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The circuit has been designed to provide an alarm with the use of a buzzer when sensing high temperature by using a thermistor. Thermistor – one type of resistor used as temperature-sensing element which demonstrates a large change in resistance proportional to a small change in temperature because of the composition of its semiconductor material. BC550 – an NPN general purpose transistor with low current and low voltage used for low noise stages in audio frequency equipment. The temperature can be regulated by the design of this circuit and it can provide a warning scheme in the case of excessive increase in the temperature. The control of the temperature starts from the thermistor TH1 which contains a negative factor. Since this component has resistance proportional to the temperature that it detects, the resistance can be modified wherein a 10K ohm resistance is produced ate 25° C while 1K ohm resistance will be produced at 94° C. to define a specific value of temperature, a trimmer...

This high quality and low cost speaker was designed to be used for iPod or iPhone with the use of old car Hi-Fi speaker and some computer components. Other materials used are shown in the image below and they include an amplifier, 240V-12V power supply, tweeters, crossovers, sealed lead acid battery, MDF, filler, Apple universal dock & remote, glue, nails, and white gloss paint. The front baffle board was drawn on a piece of MDF in order to use it as a template to make the rear of the box. The dimensions of the box based on the speaker do not necessarily need to be exact because the speakers were quite old as it comes from an old Renault 19. From the photo of the round bits below, the trusty circular saw was used to cut loads of 1 inch by 15 cm strips of MDF. Between the front and rear baffle, the strips were glued and nailed. The baffles were cut out using a jigsaw and the strips were kept as close to each other as possible. The first coat of filler can take 3 batches to finish an...

In this series of essentially the same principle with the power supply, but power supply is working to produce high voltage. And high voltage which is regulated by this series becomes more filtered and either used for electronic devices that are not easily damaged. High Voltage regulator schematics Component List R1_____________1K R2_____________470K R3_____________330K R4_____________20K C1_____________39uF 450V C2_____________39uF 450V C3_____________39uF 450V C4_____________39uF 450V C5_____________10uF 25V C6_____________220nF 250V C7_____________100nF 400V D1_____________1N4007 D2_____________1N4007 D3_____________1N4007 D4_____________1N4007 D5_____________1N4148 D6_____________1N4148 TR1____________MJE13005 TR2____________MPSA92 TR3____________MPSA42

This circuit is of an 2x 2,500W RMS stereo amplifier, super-light and without switching-mode power supply. The circuit just shows a channel, and the power supply that it assists to the two channels. The audio circuit should be duplicated, but the power supply assists to the two channels without problems. A special care should be destined to the insulating transformer of the audio line, that should be of audio-high-quality, of the type used in microphone pre amps input line. The whole group (2 channels) of 5,000W RMS it should not weigh more than 32 lbs, already inside of an appropriate metallic box. Warning This circuit is exclusively for amateur use. It contains not-isolated parts of the electric AC net and it can be very dangerous. The connections for the speakers are not isolated of the domestic AC net and it requests extra care. This procedure seeks to substitute a conventional power supply with great weight and cost reduction, without necessarily to use a switching-mode power supp...

Occasionally you come across some unusual  situations when setting up measurement  systems. The author once had to set up a system to register the vibrations and strain supposed to be  present in a contactor that operated at a voltage of 25 kVAC. One of the biggest problems with this project turned out to be the power supply for  the measurement system. Since it required  a power of about 30 W it wasn’t possible to  use batteries since the system had to operate  for many hours at a time. A logical solution  would seem to be to use an isolating trans-former, but still.25 kVAC means a peak volt-age approaching 40 kV, and on top of that  you would have to include a safety margin. In  addition, everything that is connected to high  voltage lines should also be able to withstand  lighting strikes! Circuit diagram : Power Supply with High Voltage Isolation Circuit Diagram Consequently the isolation should be able to  cope wit...

Here’s a project that could be useful this summer on the beach, to stop anyone touching your things left on your beach towel while you’ve gone swimming; you might equally well use it at the office or workshop when you go back to work. In a very small space, and powered by simple primary cells or rechargeable batteries, the proposed circuit generates a low-energy, high voltage of the order of around 200 to 400 V, harmless to humans, of course, but still able to give a quite nasty ‘poke’ to anyone who touches it. Quite apart from this practical aspect, this project will also prove instructional for younger hobbyists, enabling them to discover a circuit that all the ‘oldies’ who’ve worked in radio, and having enjoyed valve technology in particular, are bound to be familiar with. As the circuit diagram shows, the project is extremely simple, as it contains only a single active element, and then it’s only a fairly ordinary transistor. As shown here, it operates as a low-frequency oscillator...

