These photos were made in the years 1956 and 1957. On photo nr. 3, on the right, at the bottom, is the GMD. The work that was done at the objekt was of course top secret. It was strictly forbidden to talk to any acquaintance or relative about the work.....

This design for a headphone amplifier arose after the purchase of commercial equipment with separate pre and power amplifiers without a headphone output. Its advantages are ... * low output impedance to drive several pairs of phones * the active....

My FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike. It has been used inside guitars and as the basis of a remote control system. I do however, receive many requests for a higher powered circuit and....

The preamp featured is very straightforward to make on the PCB, and has an innovative tone defeat function. Rather than completely disable the tone controls, they are massively de-sensitised, and when "defeated" have a maximum range as shown in Fig. 3....

The GHF1 is a small generator covering the HF and LF band from 30 Hz to 30 MHz in 6 ranges. The sinusoidal signal obtained can be amplitude modulated (AM) or frequency (FM). The GHF1 also has a sweep function. An LCD display 2 x 16 characters allows the....

The peak output voltage will be approximately 15,000 to 20,000 volts, but this will vary with the ignition coil type and the voltage at which the MOV starts conducting. Do not touch any part of the 555 circuit including any leads of the timing resistors or....

The Thermistor, or NTC (Negative Temperature Coefficient) of 10K, is a standard type. Most types will work. The one in the diagram is a 10K model made by Fenwal (#197-103LAG-A01). The resistance lowers as the surrounding temperature increases which affects....

Hot wire foam cutters are used by hobbyists of all stripes to contour Styrofoam into a vast array of shapes for a wide variety of uses. Model railroad builders shape foam into landscapes. RC plane builders shape foam into aircraft wings and fuselages.....

It can safely charge a 7-cell RC2000 pack in about 14 minutes, and an RC2400 or CP2400SCR pack in about 17 minutes. As a NiCd cell is being charged, two things happen which affect its temperature. Due to resistive losses within the cell, some of the charging....

We are OUT OF STOCK on the surplus brushless DC motor we used to build this project, and since it`s surplus we cannot get any more. The resistor and capacitor values listed in the schematic and on the PC board plan depend on using this exact same motor...

Class-A is ideal for this application, since headphones are such an intimate way of listening. An amplifier for 'phones should be as clean and free from crossover distortion as possible, and must also be quiet. A background of hiss and hum does nothing to....

A Hartley oscillator is shown at the right. It uses most of the same components as the Clapp oscillator. A capacitor is necessary to block the gate bias voltage from the tuned circuit. The tuning capacitor is a 100 pF poly capacitor. L1 is a coil wound with....

The amplifier operates primarily in the current domain. The first stage is a voltage controlled current sink. The second stage is a current-controlled voltage source. The fourth stage is a constant current sink. The main advantage of current domain....

Examine a traditional Hartley oscillator circuit, and you`ll note its trademark: a tapped inductor that determines the frequency of oscillation and provides oscillation-sustaining feedback. Although you can easily calculate the total inductance required for....

This unit is designed to interface: TV sound, videotape sound, and 5.1 dvd sound to a 4 channel home theater system. It provides the following functions/options. Mix DVD center into front left/right for Phantom Center effect with optional boost on center....

This simple amplifier is ideal for adding a headphone jack to equipment that lacks this feature. The Headphone Buffer circuit board is small enough (1.2" X 1.4") to squeeze into even the smallest spaces and power requirements are so low that existing....

Input Amplifier Module: a low noise circuit equipped with a variable voltage-gain (10 - 100) pre-set, primarily intended as high quality microphone input, also suitable for low-level line input. High-quality modular design. 9V Battery powered - Very low....

Ham Radio (amateur radio) is a popular hobby amongst electronics enthusiasts all over the world. Basically the hobby involves a person in making his own gear consisting of a receiver and transmitter or a transceiver (a receiver and a transmitter in one unit)....

This article discusses several opamp-based headphone amplifier circuits, including suggestions for selecting opamps, input coupling and filtering, high current output stages and power supply options. There are no recommendations for specific opamp brands or....

These pages describe my project to build simpler and less expensive amateur seismometers by using microprocessors and other new chips, such as switched capacitor filters. I have tried to provide links to much of the excellent information that is already on....

High Quality unit with LM833 or NE5532 Low noise Dual Op-amp. No need for a preamplifier. # Can be directly connected to CD players, tuners and tape recorders. # Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000....

There is enough of poorly constructed RS232 alike TTL level interfaces (+5volt) , this one generates it`s own +/- 10..11volts as RS232 specs. require , and is able to use very long cables like RS232 can , and protects computer as well , nice in funny....

A LED is defined as "light-emitting diode: diode such that light emitted at a p-n junction is proportional to the bias current; color depends on the material used" [Princeton University]. As the LED is a diode, it doesn't conduct electricity in both ways and....

Save fuel bills and the economy of the planet with this circuit. SW1 is a normally open press button switch which allows you to view the level of hot water in a hot water tank. When pressed the voltage difference at the junction of the thermistor and preset....

For those who dont like microcontroller projects, pretend the micro is a dedicated LED driver IC that just happens to have been designed to control 30 LEDs in the shape of a Heart (what a stroke of luck!). And it wont be declared obsolete just after....

the AD844 was still used, but this time the feedback loop went all the way from output and back to input. The DC servo was removed and the current source was made faster, using an extra transistor. The local feedback was turned into global feedback, lowering....

An amplifier to drive low to medium impedance headphones built using discrete components. Both halves of the circuit are identical. Both inputs have a dc path to ground via the input 47k control which should be a dual log type potentiometer. The balance....

The simplest technique for measuring current in an actuator or a motor is to monitor the ground current with a resistive element between the load and the ground. Because the device and its associated electronics share a ground potential, you need to amplify....

A crucial point in the design is the input/decoder section, and the question of what ICs to use for decoding the input video to component digital video streams. The choice for this project was the Philips IC SAA7114H, new on the market at the time. This chip....

This page features H-Bridge circuits used for controlling direct current motors. Several designs are shown using both CMOS and Bi-Polar power devices. These circuits could be used as the basis for Model Railroad DCC Boosters or PWM motor controllers. The....

This preamplifier is requirement result of many friends to give a high quality preamplifier, capable to drive high quality power amplifiers with good sound, it`s not however difficult to making, it combines simplicity and handiness. It does not allocate a....

This Design Idea presents a simplified ac high-voltage amplifier that uses complementary, cascaded NMOS and PMOS transistors (Figure 1). The OP07 op amp has low input-offset voltage, low input-bias current, and high open-loop gain...