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In this schematic circuit is presented a very simple Zener Diode Tester circuit that require few external components to  be build . Zener Diode Tester Circuit diagram As you can see in the schematic circuit , the Zener Tester  project is based on a common 741 operational amplifier .The supply need only be as high a value as the zener itself . The variable resistor P can be calibrated ( in volts ) , so when the LED 1 lights the voltage on pins 2 and 3 of the 741 operational amplifier is nearly equal .

This is a Simple Project of Passive Sub woofer filter Circuit Diagram . This circuit not required power supply because is a simple low frequency passive filter. It could be useful if you want to drive an extra sub-woofer from your stereo system.  Passive Sub woofer filter Circuit Diagram The circuit filters the frequency ranges above the 150Hz. The schematic is calculated to work with a 50 watts audio amplifier, but can be used with higher powers as well. The frequency can be adjusted with 2k2 potentiometer from 50 Hz to 160 Hz.

Simple Tone Control Circuit Diagram TDA2030 . This is a best tone circuit with TDA2030, Tone controls include Bass, Treebel, and Volume. Power amplifier and tone control has been put together in a single PCB. As well as its power supply circuit was also used as one with the power amp, and tone control. Making it easier in the installation and will look neat.  Simple Tone Control Circuit Diagram PCB Layout    PCB Design This amplifier is a mono amplifier type, can be modif for guitar amplifiers. If not coupled amplifier (mic preamp) then you must deactivated potensio treble and bass, why? because if not using a mic preamp and still maintain potensio treble and bass sound input (input) from the guitar will not or the maximum discharge is not tight on the speakers. So you must deactivated a way to decide which directly connected capacitor with the tone control circuit, and capacitor were connected directly to potensio volume and input jack.

It is very low-cost and simple electronic circuit project for temperature controller using the LM3911 highly accurate temperature measurement and control system designed in a single monolithic chip. The output voltage of the LM3911 is directly proportional to temperature in degrees Kelvin at 10 mV/degree K. As you can see in this circuit diagram, LM3911 temperature sensor chip require few additional components. Temperature Controller Circuit Diagram:   The resistor network consists of R1, R2, and R3 is used to provide the set point voltage reference for the feedback input of the LM3911. R4 resistor is used to limit the current through the internal voltage reference of the LM3911. R5 resistor pulls the output of the IC high when the temperature is bellow the set point. The internal resistor is in series with a diode that allows a switching voltage up to 35 volts to be used. By modifying the R2 variable potentiometer you will modify the set point of the temperature controller. This simpl

VCT4942 – 24C161 – LA42032 – LA78045 – FSCQ0765RTS(STR) – FQP6301TSTU(Horizontal output transistor) – FOK14B001(FBT)  CRT base card Side AV SMPS and deflection Syscon-Chroma Click on the schematics to zoom in

I have a circuit where I want to have a constant current of 2mA through a variable resistor. I've been told that I could probably use a LM317 as a current regulator, with one resistor on the ouput. But I've read some places that the LM317 takes minimum 5-10mA load to function correctly. How can I achieve a constant current output of 2mA when I don't know the resistance of the variable resistor? The input voltage is about 2.755V. Output voltage doesn't matter, just the current. Here's an image to my feeble attempt at a schematic: The LM317 with the single series resistor between output and adjust input is actually a fixed current source, not a current limiter. You don't need the LM317 to create a current limiter, a few discrete components will do: For a limiting at 2mA you select a 330 Ω resistor for R S E N S E . If there flows 2mA through it Q2 will start to conduct and reduce the base voltage of Q1, so that its current is cut off. edit (re changed question)

0,5 WATT MINI AMPLIFIER TDA1015T ELECTRONIC DIAGRAM Chances are you'll want this amplifier portable. Batteries do the trick fine, but you won't get much power out of a couple of 1.5V cells. Unfortunately the size of a decent amount of battery power will mean that the overall size of this amp will be much bigger and for that there are more benefits to be had using a device like the TDA7052 or TDA2822 for stereo. Quick ref data of TDA1015T Chip     Supply voltage range: 3,6 to 12 V     Peak output current: 1 A     Output power: 0,5 W     Voltage gain power amplifier: 29 dB     Voltage gain preamplifier: 23 dB     Total quiescent current: 22 mA     Operating ambient temperature range: -25 to +150 °C     Storage temperature range: -55 to + 150 °C

