IC are amplified by the transistor Q1.The transformer steps up the collector voltage to around 1KVto

Scroll to Top