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
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Simple Microphone Mixer
This relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs.
Dynamic to electret microphone circuit
This is a simple microphone preamplifier circuit which you can use between your dynamic microphone and any equipment designed to work with an electret microhone (2 wire connection to electret capsule). This amplifier amplifies the low level signal to the levels used by electret microphone input and uses the power from the device.
Low impedance microphone amplifier
The circuit is a microphone amplifier for use with low impedance (~200 ohm) microphones. It will work with stabilized voltages between 6-30VDC. If you don`t build the impedance adapter part with T1, you get a micamp for higher impedance microphones. In this case, you should directly connect the signal to C7.
Microphone Voice-Over Circuit
In its simplest form, a voice-over unit is just a microphone and change-over switch feeding an amplifier, the output from the microphone having priority over the amplifiers audio signal when the "push-to-talk" switch is pressed. In this circuit, a preamplifier immediately follows the microphone and is designed to be used some distance away from...
This circuit uses a TBA820 audio 1C to amplify underwater sounds. The microphone must be waterproofed. This project was originally used in a home aquarium to monitor fish sounds.
24 Watt Audio Amplifier
The 24 watt amp is easy to build, and very inexpensive. The circuit can be used as a booster in a car audio system, an amp for satellite speakers in a surround sound or home theater system, or as an amp for computer speakers. The circuit is quite compact and uses only about 60 watts.
What got me interested in building these diminutive devices is the S3FM connector assembly made by Switchcraft. The S3FM is simply a 3.5-inch tube fitted with a male XLR at one end and a female at the other, with enough room in the middle to build a mike pad, low-end rolloff network, polarity reverser, or any number of other useful little...
electret mike amp
This circuit amplifies the output of a regular electret condensor microphone quite nicely.. adjust sensitivity by turning R1
simple mic preamp
this is a very easy circuit to build - all parts can be found at the local electronics shop.
Small LM386 Amplifier
This is one of my favorites. The LM386 is a low voltage audio power amplifier. It can provide 125mW to 750mW, enough for any project that uses audio. This circuit can work with batteries, requieres minimum external parts and works from 4 to 18 Volts (contact the manufacturer or read the technical info. Some versions works only with 5 to 15V.)...
1,5V Earphones Audio Amplifier
This audio amplifier circuit, connected to 32 Ohm impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard. You can also listen to your television set at a very low volume, avoiding to bother relatives and neighbors. Even if you have a faultless hearing, you may...
300HZ - 3KHZ Audio Filter
The human speech apprehend a small area of frequencies, that is extended from 300HZ until 3KHZ. This spectrum is also internationally recognized for the transmission of speech via telecommunications networks. This is also the mainer use of this circuit, one and it can be used in uses that we needed this concrete spectrum of frequencies,...
Microphone balanced preamplifier
A professional suggestion for those interested in improving sound. The circuit constitutes the part of input mixing console sound from the microphone or source of high level . It can be used on it's own or be multiplied to the number of channels required. It includes all the useful functions such as, phantom power , reverse face, signal...
Auto Microphone Muter
If you've crossed the line and play guitar or bass and also sing in a band, you're almost certain to have run into the situation that you step away from the mike to do a solo (or one of those neato, expressive dance steps, or a facial impression of the pain you're pouring out to make these dulcet tones...), and had the mike pick up some...
All vocal eliminators start with the assumption that the lead vocal in a recording is in the center of the stereo field - which means that it is equal amplitude and phase in both left and right channels. Subtracting one channel from the other removes this highly correlated signal while leaving the uncorrelated signals in the channels unchanged....
Microphone Preamplifier LM833
This design was born of frustration with the mic preamp in my Sony R91. It clips at ridiculously low levels, basically it has 28mV of headroom to deal with an input that could be as high as 1800mV (depending on mic & volume), so this design attempts to cure that by : A: Providing a higher electret bias voltage, 9V through a 10k resistor to give...
Microphone Preamplifier BC547B
This is a simple microphone preamplifier circuit which you can use between your microphone and stereo amplifier. This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs. This microphone preamplifier can take both dynamic and electret microphone inputs (preamplifier provides power foe electret...
PC Microphone Preamplifier
Soundblaster soundcard series (SB16, SB32, AWE32 and AWE64) have all a microphone input designed to be used with the electret microphones which come with the soundcard package (some packages) or with separate microphone designed to be used with SoundBlaster soundcards (there are separate microphones and some monitors have built-in microphones...