 At this point is a Solar Charger Circuit to is used to charge information Acid otherwise Ni-album batteries using the solar energy power. The circuit harvests solar energy to charge a 6 volt 4.5 Ah rechargeable battery in favor of various applications. The stallion has Voltage and Current supervision and terminated voltage restrict sour facilities. Circuit uses a 12 volt solar panel and a changeable voltage supervisor IC LM 317 . The solar panel consists of solar cells each one rated on 1.2 volts. 12 volt DC is presented from the panel to charge the battery. Charging current passes through D1 to the voltage watchdog IC LM 317. By adjusting its Adjust pin, output voltage and current can subsist regulated. VR is placed amid the adjust pin and ground to provide an output voltage of 9 volts to the battery. Resistor R3 confine the charging current and diode D2 prevents discharge of current from the battery. Transistor T1 and Zener diode ZD conduct yourself having the status of a stop rott

Battery-life measurement for a portable system is a time-consuming task and many methods used for it do not give reliable results. Presented here is a circuit using which you can measure the battery-life very easily. Here, an analogue clock tracks the discharge time of the battery used in battery-powered portable devices. Circuit and working The circuit for battery-discharge measurement is shown in Fig. 1. It is built using low-power single-/dual-supply comparator MAX921 (IC1), MOSFET VN0300L (IRF1), an analogue clock and a few other components. IC1 monitors the life of the BUT (battery under test) and controls the power supply for the analogue clock. When the BUT voltage falls below the threshold value set by VR1, IC1’s output becomes low, which turns off MOSFET IRF1. This means, power supply for the analogue clock is cut off and so the clock stops running. The reading on the clock at this point gives the discharge time of the BUT, provided you had set the clock to 12:00 before testin

Using two op amps, this filter is designed for second-order response. It has a bandpass of 300 to 3400 Hz, for applications in speech or telephone work. 300-3400 Hz Second Order Speech Filter Schematic 

Here is a circuit 120 watt stereo amplifier using STK4241V . The MAX9710 a stereo audio power amplifier capable of delivering 2 x 120 W of the IC to put loads of 8 ohms. MAX9710 can be operated from ± 32V single power supply of ± 54V. This amplifier circuit is ideal for audio devices for home supply. STK4241V amplifier specifications might lead one to believe that you can use supply voltages of ± 78V. With zero input signal (and therefore no way out) I could, but I would not recommend anything better than ± 45V 8-ohm loads, if expected, although ± 54V will be fine if you can provide a good heat sink.

A simple electric motor homemade, easy to make. 1. 1 meter of wire 2. magnet 3. one battery AA or AAA 4. Improvisation

Stroboscope is a device used to make a cyclically moving object appear slow-moving or stationary. This is realised by illuminating the object intermittently with short pulses of light. Stroboscope is used in the study of insect flight. It can also be used for experiments with simple pendulum, studying details of rapidly moving objects and strobo-animation. Here is the circuit of a stroboscope that produces dual-coloured light pulses (refer Fig.1). The circuit uses red and green LEDs as light sources to illuminate the object. You can choose the frequency of the stroboscope’s light pulses from a wide range of 5 Hz to 5 kHz as desired. The range of frequency (5-50 Hz, 50-500 Hz, 500 Hz-5 kHz, etc) is selected through capacitors Ca (C2, C3 and C4), Cb (C5, C6 and C7) and Cc (C8, C9 and C10). Circuit diagram : Dual-Colour Stroboscope Circuit Diagram Smooth variation of the frequency range is achieved by varying VR1. The length of the light pulses (both red and green pulses are of equa

Car Stereo Speaker: Let Your Car Stereo Speak For Itself - Even if you’re not a car audio connoisseur, it’s easy to be impressed with a car stereo speaker while looking around in an expo or convention. They’re the first thing you’ll probably notice, they come in different colors, shapes and sizes. Those big throbbing concaves blaring incredibly low bass lines or cool little tweeters whistling out seething treble sounds. Car stereo speakers are interesting and very tempting to buy, especially the big loud ones. But big is not always the best. Each speaker has its own unique quality, intended use and price range. Some may also be better than others at certain things so it pays to investigate your type of car stereo amplifier or head unit before you finally decide on a car stereo speaker for your system. Here are some features to consider:  Car stereo speakers are not all the same size and wattage, and this can cause a problem once you try to hook it up in your car. Know the specs of your

This 16 LED Chaser Circuit Diagram is a double direction flash. Similar to Digital Ping- Pong 1, there is a movement of a lit dot, up and down along the LED's length. 16 LED Chaser Circuit Diagram When the D16 lit the situation changes and there is a reverse movement. Lit D15-14 ……D16, is lit making circles when the circuit is under power. The IC1 is an unstable flip- flop supplying with stable frequency pulses (the frequency can be changed by TR1, adjusting the velocity of the LED's up and down). This frequency supplies the IC3 (which is a 4-Bit UP and DOWN counter) through 2 gates A-B of the IC2. The output counter supplies the IC4 that is the driver of the LED's. The parts C- D of The IC2, make a R-S flip- flop, that changes situation, when the edge LED's D1 and D16 lit. We have an electronic limit for the situation change. In proportion the shape we make with the LED's, we can have the proportionate optional result, making various effects. Part List R1= 100Kohm

  As is always the case with a two-way active monitor, each B2031 is equipped with two separate power amplifiers – one for the low frequency driver and one for the tweeter (150 watts and 75 watts respectively).  The low frequency polycarbonate driver is 22cm in diameter and the high frequency duties are handled by a one-inch ferofluid-cooled titanium dome tweeter. The crossover circuitry consists of an active fourth-order witz-Riley filter kicking in at 2kHz. The enclosure also employs a bass reflex porting system to extend the low frequency drivers’ overall frequency response down to a quoted 50Hz.  Other features of the B2031s worthy of note include: protection circuitry to look after the drivers and amplifiers in the event of overload; and electromagnetic shielding to allow close placement of the B2031’s to TV screens and computer monitors without interference. At the back of the B2031s you’ll find a metal amplifier housing which extends about an inch or so beyond the dimensions of

This DC adaptor provides a regulated 9V source for operating a transceiver in the car .The IC LM317 is mpounting tab is electrically connected to its output pin. so take this into account tour version of the adapter. The LM317T regulator dissipates 2 or 3 Watt in this circuit , so mount it on a 1- x -2 inch piece of 1/8 inch thick alumunium heatsink. Dont forget to give heatsink on the IC LM317.

Most of the time, in a cartoon or in a movie, whenever the character experiences an “Eureka!” moment, a light bulb would just appear on the head. Well, just in case your boss thinks that you are the dimmest bulb in the office, prove him or her wrong by picking up the £10.99 Bright Idea USB Lightbulb.     Yes sir, I think you do know just which direction I am heading with this – it is the perfect desk accessory which lets the world around you know just how many brilliant thoughts you would have come up with throughout the eight hours at the desk! Located right at the end of a sturdy and flexible arm, lies the Bright Idea USB Lightbulb which happens to be a fuss-free lamp, sans switches, where it will also not come with a lampshade nor any legs. No sir, it is up to that creative mind of yours to concentrate and deliberate over grand ideas. ou will find it emit a soft and soothing blue light as long as it remains plugged into any USB port, where it will shine some reassuring illumination

This is the project of simple Period To Voltage Converter Circuit Diagram . The input signal drives ICD. Because ICD`s positive input (V+) is slightly offset to + 0.1 V, its steady state output will be around +13 V. This voltage is sent to ICC through D2, setting ICC`s output to +13 V. Therefore, point D is cut off by Dl, and CI is charged by the current source.  Assuming the initial voltage on CI is zero, the maximum voltage (^Cinax) is given by: When the input goes from low to high, a narrow positive pulse is generated at point A. This pulse becomes -13 V at point B, which cuts off D2. ICC`s V+ voltage becomes zero.  Period To Voltage Converter Circuit Diagram The charge on CI will be absorbed by ICC on in a short time. The time constant of C2 and R5 determines the discharge period— about 10 /is. ICB is a buffer whose gain is equal to (R& + R9)~Rg = lM5. ICD`s average voltage will be (1362f 1.545) + 2 = 1052/. RIO and C3 smooth the sawtooth waveform to a dc output.

