Page 1 New Circuits

Quick view of Mosfet 75W Power Amplifier

The MOSFETS we are dealing with are three terminal devices which are used to control electron flow in a circuit. Two of the pins (the source and drain) pass the current, and the third pin (the gate) is used to control the current. The control of current, as seen from the outside, is accomplished by placing a voltage on the gate relative to the source pin. In the case of the N- Channel MOSFET, which approximates tube operation, increased current flows from the drain through the source in response to positive gate voltage, with respect to the source voltage (fig. 2b) If you wish more current, make the gate-to- source voltage more positive (for less, make it less positive). Conduction in the N-channel MOSFET will start generally at about 4V: less than 4V, no current; more than 4V, current flows...

Class A 40W into 8 Ohms Amplifier

Class A 40W into 8 Ohms Amplifier

Both parts of the circuit are biased with the constant current sources as shown, and the signal from the collector of the PNP is followed by the Darlington class A output stage whose idle current is controlled by the bias circuit. The transistors Q1 and Q2 form the traditional differential pair but there are some twists added to the feedback and input networks. The feedback circuit formed by R3 R4 R5 C2 C4 is used to bootstrap the input impedance to a nominal value of 40k Ohms while providing a low impedance path for the input bias currents. This results in a high input impedance with low offset voltage. The capacitor C4 creates a high frequency input to the negative feedback circuit which rolls off the high frequency gain of the amplifier...

Digital Thermometer

Digital Thermometer

A device designed for measuring time and temperature used in chemistry laboratory. The circuit employs a 89C4051, 20-pin CMOS Microcontroller with built-in 4kB code memory. Temperature was measured by LM35D, National Semiconductor Temperature sensor producing 10mV/°C. The CA3162, 3-digit DVM converts dc output provided by LM35D and sends BCD output to port1 (P1.0-P1.3). The program resided in code memory of 89C4051 was written in ‘C’ language, thermo.c. The program read BCD output from the A/D converter, performs digital filtering,10-point moving average, and sends the output reading to a 16x1 line LCD display. A 10ms cputick was used as a timebase producing 1 s for time counting. The LCD displays time in 1 s and temperature in 0.1°C resolutions...

Monostable to bistable relay with momentary switch

Monostable to bistable relay with momentary switch

This circuit could be used to drive a monostable relay by a singol momentary switch. Powered by 24 Volts it works for a 12 Volts relay. When the button is pressed Q1 is energized and the capacitor charges, while the relay coil is shorted. Once the button is released the relay turns on. Note that Q1 is powered by the capacitor until the relay switch (10-6) closes...

Sounds from the IC IT82207

Sounds from the IC IT82207

This circuit is able to take you to the world of the Wild West. For this it uses the integrated 18-pin IT82207 (IC1) of Holtek, which literally takes care of everything. You have to do is add a few accessories, including a loudspeaker and six selector switches. ..

Simple humidity detector

Simple humidity detector

The main (and only) job of this circuit is to activate a buzzer or a relay, each time the level of humidity takes a specific value. Main stage is a memory based on a flip-flop consisting of gates and IC1a IC1 b. The output of this step activates an oscillator (IC1c), which in turn leads to a piezoelectric speaker. At the start of operation of the circuit, the flip-flop is driven to logical '0' or through the C1 or through C2. From the moment you excited, the reintroduction of the peace achieved through the switch S1, which however is insufficient if the sensor 82 continues to be wet...

Lighting auto controller

Lighting auto controller

The governor following is intended to regulate the light intensity incandescent 220 V. The components in a relatively few, which means it can easily be mounted onto a small plate. After the build, we recommend you place it inside the box which is flush mounted switch ON / OFF the lamp. Setting the switch to ON, the lamp will light after about 400 msec, a delay is probably negligible. But when the state enters the ON OFF, then mesolathei a period of 20 sec, the brightness of the lamp remains unchanged to start falling out soon after. ..

