The AY-3-8910/8912 is a register oriented Programmable Sound Generator (PSG). Communication between the processor and the PSG is based on the concept of memory-mapped I/O. Control commands are issued to the PSG by writing to 16 memory-mapped registers. Each....

The small 8-pin PIC12C508 is pre-programmed to generate our 38KHz carrier frequency by simply pulsing I/O-pin GP1 (shown above). The PIC will generate either 38KHz or 40KHz, depending on the state of GP3 when power is first applied. If you connect GP3 to....

Tube amplifiers designed for headphones have the principal property that they can be used as preamplifiers too. In most cases, the output impedance of a tube headphone amplifier is (or should be) less than the output impedance of a tube preamp. This....

If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card. This sound card can be powered from USB port and has one stereo output. You don’t need to install any driver for Windows XP and Vista, because....

I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....

This circuit has been designed to alert the vehicle driver that he has reached the maximum fixed speed limit (i.e. in a motorway). It eliminates the necessity of looking at the tachometer and to be distracted from driving. There is a strict relation between....

Because it uses few parts, a printed circuit board is not necessary; components can simply be soldered to one another. However, a box is desirable for operating convenience. The case and aerial from a discarded toy walkie-talkie was used in the prototype....

Halloween is coming up and it's time to do some pranks. Everyone likes Halloween and I'm no exception. Every year me and my wife decorate the house with lot's of bugs, spider webs, creepy posters and of course lot's of Halloween candy. While making the....

Emits a carrier that sweeps the 925-960 MHz cellular tower transmitter band (handset receive band)...

This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....

This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer. This circuit takes it power from a PC. The power....

This is an improved version of the audio interface commonly used to connect a computer soundcard to a transceiver`s receive and transmit audio circuits. This kind of interface is used by computer programs that send and receive SSTV, RTTY, CW, PSK31 and....

This implementation is adapted to rebroadcast the output of a CD player, television receiver, or radio receiver. I use it so that I can move about the house and listen to my favorite programs without disturbing others. Within and the house, I find that I can....

This circuit allows you to record audio from a telephone line into a tape recorder or computer soundcard. Most of the parts for this circuit can be scrounged from an old modem, with some work, it is possible to rewire the modem circuitry and use the old....

When an antenna is attached, (or even if not, in the presence of a strong RF field) the field strength meter has a moving coil meter to indicate relative field strength. The box holds a Schottky diode detector, a DC amplifier, and a meter display. If the....

The above diagram is a standard low-pass telephone line filter (L1,C1,L3,C2). L2 and L4 are needed since we're dealing with the 'Tip' and 'Ring' of a phone line which may carry up to 90VAC. I used a similar circuit on 3 phone-lines back in the early 80's....

This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. Using a stereo microphone the circuit must be doubled. In....

The interface uses a PIC16F876 microcontroller and not much else. It performs channel mixing, current limiting, and noise rejection. Push the stick forward, both motors move forward, move the stick to the left and the robot moves left. It makes the robot....

Rectifier circuits based on semiconductor diodes typically handle voltage levels that greatly exceed the diodes` forward-voltage drops, which generally don`t affect the accuracy of the rectification process. However, the rectified signal`s accuracy suffers....

This project provides an simple F1 motor racing style 5 light race start sequence with a random delay that you can use on a real race track, kart circuit or even your slot-car circuit. Operation is simple; when the start button is pressed all the LED....

Most audio amplifier systems must have preamplifiers with many different characteristics. These include high-gain linear response for magnetic microphones, low-gain linear response for tuners, and high-gain RIAA equalization for magnetic phone cartridges. To....

is circuit was requested from an email. It will allow your car headlights to flash on and off at the same time or it will cause them to flash alternately. The circuit is based on the 555 timer. It is used in the astable mode. The 555 timer output will go....

You can use a low-cost PC sound card as an analog-function generator by controlling the PC with the program "SoundArb." [To obtain SoundArb, download di2409setup.exe, a 1.06-Mbyte self-extracting installation program.] The program generates standard....

This tiny circuit comprising of a single 3 terminal IC UM66 can be built small enough to be placed inside a greeting card and operated off a single 3V flat button cell. There is not much to the circuit. The UM66 is connected to its supply and its output fed....

The amp is built according to the Morgan Jones design. In the spirit of DIY, I made a few modifications. I did not change the circuit topology at all, but used Svetlana 6N1P tubes, as noted. I also used a conventional power supply instead of the wall....

In recent years more and more, have a tendency ket demanded higher reimbursement structures with lights and music lovers in general and manufacturers of tube amplifiers. The reason, in their view is that the sound of tubes is more sweet, how rich and....

Tihs circuit has: automatic switch on on rear gear. led-bargraph display. audible bleep on last led. "good old" design style, no microcontrollers! Based on an ultrasonic amplifier from an article seen on a 1982 magazine, it was once installed on the rear....

This is a very simple circuit to interface a current loop sensor to an input which is designed for a voltage, such as that from a standard potentiometer. This page is technical so that interested persons can build the circuit themselves, but 4QD can also....

This encoder can transmit the state of up to 16 TTL digital inputs using an RF or infrared transmitter. When enabled, the included modulator automatically generates the 38kHz IR carrier. Containing a PIC microcontroller, the circuit is very flexible. You....

This small but useful circuit is a DC voltage convertor for using 6V devices with car battery voltage. The maximum output current is dependent if the T1 is covered with a proper heat sink or not. You can use the circuit to drive devices that they sink....

The described device is used to convert the digital signal format S / PDIF (AES3) to analog. It can be used for any device with uncompressed digital audio output (desktop CD or DVD, minidisk, sound card PC CD-ROM). Separate transmitter can improve the signal....

This adaptor will capture plots or prints of your GPIB instrument to your PC through the serial port. It fills the need of anybody who has a test instrument with the GPIB port and likes to get the screen dump on his PC without any GPIB card. Project based on....