High Power Audio Amplifier 2800W, Mono power amplifier ouput is 1400Watt / channel. and this circuit is mono power amplifier circuit . See schematic :  Click schematic to view larger See description at source link page Source : High Power Amplifier 2800W

This is smart High Voltage Power Supply 10kV Circuit Diagram. Be very carefull with this power supply because uses 220V mains and has 10KV at output. Characteristics: supply: 220V AC 50Hz mains Power: 15 Watts Ignition Voltage: 8KV . High Voltage Power Supply 10kV Circuit Diagram Sourced By: Circuitsstream

The hobby circuit below uses an unusual method to generate about 12,000 volts with about 5uA of current. Two SCRs form two pulse generator circuits. The two SCRs discharge a 0.047uF a 400v capacitor through a xenon lamp trigger coil at 120 times a second.  12KV High Voltage Generator Circuit Diagram The high voltage pulses produced at the secondary of the trigger coil are rectified using two 6KV damper diodes. The voltage doubler circuit at the secondary of the trigger coil charges up two high voltage disc capacitors up to about 12KV. Although this circuit can’t produce a lot of current be very careful with it. A 12KV spark can jump about 0.75 of an inch so the electronic circuit needs to be carefully wired with lots of space between components. Source: DiscoverCircuits

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 amplifier that can run from a 12V battery. It could be just the ticket for buskers who want a small but gutsy amplifier which will run from an SLA battery or it could used anywhere that 12V DC is available – in cars, recreational vehicles, remote houses with 12V DC power or where ever. 20W Stereo Audio Amplifier Because it runs from DC, it will be an ideal beginner’s or schoolie’s project, with no 240VAC power supply to worry about. You can run it from a 12V battery or a DC plugpack. But while it may be compact and simple to build, there is no need to apologise for “just average” pe...

This white LED Driver circuit project is based on the NCP5680 high efficiency white LED Driver ic. NCP5680 supports double power flash LED and torch operation . The built-in DC/DC converter is based on a high efficient charge pump structure with 1X, 1.5X and 2X operating modes. The NCP5680 controller is designed to properly drives large external NMOS device with accurate control of the peak current flowing into the LED. Also, the NCP5680 chip includes Open Load and Overload Detection circuit to protect the system against faults at Vout or LED level. High Efficiency White LED Driver Circuit diagram Main features of the NCP5680 are : 2.7 to 5.5 V Input Voltage Range , Dual Power Flash LED Capability , Integrated Overload Protection , Selectable Flash/Torch Mode of Operation , Programmable SuperCAP Re−cycling Current , Capable to Share the DC Voltage to Supply Peripheral Circuits , Indicator LED Function , Integrated Photo Sense Function , Support Camera Strobe , Built−in Short Circuit Pr...

Spesification of this amplifier is high enough , and require a lot of expense to make this super-power amplifier. In the transformer using 20A and manufactered / branded ERA , ERA trafo is one of the best transformer , in addition to the power amplifier as well as power supply adapter , regulator , stabilizer , charger , etc. Because copper is intact , a strong iron and did not issue a frequency so that when the amplifier is turned on , output sound amplifier no buzzing. So if you in choosing a transformer , do not hesitate to use the transformer branded ERA.   Above and below the picture is the end of the amplifier circuit, so-called booster amplifier. Picture above using 14 pairs of transistor MJ15025G and his partner MJ15024G . Transistor price range of $5 - $6 , has power output of 250W on each transistor , for more details , see datasheet of each transistor. Click to view larger Installed transistor with resistor but still a mess Transistors MJ5025G and MJ15024G very fith with...

This Electronic Circuit Project of high voltage generator circuit. This high voltage generator was designed  with the aim of testing the electrical break-down protection used on the railways. These  protection measures are used to ensure that  any external metal parts will never be at a  high voltage. If that were about to happen,  a very large current would flow (in the order  of kilo-amps), which causes the protection  to operate, creating a short circuit to ground effectively earthing the metal parts. This hap-pens when, for example, a lightning strike hits  the overhead line (or their supports) on the  railways. This generator generates a high voltage of  1,000 V, but with an output current that is limited to few milliamps. This permits the electrical breakdown protection to be tested with-out it going into a short circuit state. The circuit uses common parts throughout: a  TL494 pulse-width modulator, several FETs or  bipo...

