This last article on bipolar junction transistors (BJT) is a potpourri of circuits. Some are practical and some are not so practical, but they can be great for experiments. With these circuits you can amplify signals, filter high and low frequencies,....

The circuit even has a current limiting feature which is a more reliable system than most commercial units have. The circuit uses 3 pass transistors which must be heat sink. Resistor R9 allows the fine tuning of the voltage to exactly 13. 8 volts and the....

Here is a simple but inexpensive inverter for using a small soldering iron (25W, 35W, etc) In the absence of mains supply. It uses eight transistors and a few resistors and capacitors. Transistors Q1 and Q2 (each BC547) form an astable multivibrator that....

The ability amp lath has remained banausic back it was aboriginal appear in 2002. It absolutely isn`t broken, so there`s no acumen to fix it. The photo beneath shows a absolutely accumulated lath (available as apparent as M27). Application TIP35/36C....

This 2 channels audio mixer is based on the 2n3904 transistors which forms 2 preamplifiers. The first preamplifier of the audio mixer has a high gain and can be used for microphone input, and the second one can be used to control the input of the audio....

Experiments with couple of floppy drives I have and it appears that on the step pin, current is limited to around 5 mA. This means that we can indeed omit the collector resistor in this case. For base, I`d recommend a 1 kiloohm resistor. This will give us 3.....

A low ripple regulated DC power supply designed based on transistors is shown here. Such transistor voltage regulators are suitable for application where high output current is required. Conventional integrated series regulators like 7805 can only deliver up....

The circuit of this device is quite simple: an input circuit filters the signal provided by the antenna to reduce sensibility to other phenomena and protects against over voltages. The four transistors realize a "one-shot" section that is triggered by the....

This device is designed to be a simple, inexpensive comparator`, intended for use in a solar cell power supply setup where a quick too low` or just right` voltage indicator is needed. The circuit consists only of one 5V regulator, two transistors, two LEDs,....

This simple dual digital dice is based on three low-cost ICs, a few transistors and a handful of LEDs. IC1a & IC1b operate as an oscillator with a frequen....

A very simple FM transmitter circuit can be designed using MC2833 integrated circuit, designed for cordless telephone and FM communication equipment. It includes a microphone amplifier, voltage controlled oscillator and two auxiliary transistors. The final....

Flip-flop, as an astable multivibrator, can be used to generate timing signal in music: metronome. By adjusting transistor bias resistor using a 100k....

A ringer interface circuit, and I`m running into problems that are over my head. The purpose of the circuit is to buffer the output of a central telephone system that goes to several ringers spaced throughout the building. The reason for the circuit is that....

An H bridge is a kind of circuit you use to control the direction (and sometimes speed) of an electric motor, using only a single polarity voltage (you need to reverse the way current flows in order to reverse the way the motor rolls). You have 4....

LDR( Light dependent resistor ) Engineering is a technique of making several electronics circuits following thelogic of a simple light and dark sensor using transistors, 555 IC and 741 IC. Out of several optical sensors, light dependent resistor can beused....

This circuit will flash a bright or high-brightness red LED (5000 mcd). Great for fake car alarm or other awareness getting equipment. Component values aren`t significant, attempt anything else first from the junkbox. Obviously, the 470 ohm resistor (R3)....

This amplifier designed for TV transposers and transmitters, it incorporates microstrip technology and discrete linear push-pull transistors with gold metalization and diffused emitter ballast resistors to enhance ruggedness and reliability. Fully assembled....

This circuit is an astable multivibrator, or oscillator. The two transistors are cross-coupled in such a way that the circuit switches back and forth between two states. In one state, the base of Q1 is about one diode drop above ground, allowing a base....

Here is a simple head phone amplifier circuit that can be used to drive your head phone if your music player doesn`t have enough power to drive your head phones. The circuit is straight forward and uses only three transistors. The transistor Q1 (BC 239) and....

The drawing below illustrates a multistage light sequencer using descrete parts and no integrated circuits. The idea is not new and I hear a similar circuit was developed about 40 years ago using germanium transistors. The idea is to connect the lights so....

A very simple water level controller circuit based on 555 IC and 6 transistors. A relay is used for switching the pump motor....

This circuit is a small digital ?roulette``. It is constituted by oscillator IC1, the counter IC2, the transistors Q1-7 that drive the display common cathode DSP1. The supply basically becomes from a battery 9V, but can become also from one power supply....

What about the 10K resistors at the bases of the transistors, and the 1K resistors at the collectors. Keep those with theTransistors when I move them, orget rid of them If the 10K resistors are not included the transistors will blow-off, without the 1K....

All types of transistors including Darlington and power will be tested in this project. Connect the 9v battery around the other way at points A and B to test....

Electronics Tutorial about Light Sensor including Photocells, LDR, Photodiodes, Phototransistors, Photovoltaic Cells and Light Dependent Resistor....

Here is a simple but inexpensive inverter for a small soldering iron (25W, 35W, etc) In the absence of mains supply. It uses eight transistors and a few resistors and capacitors. Transistors Q1 and Q2 (each BC547) form an astable multivibrator that produces....

This rain detector electronic circuit project is an very simple alarm circuit, that will start an audio warning, if the liquid is present on the sense pad. This rain detector electronic circuit diagram is based on two transistors. When the sense pads....

The HandyBoard drives both pads at the positive supply of the battery. When one of the motor is supposed to turn, the handyboard drives the appropriate pin at 0V. The difference between two pads makes the motor turn. The Transistors are TIP 120 and TIP 125....

A very good 1 watt fm transmitter circuit, very easy to build circuit. It has 4 transistors, one is a very stable oscillator, followed by a buffer stage to prevent frequency variation when you adjust the transmitter. Next is a resonance stage and the final....

This is a Mini MW (Medium Wave) Transmitter circuit. This circuit consist of combination of transistors SA103 and SA101. Those transistors is used as oscillator...

Flight Computer V1. 0: B1 PC Board U1 80C32 microprocessor U2 27C256-12 32Kx8 ROM - 120nS "V2. 1" U3 74HC373 U4 LM340T-5 5v regulator (might be a 7805 part) U5 43256-15 32Kx8 RAM - 150nS U6 74HC00 T1-T4 2N6045 or 2N6044 darlington output transistors Y1 11MHz....

This PLL transmitter is controlled and the frequency is very stable and can be programmed digitally. Transmitter will work 88-108 MHz and output power up to 500mW. With a small change can set the frequency of 50-150 MHz. The output power is often set to....