What got me interested in building these diminutive devices is the S3FM connector assembly made by Switchcraft. The S3FM is simply a 3.5-inch tube fitted with a male XLR at one end and a female at the other, with enough room in the middle to build a mike....

This Power amplifier is equiped with a bipolar transistor,the famous MRF317. As lots of FM amplifier application ,the power transistor is in a C class bias. All the impedance networks (Input & Output) have been determined by using the software: Mimp.EXE. A 9....

Many times we needed a stabilized, together regulated power supply and high relatively output voltage. These specifications him it cover our circuit. It `s a circuit that can give in his exit + 40V until + 60V 3A, with simultaneous stabilization. The....

The amplifier in Figure 1 originally served as the photomultiplier preamplifier in a Doppler system intended for eventual operation in the Martian atmosphere. The design is based on a switchable array of six Maxim MAX4258 dual-channel video....

This simple circuit generates narrow pulses at about 700-800Hz frequency. The pulses, containing harmonics up to the MHz region, can be injected into audio or radio-frequency stages of amplifiers, receivers and the like for testing purposes. A high-pitched....

You'll find that this is a very easy project to build. It will transmit good quality sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on 3 volts DC. The chip will get destroyed if it is operated on any voltage higher....

A simple but useful circuit for all they have problem with parking car, in spaces without good visibility. The electric circuit appears in picture 1. It is constituted by the IC1 and components round he. When the car bumper touch soft and push lightly the....

Electromechanical door chimes can enhance your home, but they are vulnerable to costly repair problems. A defective pushbutton switch or a careless visitor can maintain the chime in an energized state for a prolonged period, thereby damaging the chime. The....

Take care with transmitter circuits. It is illegal in most countries to operate radio transmitters without a license. Although only low power this circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres...

This circuit provides 16 watts of amplification. it is built using two LM383 power audio amplifiers. use suitable heat sinks with the ic`s...

The transmitter runs on only 3V whereas most others run on more voltage. This dirt cheap item uses non-adjustable inductors so it is not possible to tweak for higher output. The common TX2B chip is manufactured by HIGHLAND (SHENZHEN) ELECTRONICS CO LTD and....

In recent years, following CD`s introduction, vinyl recordings are almost disappeared. Nevertheless, a phone preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap....

This self-build project can simulate a telephone call / connection between any two local telephone devices. This for a fraction of the outlay of some commercial units, many with cost-increasing features that usually are not required. The circuit is centred....

For the 60W amplifier, a nominal (full load) supply of +/- 35V is required, so a 25-0-25 secondary is ideal - however, see Updates, below. The circuit for the supply is shown below, and uses separate rectifiers, capacitors and fuses for each channel. Only....

It is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery. You can add a 6.2V zener diode and a LED to warn you when the input supply is overvoltage. If you could find a relay that would operate from 6.2v right up to....

In its simplest form, a voice-over unit is just a microphone and change-over switch feeding an amplifier, the output from the microphone having priority over the amplifiers audio signal when the "push-to-talk" switch is pressed. In this circuit, a....

This mini audio amplifier will test the audio stages in amplifiers such as the front end of FM bugs. You can also use it on lots of our other projects as well as the output stages of radios. It is a very handy piece of test equipment and will make a perfect....

This circuit is designed primarily for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on, the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the....

In an R-2R DAC design with supply voltages exceeding ±5V, large voltage glitches (up to 1.5V) can occur during the DAC`s major-carry transitions. These glitches can propagate through the output buffer amplifier and appear at output. The slewing of the level....

The IRF820 MOSFET has a voltage rating of 500v, it should work well in preamp stages of most tube amps. The 100 ohm resistor is there to suppress H.F. oscillations. If IRF820 is physically close to the 12AX7 plate, you probably won't need it. You can see how....

Recently, I have needed to measure inductances in the hundreds of microhenries to several millihenry range. Though I have a pretty good LRC meter and an excellent bridge on my workbench in Mesa, Arizona, I wanted to make these measurements in my home in....

The whole Construction : You can call the transceiver like this as "OZL type". Characteristics of the "OZL type" are as follows. 1. Single conversion super. 2. Using two DBM-s as modulator and converter. 3. Modulator DBM is used as demodulator in....

A special category of preamplifiers, they are the preamplifiers that undertake they amplification the low exit of Moving coil head, so that its drive to a input PHONO [RIAA] of preamplifier. With the moving coil heads, exist certain problems which it should....

Many modern audio recorders is now compatible with digital input S / PDIF (Sony / Philips Digital Interface). Devices like CD Changers, MiniDisc recorders, computer sound cards and the like. working with digital signal just with protocol S / PDIF. Digital....

Basically, this is a frequency-current converter. It is used as frequency meter. Calibrating it can be used as tachometer. Please be aware this is an experimental project, I didn't use it connected on any vehicle but it should work fine after calibration. It....

When you need a precision peak detector, you would usually implement it with one or several op amps and a few other associated components. This technique usually works well unless your design requires operation higher than a few kilohertz. In designs....

The generators of square pulses, are used in a lot of applications, between which the adjustment of conditions of entry in the digital circuits and the control of amplifiers acoustic frequencies. This circuit is a generator that it produces, in combination....

A number of single-chip VGAs variable-gain amplifiers are available today. Unfortunately, they all have drawbacks, such as high noise, 55V limit, low input impedance, or nonlinear gain/frequency characteristics. The circuit in Figure 1 is a 16-step,....

This is a very useful circuit for those who want to transform a stereo Power Amplifier, to mono, bridging two channels from him , reversing the phase of the one power amplifier [R] and the polarity, with these connections we can have 4X times the output....

Many designers opinionate that NFB loop controlled amplifiers are inferior because they degrade the sound, and yet I wonder what it is that these individuals think they actually listen to ? The fact is that most vinyl waveforms and CD pits, as pressed into....