This audio amplifier designed uses two LM3886 per channel, in parallel circuit, based on the PA100 parallel amplifier detailed in National Semiconductor's application note - AN1192. This amplifier can deliver about 50W into a 8-ohm speaker and 100W into a 4-ohm speaker. This is a stereo amplifier and therefore 4 LM3886s are used. The LM3886 circuit is in a non-inverted configuration, so the input impedance is determined by the input resistor R1, i.e. 47k. The 680 ohm and 470pF resistor capacitor filter network is used to filter out the high frequency noise at the RCA input. The 220pF C4 and C8 capacitors are used to shot out the high frequency noise at the LM3886 input pins. I used high quality audio grade capacitors at several locations: 1uF Auricap at the input for DC blocking, 100uF Blackgate for C2 and C6, and 1000uF Blackgate at the supply filter. LM3886 Power Amplifier Schematics The PCB is designed in a way that the power ground is separated from the signal ground, as you ca...

High Gain Crystal Earphone Amplifier This simple, one-transistor amplifier provides a voltage accretion over 1000 (60 dB) for active a aerial impedance bowl (crystal) earphone. The aerial accretion is accomplished by replacing the acceptable beneficiary resistor with an abnormal constant-current diode that food 1/2 mA yet exhibits a actual aerial attrition to the audio. This amplifier will accord accomplished array life, cartoon alone 500 uA. Below is a archetypal appliance application it with the aboriginal clear radio ambit on this page. The amplifier provides acceptable aggregate with a bashful antenna. You may appetite a aggregate ascendancy as with the TL431 project! Or use the Crystal Radio RF Amplifier directly above for even more sensitivity with less than 2 mA current drain.

Dual High Side Switch Controller Circuit diagram : Dual High Side Switch Controller Circuit Diagram One of the most frequent uses of n-channel MOSFET’s is as a voltage controlled switch. To ensure that the MOSFET delivers the full supply voltage to the load it is necessary for the gate voltage to be a few volts above the supply voltage level. This can be a problem if no other suitable higher volt-age sources are available for use elsewhere in the circuit. The LTC 1982 dual high-side switch controller from Lin-ear Technology (www.linear-tech.com) solves this problem by incorporating a voltage tripler circuit in the gate driver stage. The gate voltage is limited to +7.5 V which is 2.0 V above the IC’s maximum operating voltage. It can directly drive the gate of logic-level MOSFET with a VGS(th) from 1.0 V to 2.0 V. A suitable n-channel logic level MOSFET would be the BSP 295. This device can switch up to 1.5 A and is available in an SOT 233 SMD package.

The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged. The under/over voltage protection circuit with time delay presented here is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which the voltage is beyond limits) is less than the delay time, the power resumes after the delay: If it is equal or more, then the power resumes directly. This circuit has been desig...

The circuit described here is based on the superior characteristics of dual-gate MOSFET (metal-oxide semiconductor field-effect transistor). It exhibits a very high input impedance that lends for good sensitivity and very less loading of the input signal source. Low cross-modulation characteristic leads to minimal distortion of the output with respect to the input signals. Also, the MOSFET offers low feedback capacitance and high transconductance. All these advantages make the MOSFET the most effective for high-quality mixer and converter applications. This dual-input audio frequency mixer circuit employs a single dual-gate MOSFET 3N200. One may, however, substitute it with any other dual-gate.  MOSFET such as 3N187 and BF966. (It is to be noted that BF966 is not gateprotected and hence calls for suitable precaution in handling it.) The audio frequency (AF) input from the first channel (CH1) is applied on gate 1 (G1) of the MOSFET through 500- kilo-ohm potentiometer VR1. The AF input f...

Circuit Diagram Description The heart of the circuit is TDA7294 which acts as an amplifier the right and left input feded from the pre amplifier circuit is amplified after passing through the noise filter which contains an RC circuit, the volume is controlled by the variable resistor 47k. and the automatic gain control is provided by the operational amplifier circuit opp amp IC249 For both right channel and left channel., the speaker used is an 8 ohms 40 watts speaker.  Source -http://www.electronguide.com/circuits_pages/AudioAmplifier.html

The hobby circuit below uses an unusual method to generate about 12,000 volts with about 5uA of current. Two SCRs form two pulse generator circuits. The two SCRs discharge a 0.047uF a 400v capacitor through a xenon lamp trigger coil at 120 times a second. 12KV High Voltage Generator Circuit Diagram The high voltage pulses produced at the secondary of the trigger coil are rectified using two 6KV damper diodes. The voltage doubler circuit at the secondary of the trigger coil charges up two high voltage disc capacitors up to about 12KV. Although this circuit can’t produce a lot of current be very careful with it. A 12KV spark can jump about 0.75 of an inch so the electronic circuit needs to be carefully wired with lots of space between components.