Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
Liquid Sensing Circuits
Light Sensing Circuits
Voltage Detector Circuits
Air-Gas Detection Circuits
Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
Free Energy Circuits
AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
Digital to Analog
Analog to Digital
Data Bus Circuits
Voltage to Pulse
Current to Voltage
Frequency to Voltage
RF Converter Circuits
Sine to Square Wave
Voltage to Current
voltage to frequency
Period to Voltage
Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Mini-box 2W Amplifier
This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone output. Of course, in most cases you will have to make two boxes to obtain stereo.
12 Volt 20 Amp Solar Charge Controller
A 12 Volt solar power system can provide power to a wide variety of devices. Some examples include: lighting systems, cellular phones, CB and Ham radios, car stereos, televisions, recording equipment, fans, water pumps, and other low voltage DC loads. With the addition of an inverter, the DC power can be converted to 110 Volts AC for powering an...
12 to 120 Volt Inverter
It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to much power the circuit will shut down all by itself. The output of this circuit is a square wave so there may be some noticeable hum on audio units plugged into it.
NTE789 Stereo Multiplex Decoder
Figure 1 shows the block diagram for the NTE789. The input signal form the detector is amplified by a lowdistortion preamplifier and simultaneously applied to both signal, generated by a local voltagecontrolled oscillator (VCO), is counted down by two frequency dividers to a 38kHz signal and to two 19kHz pilottone supplied by the FM detector...
Stereo Decoder Circuit
No description available.
Stereo Decoder for FM Tuner
No Description available.
Mobile MP3 Player PC
The CPU is an AMD K5 running 75 MHz. Theres 16 meg ram, and the operating system is Linux (Red Hat 5.2). MPG123 handles the MP3 decoding, and I wrote a control program in Perl. I built the remote control in an old Blaupunkt CD-changer remote case which I emptied completely. It now has a backlit 40x2 LCD and a PIC 16F84 microcontroller. It...
Voltage Controlled Panner
The control voltage is fed into the first half of a 1458 op-amp, this stage inverts the signal and sets the offset and gain for the right channel gain control circuit. This signal is then fed into the second half of the 1458 op-amp which inverts the voltage again and generates the signal for the left gain control circuit. The 10K trimmer adjusts...
PC Spectrum Analyzer
The spectrum analyzer circuit takes a stereo input and displays a volume by frequency display on a standard PC monitor. Finding the amplitude of a waveform at each frequency and then mapping this to the screen using a discrete number of levels achieve this. To complete this process, four stages are needed. The first stage is the loopback...
22 Watt Stereo Amplifier
This circuit is very basic to build and puts out great power for your car or home. Keep all leads as short as possible.
25 Watt MosFet Audio Amplifier
Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 at...
50 Watt Amplifier
This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device.
Portable Mic Preamplifier
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 this case, two separate level controls are better than a dual-ganged stereo...
Voltage Controlled Panner
This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems. The circuit is mainly here for historical reasons, a higher quality panner may be built with the National Semiconductor LM13700 dual...
Stereo Encoder for FM transmitters
This stereo encoder is a halfway between analogue and digital processing. It combines the best from both domains to provide high-quality and easy to build device. The sampling frequency used in this stereo encoder is 97 times (!!!) higher than the pilot tone frequency. This makes very easy to reject all spectral residues around the sampling...
2 lines FET Audio Mixer
This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.
Stereo Audio signal Isolator
This circuit is useful for removing ground loop hum on a remote line level audio signal line. It can be used to to connect a computer sound card to a stereo amplifier`s line input. Other uses include tapping into a line level signal for powering a remote amplifier, and removing common mode ground interference on 12 Volt audio equipment such as a...
Audio stereo Panner
This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems.
Panner Waveform Generator
This device is a microprocessor controlled waveform generator that can be used for driving a voltage controlled stereo panner for music applications. Panning is simply the movement of a mono audio signal between the left and right channels of a stereo sound system . The circuit can also be used to drive other voltage controlled modules that...
Stereo Headphone Amplifier
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 control is a single 47k linear potentiometer, which at center adjustment prevents even attenuation to both left and right input signals. If the balance control is moved towards the...
2x10 LED VU Stereo Meter
I like to see lights move to music. This project will indicate the volume level of the audio going to your speakers by lighting up LEDS. The LEDS can be any color so mix them up and really make it look good. The input of the circuit is connected to the speaker output of your audio amplifier. You want to build two identical units to indicate...
4 lines Stereo Mixer
With this circuit you can mix four separate audio inputs. Each input will accept high or low impedance microphones, phonograph, tape or aux signals. You can adjust the gain of each input by adjusting each respective pot. With the Stereo/Mono switch you can combine just inputs 1,2 and 3,4 or in the Mono position combine all four inputs.
No Description available.
There are many ways to create a stereo effect. If you were miking a piano, a string section, or some other large sound source, you`d probably stick up a pair of directional mikes and assign them left and right. But what if you want to "enlarge" a lead vocalist? Or, how about other inherently mono instruments like an electric guitar or a...
Stereo VU Meter
This is it. It`s a STEREO LED LEVEL METER. It`s the cheapest and best bar graph display available and best of all, it uses readily available components. You only need a handful of LEDs, 22 transistors, some resistors, diodes and a set of electros - it doesn`t require any chips.
EM Field Probe with Meter
This tester is designed to locate stray electromagnetic (EM) fields. It will easily detect both audio and RF signals up to frequencies of around 100kHz. Note, however that this circuit is NOT a metal detector, but will detect metal wiring if it conducting ac current. Frequency response is from 50Hz to about 100kHz gain being rolled off by the...
Designed for self-powered 8, 4 & 2 Ohm loudspeakers. This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone output. Of course, in most cases you will have to make two boxes to obtain stereo. Bass-boost...
Panner Waveform Generator
This device is a microprocessor controlled waveform generator that can be used for driving a voltage controlled stereo panner for music applications. Panning is simply the movement of a mono audio signal between the left and right channels of a stereo sound system. The circuit can also be used to drive other voltage controlled modules that...
FM stereo multiplex generator
The design philosophy for this circuit was centered on replacing all of the op-amp circuitry found in the earlier circuits with discrete transistors and LC filters. The previous circuits had many (high quality) op-amps in series, this resulted in audible distortion, especially on "ess" sounds. The discrete transistor amplification stages in this...
Micro Power FM Broadcasting
Here are some utility circuits for use with the Ramsey FM10a, and other small FM stereo transmitter kits. This information may be helpful for setting up a micro powered FM radio station. The FM10a and similar kits tend to put out a low quality, broad band output signal. This is not a big problem with a 5-10 milliwatt signal, but amplifying the...
HI-FI Stereo Encoder / Multiplexer
This stereo encoder is the perfect solution for those looking for a high quality stereo sound transmission at a low cost. This stereo encoder produces an excellent crystal clear stereo sound and very good channel separation that can match with many more expensive stereo encoders that are available on the market. It is all possible thanks to a...
200mW FM transmitter
Here is the latest and greatly improved TX200 VFO/VCO FM transmitter. The most versatile transmitter to date that can be turned into high fidelity stereo PLL based 200mW FM transmitter. It is a perfect circuit for transmitting your music around the house and yard. TX200 uses only two coils; one in the oscillator and the other one in the 200mW...
Audio Filters Circuits
Audio Amplifier Circuits
Audio Oscillator Circuits
Audio Mixer Circuits
Audio Equalizer Circuits
Audio Tone Balance Circuits
Beeper Buzzer Circuits
Vacuum-Tube Valves Circuits
Musical & Effects Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial