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Dual Power Supply Circuit For Amplifiers . A power supply suitable for use with the 60W amplifier presented in the predefining project is perfectly simple, and no great skill is required to build (or design) one.  There are a few things one should be careful with, such as the routing of high current leads, but these are easily accomplished. The first thing to choose is a suitable transformer.  I suggest toroidal transformers rather than the traditional "EI" laminated types because they radiate less magnetic flux and are flatter, allowing them to be installed in slimmer cases.  They do have some problems, such as higher inrush current at switch on, which means that slow blow fuses must be used. For the 60W amplifier, a nominal (full load) supply of +/- 35V is required, so a 25-0-25 secondary is ideal - however, see Updates, below.  The circuit for the supply is shown below, and uses separate rectifiers, capacitors and fuses for each channel.  Only the transformer...

These days, music is a major hobby for the young and not-so-young. Lots of people enjoy making music, and more and  more dream of showing off their talents on  stage. But one of the major problems often encountered is the cost of musical equipment. How many amateur music groups sing through an amp borrowed from a guitarist or bass player?  This is where the technical problems arise not in terms of the .25” (6.3 mm)  jack, but in terms of the sound quality (the words are barely understandable) and volume (the amp seems to produce fewer decibels than for a guitar). What’s more, unpredictable feedback may cause damage to the speakers and is very unpleasant on the ear. This cheap little easy-to-build project can help solve these technical problems. A guitar (or bass guitar) amplifier is designed first and foremost to reproduce the sound of the guitar or bass as faithfully as possible. The frequency response of the amp doesn’t need to be as wide or as flat as in hi-fi (p...

PARTSIM http://www.partsim.com SPICE Simulator AC/DC/Transient Sims Waveform Viewer Simulation Features   -  PartSim includes a full SPICE simulation engine, web-based schematic capture tool, and a graphical waveform viewer.  Browse Examples  -  Try out a sample simulation and see  PartSim in action. No registration is  required. Browse Examples Digi-Key Integration  -  PartSim includes an integrated Bill-Of-Materials manager that lets you assign  Digi-Key Part Numbers to your models. CIRCUITLAB https://www.circuitlab.com/ Choosing the right design tools makes your job easier. Design with our easy-to-use schematic editor. Accurate analog & digital circuit simulations in seconds. Professional schematic PDFs, wiring diagrams, and plots. No installation required -- try it instantly. DOCIRCUITS http://www.docircuits.com Build Circuits -Have fun building and burning circuits Over 541238 Simulations Share - Your Design with community Test ...

This inexpensive, fully transistorised switch is very sensitive to sound signals and turns on a lamp when you clap within 1.5 metres of the switch. One of its interesting applications is in discotheques, where lights could be turned on or off in sync with the music beats or clapping. Sound-Operated Switch for Lamps Circuit Diagram The condenser microphone senses the sound and converts it into electrical variations. The electrical signals are amplified by the two-stage direct-coupled (DC) amplifier formed by transistors T1 and T2 and fed to the switching circuit. The switching circuit comprises transistors T3, T4 and T5, which conduct only when the circuit senses sound signals. Transistor T5 supplies sufficient gate voltage to the triac to drive the 230V lamp. The regulated 12V DC power supply for the circuit is derived from AC mains by using resistor R14, diode D1 and zener diode ZD1. The circuit can be assembled on any general-purpose PCB. Soursed By: EFY: Author Pradeep G.

Simple Automatic Switch For Audio Power Amplifier. Circuit of an automatic switch for audio power amplifier stage is presented here. The circuit uses stereo preamplifier output to detect the presence of audio to switch the audio power amplifier on only when audio is present. The circuit thus helps curtail power wastage. IC1 is used as an inverting adder. The input signals from left and right channels are combined to form a common signal for IC2, which is used as an open loop comparator. IC3 (NE556) is a dual timer. Its second section, i.e., IC3(b), is configured as monostable multivibrator. Output of IC3(b) is used to switch the power amplifier on or off through a Darlington pair formed by transistors T1 and T2. IC3(a) is used to trigger the monostable multivibrator whenever an input signal is sensed. Circuit diagram: Automatic Switch For Audio Power Amplifier Circuit Diagram Under ‘no signal’ condition, pin 3 of IC2 is negative with respect to its pin 2. Hence the output of IC2 is lo...

