Voltage Controlled Music Filter Circuit

A voltage controlled music signal filter circuit is shown where an input attenuator (R10 and R11) limits the signal amplitude presented to the FETs to about 0.1 volt p-p at O VU to ensure low distortion. Output amplifier A7 makes up exactly for this loss. An op amp having external frequency compensation was used here so that this relatively high—gain stage could be tailored for flat response to 15 kHz (a 741 could be used, but would roll off slightly...

Read More

Three Phase Sequence Change Warning Indicator Alarm Circuit

In electric motors, phase sequence in 3 phase configuration is very important. Change in phase sequence  may cause trouble in machines.Here is 1 a circuit which indicates the change in 1 phase sequence by a beeper or an LED. Transistors Tl, T2 and T3 are used. to square the 3 phase waveforms. The resistor value should be such that the transistor gets fully saturated when the base voltage becomes 10V. During negative cycle, the diode at the base...

Read More

Piezo Buzzer Driver Circuit Diagram

Buzzers are small, light, simple to use, and yet provide a loud output signal. They are either of the passive or of the active type. The former are driven by an AF signal source, while the latter feature a built-in oscillator, and require a direct voltage only. This circuit is a double AF oscillator for driving passive buzzers. It ensures a richer out- put sound than normally obtain- able from a piezo buzzer due to the use of two oscillators, N1...

Read More

First LED lamp that replaces a 100 watt incandescent

Already reached the market the first LED lamp that replaces 100 watt incandescent bulb, this was the announcement of Osram Sylvania. She becomes the first to do is replace the new lamp will join the existing line of Ultra LED 40, 60 and 75 watt (equivalent to incandescent powers), it consumes 20 watts and have a lifespan of 25,000 hours about 25 times more than incandescent bulbs.It has a CRI of 80, an illumination of 1,600 lumens and a warm white...

Read More

Environmental Noise Ratio Detector Circuit Diagram

This circuit is called the detector noise environment, and also indicates by means of a flashing LED when exceeding the limit specified in the environmental noise, chosen from three fixed levels. This circuit uses two operational amplifiers, in the first position SW1 circuit is not connected, positions 2, 3 and 4 define the input sensitivity threshold to 85, 70 and 50 dB, respectively.Environmental Noise Ratio Detector Circuit DiagramParts ListR1...

Read More

Dog Whistle for Ronja

Ronja is the author’s dog, a beagle-mongrel,  who seems increasingly often to need to be  called to heel either with a shout or with a  whistle. And so the idea came about for an  electronic dog whistle that could produce  two alternating high-frequency tones. A  design like this has several advantages over  conventional whistles or calling.   Circuit diagram : Dog Whistle for Ronja Circuit Diagram ...

Read More

Simple Solar Battery Charger with LM317 Circuit Diagram

Simple Solar Battery Charger with LM317 Circuit Diagram. This is a solar panel battery charger schematic for AA and AAA rechargeable batteries. A small solar panel would be very good as a source of voltage charger. Building a solar AA battery charger only requires a few components and a simple construction. Solar panels should be well adapted to the battery to be charged or the battery may be overcharged. If you want to charge batteries...

Read More

PIC Controlled Relay Driver

This circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical devices. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is designed more attentively. To minimize the effects of the ac line noises, a 1:1 line filter transformer is used.The transformer is a 220V to 12V,...

Read More

How to Build 1 2 30V 1 5A Variable Regulated Power supply Circuit

How to Build 1.2-30V/1.5A Variable Regulated Power supply, This is simple 1.2-30V/1.5A variable regulated power supply circuit diagram The 110V-AC coming from the powercord is fed to the transformer TR1 via the on-off switch and the 500mA fuse. The 30vac output (approximately) from the transformer is presented to the BR1, the bridge-rectifier, and here rectified from AC (Alternating Current) to DC (Direct Current). If you dont want to spend the money...

Read More

Power On Indicator

Some types of electronic equipment do  not provide any indication that they are  actually on when they are switched on.  This situation can occur when the back-light of a display is switched off. In addition, the otherwise mandatory mains  power  indicator  is  not  required  with  equipment  that  consumes  less  than  10 watts. As a result, you can easily forget ...

Read More

Phonon Preamplifier Circuits Diagram

In recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phonon preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these webpages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency...

Read More

High Performance 12V 20W Stereo Amplifier

High-Performance 12V 20W Stereo Amplifier. Amplifiers which run from 12V DC generally don’t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the power and low distortion boxes. With a 14.4V supply, it will deliver 20 watts per channel into 4-ohm loads at clipping while harmonic distortion at lower power levels is typically less than 0.03%. This is an ideal project for anyone wanting a compact stereo...

Read More

Build a Toggle Touch Switch Using Two Inverter Gates

We  can make a simple touch switch using only two inverter gates, two resistors, and two capacitors. The schematic diagram of the circuit is shown in the figure below. At power up, the output (of U1A) will be high, and the inverting output will be low because U1A gate will be triggered to ground level by C2. After triggered, the low level of U1A input is maintained by U1B output via R2.If we touch the pad at this condition, where the output...

