With a handful of inexpensive components, a little creativity, and the power of PicBasic, you can build some pretty outstanding robotics creations as Rob Arnold proves with his Ruf-Bot project. RF remote control is just way too cool not to use in your....

Analyze your circuits before you build them! PC-ECAP has been one of the world`s best linear circuit analysis programs. The software will calculate and plot: gain, phase, group delay, impedance, VSWR and return loss. This versatile program can also....

This simple 20 watts audio power amplifier is designed for home-brewed purpose. The L1 should be able to handle a current up to 4A to drive speaker in full load. The distortion is 0.015% @ 1KHz / 20W. This circuit is protected for AC and DC short circuits to....

This circuit provides a digital square wave that can be viewed directly or used to drive other circuits. It used the CMOS 4047 Low-Power Monostable/Astable Multivibrator. As used in Tom Duncan's Adventures with Digital Electronic's Book, to drive CMOS Decade....

Designs for solar-powered applications with low-duty-cycle requirements can often rely on capacitors for energy storage in place of less reliable batteries. Typical applications include solar positioning, telemetry transmitters, chemical pumps, data loggers,....

Agreeable, very close sound imitation Suitable for sound effects, door-bells etc. This circuit generates a two-tone effect very much alike the cuckoo song. It can be used for door-bells or other purposes thanks to a built-in audio amplifier and loudspeaker....

This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the....

This circuit will allow you to connect any tape recorder that has a mic and remote input to a phone line and automatically record both sides of a conversation when ever the phone is in use. You will need to take a couple of voltage readings before connecting....

Each time switch S1 is closed the count on the CD4017 advances by 1 step and the coresponding LED turns on. When the maximium count plus 1 is reached for each circuit the cycle is restarted and repeats...

Observing my "Boss" pedals and how they were switched on and off I figured there must be more to it. It took me only about 4 hours to design and test this circuit, It works very well and I`m really satisfied with it so I`ll be using it in all the effect....

LCD2USB is a open source/open hardware project. The goal of LCD2USB is to connect HD44780 based text LCD displays to various PCs via USB. LCD2USB was meant to be cheap and to be made of easily available parts. It is therefore based on the Atmel AVR Mega8 CPU....

This was designed to flash a pair of LEDs to be mounted on the wing tips of a Parkzone Citabria R/C (remote control) airplane. The unmodified Parkzone Citabria only weights 20 grams (about 0.7 oz), so weight, and therefore the number and size of the....

The circuit can be easily built to a small plastic box with telephone connectors in both ends. The circuit takes about 10-20 mA current, so if the circuit is not in use all the time it is best to use batteries. You can also use small wall transformer to....

This microcontroller fascinated me a lot because I wanted to see what we can do with an 8-pin microcontroller (out of which 2 pins goes to power supply, so actually just 6-pins are left for I/O). So I thought of making my own learning board for this. In this....

The System is fully controlled by the microcontroller AT89S52. It is a popular 8 bit microcontroller. The circuit consists of four switches, in which two buttons are used to increment and decrement the temperature value and the next button is to edit the....

A fast electronic fuse designed to operate on 230V AC with an adjustable trip current. When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is....

This circuit provides a short circuit protected power supply from PC 12V supply voltage. This is particularly handy when working with PC interfacing projects...

Two soft start power supplies. The output voltage slowly increases to the desired output. The output voltage rises slowly and reaches 15 V in 5 seconds. In order to perform this soft-start function, the LM317 voltage regulator IC requires an external....

The design objective was to produce an hFE tester with switched collector currents for the DUT (Device Under Test) covering a range suitable for the selection and matching of output transistors for amplifiers such as the JLH Class-A, ESP DoZ etc. The tester....

A nice circuit for using with audio preamplifiers, or any other circuit that use potentiometer and you need to control it from distance. The circuit includes Infrared transmitter and reciever with motor controller chip BA6418N...

Real-world measurement requires the extraction of weak signals from noisy sources. High common-mode voltages are often present even in differential measurements. The usual approach to this problem is to use an op amp or an instrumentation amplifier and then....

Please operate caution when building this power supply. It is run on standard 117 ac current - and under the right circumstances 117 ac can kill you. Use a plastic enclosure if possible to decrease chances of short-circuiting...

Use this circuit to test if the light coming from your 40khz IR emitter is really emitting the right frequency. The schematic says to use a GP1U5X ir module, but probably any 40khz detector module will work.. I used a GP1U26X module...

This project is used as an electronic private exchange. It has two telephones, which have the intercom facility, and they can be connected to the telephone line. All the functions are controlled by the 8-bit microcontroller AT89C2051 which has an Program....

My circuit adds a transistor, to add feedback, and two resistors, to tailor the range of the control, with the result that a single-turn potentiometer gives a control range of about 2 to 30 microamps. I installed my circuit in a small plastic box, and....

This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of the LEDs would normally be the....

Because of the nixie-tube is a gas tube, it requires relatively high-voltage supply. Judging from archives, from 180 to 300 volts are used for supply voltage. In this project, 270 volts from rectified 100V line voltage directly is used. It is very simple but....

The Hot Springs tanks and circuit board should be mounted in a location that is free of ambient electro-magnetic fields. The input and output jacks are typically placed on a patch panel with other effect`s inputs and outputs. In use, the effects or aux send....

This circuit measures temperature in Celsius scale and displays it on an alphanumeric LCD screen. When temperature rise to 40 C an alarm is activated and at the same time a relay is also activated which drives a fan to keep the temperature at a level.....

This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....

Circ?it to close a relay when any phone extension is off-hook. Uoltage at the gate of the MOSFET sho?ld be negative (1-3 volts) with respect to the so?rce then phones are on-hook. Uoltage at the gate sho?ld be positive (8-113 volts) with respect to the....

The circuit of the transmitter is shown in Figure 1, and as you can see it is quite simple. The first stage is the oscillator, and is tuned with the variable capacitor. Select an unused frequency, and carefully adjust C3 until the background noise stops (you....