A common need in many systems is to obtain positive and negative supplies from a single battery. Where current requirements are small, the circuit shown is a simple solution. It provides symmetrical +&- output voltages, both equal to one half the input....

By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 ? 99sec stopwatch to a 0 ? 60sec stopwatch. We must find a way to control the RESET function of the BCD counter, which is responsible for the counting of....

The traditional frequency multiplier requires many elements: a phase comparator to detect the phase error between the input and the output signals, a lowpass filter to convert the phase error to a dc control signal, a VCO to generate the output, and a....

The metal detector circuit is shown here that the limits represent the sake of simplicity for a metal detector, but the design works remarkably well. It only uses 40,106 Hex Schmitt inverter IC, a capacitor and a search coil and of course batteries. An....

If the transmitter stick-potentiometer delivers a voltage about 2 - 3 V, this circuit will be suitable. If you want to avoid using the battery cable (supplying Vcc for IC1and -2), you can use a separate 5V supply for IC1 and -2. In that case you should test....

The EAGLE Layout Editor is an easy to use, yet powerful tool for designing printed circuit boards (PCBs). The name EAGLE is an acronym, which stands for: * online Forward- and Back-Annotation * context sensitive help function....

This very simple circuit acts as a high sensitivity capacitive sensor. Lamps and/or Buzzers are operated at half the mains supply voltage when a part of the human body comes in contact with the sensor or approaches it at a close distance. The circuit can be....

Figure 1 presents an alternative to the typical boost power regulator. A buck-converter IC, IC1, generates the higher voltage that the white-light LED needs. An internal buck power stage connects between VIN and PGND, sourcing current to output Pin L. This....

This circuit operates two LED strips in pulsing mode, i.e. one LED strip goes from off state, lights up gradually, then dims gradually, etc. while the other LED strip does the contrary. Each strip can be made up from 2 to 5 LEDs at 9V supply. The two....

This Is a capacitor power supply. This is a very small currents of energy-effective, because it has very little loss, much smaller than the miniature transformer. Capacitor impedance is inversely proportional to frequency. This is a great disadvantage when....

The world is full of xtal oscillators twiddled by digital designers lacking in the analog design knowledge necessary. Just look at all the PC real time clocks that lags or leads by several minutes per day. And they eat backup batteries too! IC`s with pins....

This circuit adds a power down function to analog I/O ports (for example, the AD7769 and AD7774). Moreover, the diodes ordinarily needed to protect the devices against power-supply missequencing can be eliminated Bringing the power down control high....

Osmond PCB is a flexible tool for designing printed circuit boards. It runs on Macintosh. Its many features include: * Virtually unlimited board sizes * Virtually unlimited number of board layers * Virtually unlimited number of parts....

This is my second-generation guitar reverb circuit. The fidelity is much improved over the earlier design, it is suitable for use as a front-end to a guitar amplifier. This circuit features clipping indicators on the preamp and reverb recovery stages,....

Finally I was able to control an LCD Hitachi display and a 12-key matrix keypad with only one 16F84 or 16F628. In a near future, I will be able to control a full QUERTY-type keyboard and a LCD display. The biggest improvement on this projects was the....

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....

In spite of the improvement of communication link and despite all progress in advanced communication technologies, there are still very few functioning commercial wireless monitoring systems, which are most off-line, and there are still a number of issues to....

This circuit is intended to control a heating system or central heating plan, keeping constant indoor temperature in spite of wide range changes in the outdoor one. Two sensors are needed: one placed outdoors, in order to sense the external temperature; the....

This circuit controls resistive and inductive loads up to 2,500W. Its main functional device is an integrated phase control circuit - Siemens TLE3103. It contains its own power supply, a zero voltage crossing detector circuit and a logic driver. An....

The RF oscillator using the inverter N2 and 10.7Mhz ceramic filter is driving the parallel combination of N4 to N6 through N3.Since these inverters are in parallel the output impedance will be low so that it can directly drive an aerial of 1/4th wavelength.....

In the circuit exist a simple power amplifier 60W in the 8 ohm and 80W in the 4 ohm, with components that sure exist in big quantities. It can be used in home cinema systems or in other uses. With the TR1 we regulate the DC voltage in the output of....

One LED monitors three levels: 50, 70 & 85 dB Useful to detect too noisy environments. This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85....

Many people favor different light and temperature settings for different rooms depending upon their mood or whether they are working or relaxing. The circuit in Figure 1 controls the intensity of the artificial light in a room and monitors the temperature of....

The circuit requires only one power-switching device, and you can use an analog or a digital signal to drive the switching device. The circuit also requires only a few components: a diode, a switching transistor or a MOSFET, an inductor or a transformer, and....

Figure 1 shows a complete circuit for an emergency lamp that operates from a 12V automotive battery. The xenon flash tube requires a 250V-dc anode voltage and a 4-kV trigger pulse. To generate the 250V dc, IC1, a switching regulator controller, and T1, a....

This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added...

This page features basic, visible light photo-detector circuits that can be used to detect trains. These methods would normally be used with the photo sensor mounted between the rails...

This is a slightly revised version of the 6-transistor H-bridge designed by Mark Tilden and found on the BEAM Tek website (now only available via archive). I encourage anyone interested in H-bridges to read Mark's article, as it gives an excellent....

The supply of circuit becomes from a AC line in the J1. This voltage can be from a separate transformer 2X12V (the prices of materials that I give it is for 2X12V AC), from existing coil 12V in their M/T of power amplifier or if it cannot become somebody....

Based on Valvo FD-1A module, TBA120, and MC1310. Operation of the receiver is based on the phase locked loop principle. The FD-1A contains an RF amplifier, oscillator and mixer (made with BF324, BF451 and BF324 transistors, respectively). Tuning is performed....

Using the circuit of 40-metre band direct-conversion receiver descr- ibed here, one can listen to amateur radio QSO signals in CW as well as in SSB mode in the 40-metre band. The circuit makes use of three n-channel FETs (BFW10). The first FET (T1) performs....

Once again my collection of projects creation has been interrupted by another necessity. Patrick and other people have asked me for a circuit of a VHF power amplifier. These circuits are my "standard" building blocks that can be used to amplify RF power....