Read More

Save Your Ears A Noise Meter

‘Hello… HELLO! Are you deaf? Do you have disco ears?’ If people ask you this and you’re still well below 80 , you may be suffering from hearing loss, which can come from (prolonged) listening to very loud music. You won’t notice how bad it is until it’s too late, and after that you won’t be able to hear your favorite music the way it really is – so an expensive sound system is no longer a sound investment. To avoid all this, use the i-trixx sound...

Read More

Surf Sound Synthesizer

Many people who live close to the ocean have the benefit of being lulled to sleep by the sound of the surf. This circuit may provide a similar benefit to all those poor unfortunates who don’t live near the seaside but who do have the small consolation that they don’t have to worry about rust and corrosion in a salty atmosphere. The circuit consists of four unsynchronised oscillators which are mixed together to modulate a white noise source...

Read More

Rolling Shutter Motor Control

An electrically operated rolling shutter usually has a standard control panel with a three-position switch: up, down and stop. If you would like to automate the opening and closing with a time controlled switch, a few additional wires will have to be connected. Typically, the controls are implemented as indicated in the schematic ‘Normal Situation’. If this is indeed the case, then you can see in ‘New Situation’ how the shutter can be automated...

Read More

30W Power Audio Amplifier Circuit Diagram

TIP141 si a npn silicon power darling tons designed for complementary use with TIP145, TIP146 and TP147. Can stand up to 125 W at 25°C Case Temperature, 10 A Continuous Collector Current and has a minimum hFE of 1000 at 4 V, 5 A. This home audio amplifier can output 30W with a +- 32V symmetric power supply. If you want a stereo power amplifier please check out the other schematics. R1=1Kohm R16-17=270ohm D1=9.1V 0.4W zener R2=47Kohm R18=22ohm...

Read More

Simple Park Assist Circuit Diagram

Build a  Park Assist Circuit Diagram. This is a Simple Park Assist Circuit Diagram. This Park Assist circuit was designed as an aid in parking the car near the garage wall when backing up. LED D7 illuminates when bumper-wall distance is about 20 cm., D7+D6 illuminate at about 10 cm. and D7+D6+D5 at about 6 cm. In this manner you are alerted when approaching too close to the wall. All distances mentioned before can vary, depending on...

Read More

Monitor voltage and 5VDC and 12VDC Circuit Diagram

This circuit is a voltage monitor which operates on fixed testes ± 5 VDC and ± 12 VDC, and is easily constructed as shown in Fig. It is considerably simpler than the normal display using comparators and AND gates. The circuit is not intended to indicate the level of entries. If one of the testes fail, for example, -5 V line fails, the transistor Q3 remains on but the base-emitter junction of T2 is not, so that this transistor is cut off. When this...

Read More

Simple USB Standby Killer

When turning a computer on and off, various peripherals (such as printers, screen, scanner, etc.) often have to be turned on and off as well. By using the 5-V supply voltage from the USB interface on the PC, all these peripherals can easily be switched on and off at the same time as the PC. This principle can also be used with other appliances that have a USB interface (such as modern TVs and radios). USB Standby Killer Circuit Diagram...

Read More

Mains Voltage Monitor

Many electronics hobbyists will have experienced the following: you try to finish a project late at night, and the mains supply fails. Whether that is caused by the electricity board or your carelessness isn’t really important. In any case, at such times you may find yourself without a torch or with flat batteries. There is no need to panic, as this circuit provides an emergency light. When the mains fails, the mains voltage monitor turns on...

Read More

Car Battery 12v Charger

The usual chargers of battery automotive, are simple and cheap appliances that charge continuously the battery, with a rythm of few amperes, for the time where the appliance is ON. If the holder do not close in time the charger, the battery will overcharge and her electrolytic faculty are lost with evaporation or likely exists destruction of her elements. The charger of circuit exceeds these faults. It checks electronic the situation of charge of...

Read More

New 4 Channel Portable Audio Mixer

The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs. The three main modules are:Input Amplifier Module: a low noise circuit equipped with a variable voltage-gain (10 - 100) preset, primarily intended as high quality microphone input, also suitable...

Read More

A Car Battery Monitor

A close call on the road can really focus your mind on the importance of having a battery monitor in a car. I had been enjoying a pleasant week of travelling around the countryside at a leisurely pace and taking in the beautiful scenery each day. It wasnt until the final day, with the big rush to return home, that I had to drive at night.My home is deep in the country and on the road I was travelling the closest petrol station may be 80km away. I...

Read More

Little Door Guard

If some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig. 1) uses readily available, low-cost components. For compactness, an alkaline 12V battery is used for powering the unit. Input DC supply is further regulated to a steady DC voltage of 5V by 3-pin regulator IC 7805 (IC2). Fig. 1: Circuit of the door guardAssemble the unit on a general-purpose PCB as...

Read More