A 60-dB Range Compressor circuit shown in the schematic diagram below can produce consistent output of 1.4V P-P over entire 60dB range that is very useful for audio level/volume stabilization.  As the main components, this circuit uses a 741 opamp and JFET. With input range of 20mV to 2oV, this circuit has delay time of 0.4s (decay time)  and response time of 1.2ms (attack time). The JFET is used as  voltage-controlled resistor in peak-detecting control loop of 741 opamp. Here is the schematic diagram of the circuit.  A 60-dB Range Compressor schematic diagram

This is the Modem for Digital Modes Circuits Diagram. Ham Com is a modem for almost all types of digital transmission for radio amateurs. It can be used to RTTY, ASCII, NevTex, Sitor, Amtor, Fec, CW, FSK, etc.. The modem is simple and can even be used for receiving faxes and SSTV wx-using JV-FAX software.  Modem for Digital Modes Circuits Diagram To use this modem, you need a PC with serial port, Software HamCom and radio equipment.

Normally, the refrigerator lights  are  yellow in colour  and  go  bad  very  often. If you want a long-lasting white light  for  your  refrigerator, this circuit is especially for you.The circuit is easy to install inside the refrigerator. Also, it consumes very  little power compared to the traditional yellow bulb.   Circuit diagram : White Light For Refrigerator Circuit Diagram   The circuit is transformerless and uses a capacitor for providing the power supply to the white LEDs. Mains input is fed to capacitor C1 and resistor R1, rectified by a bridge rectifier comprising diodes D1 through D4, and filtered by capacitor C2 to provide sufficient voltage to drive the white LEDs. Resistor R2 limits the current flowing through the LEDs. The circuit uses 16 bright white LEDs in 2×8 parallel connection configuration.   Assemble the circuit on a general purpose PCB along with 16 white  LEDs. Connect the LEDs in series with resistor R2. Take out the two wires from the usual bulb connecti...

On different forums, I often find people asking for help in calculating the required turns for a ferrite transformer they are going to use in high-frequency/SMPS inverters. In a high-frequency/SMPS inverter, the ferrite transformer is used in the step-up/boost stage where the low voltage DC from the battery is stepped up to high voltage DC. In this situation, there are really only two choices when selecting topology – push-pull and full-bridge. For transformer design, the difference between a push-pull and a full-bridge transformer for same voltage and power will be that the push-pull transformer will require a center tap, meaning it will require twice the number of primary turns as the full-bridge transformer. Calculation of required turns is actually quite simple and I’ll explain this here. For explanation, I’ll use an example and go through the calculation process. Let’s say the ferrite transformer will be used in a 250W inverter. The selected topology is push-pull. The power source...

Simple Automatic Switch For Audio Power Amplifier. Circuit of an automatic switch for audio power amplifier stage is presented here. The circuit uses stereo preamplifier output to detect the presence of audio to switch the audio power amplifier on only when audio is present. The circuit thus helps curtail power wastage. IC1 is used as an inverting adder. The input signals from left and right channels are combined to form a common signal for IC2, which is used as an open loop comparator. IC3 (NE556) is a dual timer. Its second section, i.e., IC3(b), is configured as monostable multivibrator. Output of IC3(b) is used to switch the power amplifier on or off through a Darlington pair formed by transistors T1 and T2. IC3(a) is used to trigger the monostable multivibrator whenever an input signal is sensed. Circuit diagram: Automatic Switch For Audio Power Amplifier Circuit Diagram Under ‘no signal’ condition, pin 3 of IC2 is negative with respect to its pin 2. Hence the output of IC2 is lo...

This is an AM radio power amplifier circuit. What is different with other general amplifier is that this circuit has a low-pass filter (passive type), built using R1C1 to limit the input-output frequency response. Additionally, a ferroxcube K5-001-001/3B with 3 turns of wire is used as ferrite bead  at output filter. All components should be spaced very close to  the IC.  The ground and speaker lead must be twisted tightly. The supply lead and supply ground also must be twisted very tightly. Here is the schematic diagram of the  circuit.  Audio Power Amplifier for AM Radio Circuit Diagram

Bipolar Power supply for Battery Instruments Circuits Diagram. To generate regulated ± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery.  When the supply is switched off, there is the risk of a reverse bias being applied across the regulators, if there is significant inductance or capacitance in the load circuit.Diodes across the regulators prevent damage. When the power supply is switched on, the two switches do not act in unison. There is a probability that one or the other regulators will be latched hard off by the other. To prevent this, D3 and D4 are Zener diodes so that ± 5-V rails are pulled up by the batteries until the regulators establish the correct levels. Bipolar Power supply...