This is the Simple Water-level indicator Circuit Diagram. n this a warning device WD1 is in series with SCR1. When the liquid level causes a conductive path between the probes, the SCR conducts sounding WD1. The warning device may be a Sonalert (TM), a lamp or a buzzer.D1 acts as a transient suppressor. Press SI to reset the circuit. Simple Water-level indicator Circuit Diagram

This is a simple 12 V Battery Charger Circuit Diagram is a high performance charger for gelled electrolyte lead-acid batteries. Charger quickly recharges battery and shuts off at full charge. Initially, charging current is limited to 2A. As the battery voltage rises, current to the battery decreases, and when the current has decreased to 150 mA, the charger switches to a lower float voltage preventing overcharge.  12 V Battery Charger Circuit Diagram When the start switch is pushed, the output of the charger goes to 14 V. As the battery approaches full charge, the charging current decreases and the output voltage is reduced from 14 V to about 12 5 V terminating the charging. Transistor Ql then lights the LED as a visual indication of full charge.

This acoustic sensor was originally developed for an industrial application (monitoring a siren), but will also find many domestic applications. Note that the sensor is designed with safety of operation as the top priority: this means that if it fails then in the worst-case scenario it will not itself generate a false indication that a sound is detected. Also, the sensor connections are protected against polarity reversal and short-circuits. The supply voltage of 24 V is suitable for industrial use, and the output of the sensor swings over the supply voltage range. Circuit diagram : Simple Acoustic Sensor Circuit Diagram The circuit consists of an electret micro-phone, an amplifier, attenuator, rectifier and a switching stage. MIC1 is supplied with a current of 1 mA by R9. T1 amplifies the signal, decoupled from the supply by C1, to about 1 Vpp. R7 sets the collector current of T1 to a maximum of 0.5 mA. The operating point is set by feedback resistor R8. The sensitivity of the circui

Low cost fire alarm circuit. Description. W hen there is a fire breakout in the room the temperature increases. This ultra compact and low cost fire alarm senses fire breakout based on this fact. Transistor BC177 (Q1) is used as the fire sensor here. When the temperature increases the leakage current of this transistor also increases. The circuit is designed so that when there is an increase in the leakage current of Q1, transistor Q2 will get biased. As a result when there is a fire breakout the transistor Q2 will be on. The emitter of Q2 (BC 108) is connected to the base of Q3(AC 128). So when Q2 is ON Q3 will be also ON. The transistor Q3 drives the relay which is used to drive the load ie,light,bell,horn etc as an indication of the fire. The diode D1 is used as a free wheeling diode to protect it from back EMF generated when relay is switched. Low cost fire alarm circuit. admin April - 19 - 2008 85 Comments Description. W hen there is a fire breakout in the room the tempe

RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM This circuit produces oscillating frequency around 1kHz, and able to be converted by changing the value of resistor R1. The speaker will produce a long beep sound with 1kHz frequency. Here is the schematic : Parts list :     Resistor R1 : 10k ohm     Resistor R2 : 56k ohm     Capacitor C1-C2 : 0.01 uF     Polar capacitor C3 : 1 uF/15V     IC timer : NE 555     Speaker : 8 ohm 0.5 W     ON/OFF switch     5-15V Power supply

Antennas are much shorter than quarter wavelength impedance obtained is very small and highly dependent on the frequency. It was a difficult game impedances over a decade of frequency coverage. Instead, the phase of the input source-follower FET Q1. A high impedance input successfully bridges Antenna characteristics at any frequency. 1/4 wavelength Active Antenna Circuit Diagram   transistor Q2 is used as a follower, to provide a high impedance load for Q1, but more importantly that it makes to drive low-impedance amplifier coupled to commonly Q3, which each receive a voltage amplifier. Q3 Q4 turns transistor output impedance is relatively low in impedance, which is enough to drive 50 Three dimensional receiver, Antenna input impedance.