Infrared approach detector / sensor

Infrared approach detector / sensor

Basic operation of the monitor attached to the circuit is to detect objects (obstacles), at distances ranging from a few millimeters to and a few centimeters. Depending circuits used in industry and hospitals. The position sensor IC2 optoapomonotis used a type of Siemens SFH900 someone similar. The sign shows, led to a phase locked circuit (contained in IC1), which compares with signal frequency an oscillator which is also located within the same chip. For as long as the frequencies of two signals coincide, the pin output of IC1 (pin 8) is still reasonable 'O'. ..

PIC16CS4 Programmer

PIC16CS4 Programmer

Most of you will certainly already installed on your computer one of the many software tools move freely from hand to hand and is suitable for programming the PIC 16C84. One of the most popular of this kind is the RIR02 of Silicon Studios. The circuit described below, is perhaps the simplest PIC programmer that can work seamlessly with the program RIR02. This guide allows RIR02 communication with the programmer, through the parallel port (Centronics). ..

Multi-color LED driver

Multi-color LED driver

Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can light up as independent of each other. There are only two colors that can produce this dual LED. ..

Automatic switch for batteries

Automatic switch for batteries

Nowadays the batteries are gaining more and more power, being the only components that fail to provide energy for portable electronic devices. The evolution is rapid, leading manufacturers electronic equipment to attempt to minimize the consumption of their products so that they can operate for several hours using simple batteries trade. In spite of the efforts of manufacturers, the device will absorb a zero power not yet invented. Thus, both small and if the current device is mathematically certain that at some point, after a few hours, days or ethdomades, the battery-drain '. The purpose of the circuit will describe below, is to keep 'alive' batteries for the maximum time, minimizing unnecessary consumption...

Mono audio panoramic interference (pan pot)

Mono audio panoramic interference (pan pot)

The circuit spectator interference enables implantation mono sound at any point between stereo speakers. When P1 is in the middle of his journey, there is strengthening or weakening of the mark the entrance to the exit in any of the two channels. When the potentiometer placed elsewhere, away from halfway, the signal in one channel is supported 3dB more than the other. The input stage is a buffer (IC1). Inverts the input signal to ensure compliance with this phase of the output (Next steps' and reverse them the signal they receive to entry). The resistance value entry identifies to that of R 1 (1 A KO). The output buffer is driven in stereo amplifiers IC2 and IC3...

Modem shutdown Indicator

Modem shutdown Indicator

The circuit has been designed to accommodate all those who dedicate many hours of their lives by exploring the endless pages of this site. Despite the fact that it consists of only three components (Most were not little!), Is able to provide an indication of whether it actually released the telephone line after a long connection via modem to the network. This can be particularly useful, since there In many cases, the computer claims that the telephone network connection has been interrupted, but the modem for some reason keeps the line engaged...

Temperature measurement using two cables

Temperature measurement using two cables

In those cases we want to measure the temperature in an area far from where it is. The imaging unit installed, you should find some way to connect the latter with the necessary sensor. The cables we use most often will have three two conductors for power sensor and one more to carry the signal representing the temperature. But it may have only two, assuming that one will carry the potential of land and the second supply voltage with the signal temperature. This is possible if used as sensors or the LM334 or the LM335. The disadvantage arises but with them is that the temperature display is provided for reference the absolute zero (Kelvin scale), which most often is not as convenient as we would like. If so the issue is a signal proportional to the temperature scale Celsius which in everyday life, you should use a different sensor, such as the LM45. ..

Low Power Voltage Reference

Low Power Voltage Reference

The voltage reference circuit described below, is a special implementation of current source LM334. Characterized by a very small temperature coefficient metatholio output voltage and consumes only 10uA room temperature. This current fluctuates by a few uA, when the ambient temperature varies significantly. The positive rate of temperature change LM334 offset by the negative of the contact base emitter transistors has a direct thermal coupling with the integrated. To achieve the lowest possible temperature coefficient, it is necessary to adjust the output voltage of 1,253 V source to the arrangement easily done through R1. ..