Circuit Diagram 7-Element Graphic Equalizer IC for Hi-Fi AN7337N Datasheet for AN7337N: Download

These days, music is a major hobby for the young and not-so-young. Lots of people  enjoy  making  music,  and  more  and  more dream of showing off their talents on stage. But one of the major problems often encountered is the cost of musical equipment. How many amateur music groups sing  through an amp borrowed from a guitarist or bass player? This is where the technical problems arise not in terms of the .25” (6.3 mm)  jack, but in terms of the sound quality (the words  are barely understandable) and volume (the amp  seems to produce fewer decibels than for a guitar). What’s more, unpredictable feedback may cause damage to the speakers and is very unpleasant on the ear. This cheap little  easy-to-build project can help solve these technical  problems. Vocal Adaptor for Bass Guitar Amp Circuit Diagram A guitar (or bass guitar) amplifier is designed first and foremost to reproduce the sound of the guitar or bass as faithf...

The crossover network is intended for use when an existing audio installation is to be extended by the addition of a subwoofer. Often, this additional loudspeaker is one that has been lying around for some time. If its frequency response extends down far enough, all is well and good, but a filter is then needed to cut off any frequencies above, say, 150 Hz. Often, a subwoofer network is an active filter, but here this would necessitate an additional power supply. The present network is a passive one, designed so that the speaker signal of the existing system can be used as the input signal. Crossover For Subwoofer Circuit diagram : -  Crossover Circuit Diagram For Subwoofer Since the bass information is present in both (stereo) loudspeakers, the signal for the sub woofer can simply be tapped from one of them. The network is a 1st order low-pass filter with variable input (P1) and presettable cut-off frequency (P2). The signal from the loudspeaker is applied to terminal ‘LSP’. Volta...

This is a very simple circuit of a bio-stimulator Muscular, which has indications for the treatment of cellulite. He sends little shocks through two electrodes, and should take great care when using the stimulator. The muscle stimulator circuit is based on a 555 timer IC. The transformer must be 220 volts to 12 100 to 150 mA and the circuit is connected in reverse. Muscular Bio-Stimulator for Treatment of Cellulite Circuit Diagram The IC 555 to generate pulses at 80 Hz and 150usec by the output voltage of the muscle stimulator device is about 60 volts to 150 volts, but the output current is very small and there is no danger of electric shock. The potentiometer P1 bio-stimulator sets the amplitude of the output pulses' and must be operated by the "patient", starting with the knob fully counterclockwise, then rotating it slowly clockwise until the LED begins to light up. The functional principles of the bio-stimulator is the same commercial bio-stimulator. Parts List: Linea...

The title refers to a popular TV game show where the contestants each have a big button.  The  game show  host  asks  a  question and the first contestant to press their but-ton makes an illuminated indicator light up on their desk. The other contestants’ buttons  are automatically inhibited, so that everyone can see who was the first contestant to press their button, and so is allowed to answer the question. The project described here shows how to build a similar sortof  refereeing device yourself, using simple resources and without needing a microcontroller, which is  pretty rare these days! The basic circuit is for  just two contestants, but the modular design  means it can easily be expanded.   Circuit diagram :   Going for Gold Circuit Diagram   The diagram shows three buttons: S2 and S3  are the buttons for the two contestants, S1 is  the button for the host, which allows them to  reset the circuit before each fresh question.  The ‘brains’ of the circuit is IC1, a 4013 du...

This is a Simple Step-Up Converter For 20 LEDs circuit Project. The circuit described here is a step-up converter to drive 20 LEDs, designed to be used as a home-made ceiling night light for a child’s bedroom. This kind of night light generally consists of a chain of Christmas tree lights with 20 bulbs each consuming 1 W, for a total power of 20 W. Here, in the interests of saving power and extending operating life, we update the idea with this simple circuit using LEDs.  Power can be obtained from an unregulated 12 V mains adaptor, as long as it can deliver at least about 330 mA.  The circuit uses a low-cost current-mode controller type UCC3800N, reconfigured into voltage mode to create a step-up converter with simple compensation. By changing the external components the circuit can easily be modified for other applications. To use a current-mode controller as a voltage-mode controller it is necessary to couple a sawtooth ramp (rising from 0 V to 0.9 V) to the CS (current sen...

This instructable shows how to wire up one or more LEDs in a in a basic and clear way. Never done any work before with LEDs and don’t know how to use them? If you have wired up LEDs before, this explanation might seem overly simplistic. Consider yourself warned. [ ]