Advantages and Disadvantages of Moving Iron Instruments Advantages 1.        The instrument can be used both on DC as well as on AC circuits. 2.        These instruments are cheap, robust and simple in construction. 3.        The instruments have high operating torque. 4.        The instruments are reasonably accurate. 5.        These instruments can withstand overload momentarily. Disadvantages 1.        Scales of these instruments are not uniform because of pneumatic damping. 2.        Errors are introduced due to change of frequency I case of A.C. 3.        Errors are introduce due to hysteresis and stray magnetic field. 4.        Power consumption is high.

79xx is a widely known series of low-cost, fixed-negative-voltage regulators. These integrated circuits are available with output current of 100-150 mA (L series), 0.4-0.5A (M series), up to 1A (standard series), etc. They can be used in many applications other than regulators, audio power amplifier being one of them.  As shown in the circuit diagram, a simple stereo audio amplifier is built around two 7905 negative-voltage regulators (IC1 and IC2) and a few discrete components. The 7905 IC (a -5V regulator) used here is readily available. However, the circuit will also work with other 79XX regulators if appropriate power supply is used. Both channels shown in the diagram are identical. Hence the description below is only for the first channel. The quality of the output signal is within acceptable limits. Stereo Power Amplifier Using IC 7905 Circuit diagram : . Stereo Power Amplifier Circuit Diagram   Regulator IC 7905 works as an amplifier for the voltages applied to common pin2 (Gr

Class one Headphone Amplifier Circuit diagram. This circuit is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability. Class one Headphone Amplifier Circuit diagram : Class-A Headphone Amplifier Circuit diagram The above mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble li

A notch for a narrow frequency band of a few per cent or even less normally requires close-tolerance components. At least, that’s what we thought until we came across a special opamp IC from Maxim. In filters with steep slopes, the component tolerances will interact in the complex frequency response. This effect rules out the use of standard tolerance components if any useful result is to be achieved. The circuit shown here relocates the issue of the value-sensitive resistors that determine the filter response from ‘visible’ resistors to ready available integrated circuits which also make the PCB layout for the filter much simpler. The operational amplifiers we’ve in mind contain laser-trimmed resistors that maintain their nominal value within 1‰ or less. For the same accuracy, the effort that goes into matching individual precision resistors would be far more costly and time consuming. The desired notch (rejection) frequency is easily calculated for both R-C sections shown in Figure 1.

Description An increasing number of appliances draw a very small current from the power supply. If you need to design a mains powered device, you could generally choose between a linear and a switch-mode power supply. However, what if the appliance’s total power consumption is very small? Transformer-based power supplies are bulky, while the switchers are generally made to provide greater current output, with a significant increase in complexity, problems involving PCB layout and, inherently, reduced reliability.  Is it possible to create a simple, minimum part-count mains (230 VAC primary) power supply, without transformers or coils, capable of delivering about 100 mA at, say, 5 V A general approach could be to employ a highly inefficient stabilizer that would rectify AC and, utilizing a zener diode to provide a 5.1 V output, dissipate all the excess from 5.1 V to (230×v2) volts in a resistor. Even if the load would require only about 10 mA, the loss would be approximately 3 watts, so

This is the Cheap and Simple Gate Alarm Circuit Diagram. A cheap and simple gate alarm made from a single CMOS Integrated Circuit.    Cheap and Simple Gate Alarm Circuit Diagram Circuit Notes Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply. IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The circuit is intended not so much to sound like a siren or warning device, but rather to give the impression: "You have been noticed." R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted. IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: "I'm more clever than a simple on-off devic

‘Valve sound’ is not just an anachronism: there are those who remain ardent lovers of the quality of sound produced by a valve amplifier. However, not everyone is inclined to splash out on an expensive valve output stage or complete amplifier with a comparatively low power output. Also, for all their aesthetic qualities, modern valve amplifiers burn up (in the full sense of the word!) quite a few watts even at normal listening volume, and so are not exactly environmentally harmless. This valve sound converter offers a cunning way out of this dilemma. It is a low cost unit that can be easily slipped into the audio chain at a suitable point and it only consumes a modest amount of energy. . Valve Sound Converter Circuit Diagram A valve sound converter can be constructed using a common-or-garden small-signal amplifier using a readily-available triode. Compared to using a pentode, this simplifies the circuit and, thanks to its less linear characteristic, offers even more valve sound. For