Operational Amplifier tutorial
Ever since the best decade of all time, the 1970s, people have been able to buy amplifiers in all-in-one chips rather than having to make them out of lots of discrete transistors. This video shows you the basics of op amps and has an example circuit where you build an amplifier to take a tiny microphone signal and amplify it to be audible on earbu
PCM2902 Soundcard with Microphone Input Schematic
Many of us have a pair of headphones connected to the output of the computer sound card us either to enjoy songs, or a game. Very likely your headphones and microphone, which also connect to the appropriate slot your sound card. But at some point broke down the female plug my sound card, and because quite a lot to change the plug when I put the he
Lm318 Microphone preamplifier with tone control circuit and explanation
This electronic project is a simple microphone preamplifier based on the LM318 op amp. The LM318 op amp is operated as a standard non-inverting amplifier. Resistor R1 provides an input path to ground for the bias current of the non-inverting input. The combination of R2 and C2 provides a frequency roll-off below 30 Hz. At 30 Hz and above the gain
Electret mic pre amp
Electret mic pre amp schematic. The op amp provides an amplification of about 30 dB (which is sufficient for the relatively high output level of an electret microphone), this gain depends on the value of resistors R3 and R4. If you want to be able to vary the gain, simply replace the resistor R4 to 120K a 470K potentiometer in series with a resist
Mic Amplifier schematic diagram. This circuit has been tried on three microphones, one from SONY, and then two Chinese, everything works! With the correct assembly of the device starts to work immediately, and does not need tuning.
Mic pre amp
Mic pre amp schematic based TLC251. TLC251 is a Programmable Low-Power Operational Amplifiers. This is indeed a control input, called BIAS (pin 8), which determines the mode of operation. When the pin is worn on the positive potential of power supply, the consumption of the circuit is reduced to a minimum, which is 10 uA (ten micro-amps).
This was a final project for an optics class EE 134 at Stanford. It was an open-ended project to make a fully functioning laser microphone the class was geared to demonstrate optics and photonics in the lab, not necessarily electrical schematics. There are real commercial devices that use lasers to sense sound acoustics from glass surfaces. The
Dynamic Microphone Preamp
This circuit is capable of amplifying the output from a 150-ohm dynamic microphone to line level in a single stage, courtesy of a little thing called an instrumentation amplifier. They`re like op-amps but with settable gain and much better common-mode rejection. They can have very high gain, high precision, low noise, and decent cost per chip; not
Understanding Mouthpiece or Microphone Earpiece and IHF or Buzzer Speakers Circuit on mobile phones
A mobile phones microphone or mouthpiece is a component used to convert sound signal into an electrical signal. The earpiece speaker is the one that converts electrical signal into a sound signal, likewise also the IHF, buzzer or ringer speaker do. A typical and modern designed of mouthpiece circuit is being protected by an EMI- Filter to prevent
Dynamic Microphone Amplifier
Dynamic microphones are versatile and ideal for general-purpose use. They use a simple design with few moving parts. They are relatively sturdy and resilient to rough handling. They are also better suited to handling high volume levels, such as from certain musical instruments or amplifiers. They have no internal amplifier and do not require batte
FM Wireless Microphone
The range of frequencies for the FM broadcast band is 90MHz (MHz = Megahertz or 90 million cycles per second). Because the FM microphone has a variable tuned circuit, it can be tuned to a quiet spot on your local FM broadcast band for the best reception. When the small microphone element is struck by sound, it converts the audio to a change in cu
Computer Microphone by BC547
Balanced Microphone Preamplifier
The preamplifier is intended for use with dynamic (moving coil MC) microphones with an impedance up to 200 © and balanced terminals. It is a fairly simple design, which may also be considered as a single stage instrument amplifier based on a Type NE5534 op amp. To achieve maximum common-mode rejection (CMR) with a balanced signal, the division
Dynamic Microphone Preamp
This is a 3 stage discrete amplifier with gain control. Alternative transistors such as BC109C, BC548, BC549, BC549C may be used with little change in performance. The first stage built around Q1 operates in common base configuration. This is unusuable in audio stages, but in this case, it allows Q1 to operate at low noise levels and improves over
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...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity