TREE

Usually, Low-Cost Stereo Level Indicator home stereo power amplifiers don’t have output level indicators . An output power level indicator can be added to each channel of these stereo power amplifiers . As low levels of the output power are not disturbing and damaging to the people, there is no need to add a preamplifier and low-level detector before IC LM3915. But you should know when the output power becomes considerably high. Here we present a very simple, low-cost stereo-level indicator circuit for home power amplifiers with power rating of around 0.5W. The circuit is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display. Stereo Level Indicator Circuit Diagram The voltage levels below 1V are not important because these correspond to a low level of the audio signal. Similarly, input voltage levels above 30V correspond to too high levels of the output power, which ...

This is a simple power on switching circuit . This type of reset pulse is ideally provided by this circuit. Because of the high input impedance of the Schmidt trigger, long reset pulse times may be achieved without the excess dissipation that results when both output devices are on simultaneously, as in an ordinary gate device (B). A reset pulse is often required at power-on in a digital system. See circuit diagram below. Simple Power On Reset Circuit Diagram

Build 32 Watt Amplifier Circuit Using by TDA2050V. A 32 Watt per channel stereo power amplifier made using the TDA2050V monolithic integrated circuit.  32 Watt Amplifier Circuit Diagram Notes: This circuit is for a 32 Watt stereo audio power amplifier using the TDA20501. With a dual 22 Volt supply this amplifier can deliver 32W into 8 ohm loudspeakers. Moreover, the TDA 2050 delivers typically 50W music power into 4 ohm load over 1 sec at VS= 22.5V and f = 1KHz. The amplifier is cased as a Pentawatt package see pinout below: This is a power amplifier and requires 200mV RMS for full output. Voltage gain is 30.5dB with resistor values shown. Closed loop gain is set by Ratio R1/R2. Increase R2 for less gain and vice versa. Power bandwidth is 20Hz to 80KHz. R3, C3 and R6, C11 form a zobel network to prevent high frequency instability. The speaker is direct coupled, therefore no expensive large value electrolytics are needed and the bass will be crisp and clean. It is advisable to plac...

Description: This circuit takes an ordinary loudspeaker and allows it to be used in reverse, as a microphone. Circuit diagram Notes: This circuits allows you to use a cheap loudspeaker as a microphone.Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speakers magnetic field will produce a small electrical signal . The circuit is designed to be used with an operating voltage between 6 and 12 volts dc. The first transistor operates in common base mode. This has the advantage of matching the low input impedance of the speaker to the common base stage, and secondly has a high voltage gain. The second stage is direct coupled and operates in emitter follower. Voltage gain is slightly less than unity, but output impedance is low, and will drive long cables. Speech quality is not as good compared to an ordinary or ECM microphone, but quite acceptable results can be obtained. Speaker cones with diameters of 1 inch to 3 inches may be used....

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. Toggle Touch Switch Using Two Inverter Gates Circuit Diagram If we touch the pad at this condition, where the output is high, then the U1A input will go high because we “short” the voltage of C1 to the input pin, and the low level previously caused by low level of U1B output voltage connected via R2 can’t be maintained because our skin resistance is much lower than 10M. After U1A input goes high then U1A output will go low, and now U1B will go high to maintain high voltage level of U1A via R2, so we can release our finger without loosing the last state. Touching the pad again after we release our pr...

Description The Basic Alarm Circuit has an automatic Exit/Entry Zone - an Instant Alarm Zone that will accept both normally-closed and normally-open triggering devices - and an "Always On" 24-hour Personal Attack/Tamper Zone. By using the Expansion Modules - you can add as many extra alarm zones as you require. Schematic Diagram The Alarm is armed and disarmed by SW1. Before you move the switch to the "set" position - all the green LEDs should be lighting. You then have up to about a minute to leave the building. As you do so - the Buzzer will sound. It should stop sounding when you close the door behind you. This indicates that the Exit/Entry loop has been successfully restored within the time allowed.  When you re-enter the building - you have up to about a minute to move SW1 to the "off" position. If SW1 is not switched off in time - the relay will energize - and the main bell will ring. It will continue ringing for up to about 40 minutes. But it can...

This is a simple 741 Timer Circuit Diagram. In this circuit Rl and R2 hold the inverting input at half supply voltage. R4 applies feedback to increase the input impedance at pin 3. Pin 3, the nonin-verting input, is connected to the junction of R3 and C. After the switch is opened, C charges via R3. When the capacitor has charged sufficiently for the potential at pin 3 to exceed that at pin 2 the output abruptly changes from 0 V to positive line potential. If reverse polarity operation is required, simply transpose R3 and CR3 and C can be any values. Time delays from a fraction of a second to several hours can be obtained by judicious selection. The time delay—independent of supply voltage —is 0CR seconds where C is in farads.   Build a 741 Timer Circuit Diagram

 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 ...

This circuit has been very useful in filling a header tank for a reticulated water supply on a farm. Eight troughs are supplied in different paddocks where a lack of water would have serious consequences for the stock. In the past, the tank had been filled daily by a time clock which was not successful. During hot weather, the stock would empty the tank on a regular basis and then be without water for several hours or the tank would overflow and flood the area if the weather was wet and the cattle did not drink much.1 Automatic Water Tank Filler Circuit Diagram Automatic Water Tank Filler Schematic Circuit Diagram The circuit described has been used to maintain the level of water in the header tank within prescribed limits. It controls a 3HP submersible bore pump which has a high starting current, necessitating a solid-state relay sufficient to take the starting load. Two Darlington transistors, Q1 & Q3, in conjunction with Q2 & Q4, are connected to the upper and lower water se...

This Simple Emergency Light and Alarm Circuit Diagram is permanently plugged into a mains socket andNI-CD batteries are trickle-charged. When a power outage occurs,the lamp automatically illuminates. Instead of illuminating alamp, an alarm sounder can be chosen.When power supply is restored, the lamp or the alarm isswitched-off. A switch provides a “latch-up” function, in orderto extend lamp or alarm operation even when power is restored.Circuit operation:Mains voltage is reduced to about 12V DC at C2`s terminals, bymeans of the reactance of C1 and the diode bridge (D1-D4). Thusavoids the use of a mains transformer.   Simple Emergency Light and Alarm Circuit Diagram Trickle-charging current for the battery B1 is provided by theseries resistor R3, D5 and the green LED D6 that also monitorsthe presence of mains supply and correct battery charging.Q2 & Q3 form a self-latching pair that start operatingwhen a power outage occurs. In this case, Q1 biasing becomespositive, so this tr...

This simple key-operated gate locking system allows only those persons who know the preset code to open the gate. The code is to be entered from the keypad within the preset time to operate the motor fitted in the gate. If anyone trying to open the gate presses a wrong key in the keypad, the system is disabled and, at the same time, sounds an alarm to alert you of an unauthorized entry. Figs 1 and 2 show the block and circuit diagrams of the key-operated code locking system, respectively. Connect points A, B, C, D, E, F and ground of the circuit to the respective points of the keypad. Keys S7, S16, S14 and S3 are used here for code entry, and the remaining keys are used for disabling the system. It is very important to press the keys in that order to form the code. To start the motor of the gate, press switches S7, S16, S14 and S3 sequentially. If the keys are pressed in a different order from the preset order, the system will lock automatically and the motor will not start. Fig. 1: Bl...

The car cigarette lighter socket does not only light cigarettes, but can be utilized as an electrical channel for powering tools to work on the car such as laptops and other electronic devices. The following circuit diagram shows a way of powering a two-way mobile radio using the LM317 T voltage regulator . The LM317 T is an adjustable 3-terminal positive voltage regulator that efficiently provides a load current of 1.5 Amps over an output range of 1.2 V and 37 V. With reference to the circuit, it can accept 14 volts without any hassle and the voltage can be controlled easily with the use of a potentiometer, a 3-terminal resister with sliding contact. The whole circuit will contain the following components:  Printed Circuit Board (PCB) Resistor 1 (R1): 270 ohms Resistor 2 (R2): 2K carbon potentiometer Capacitor 1 (C1): 100nF Capacitor 2 (C2): 1uF tantalum LM317T Voltage Regulator Heat Sink DC Power Jacks Green LED: Power Red LED: Over Voltage Zener Diode: over voltage LED switch Th...

Two Light Emitting Diodes slowly light up and fade away due to the circuitry, giving it a feel of blinking red eyes in darkness. It is the perfect way to set up your own horror show in Halloween. It can also be installed in series for the Christmas tree or during Diwali or a decorative power indicator for the daily appliance. A 3 volt linear wave is generated at Pin 1 via LM 1458 IC and followed by a transistor which buffers the emission. A 47 K resistance coupled with a 22uF capacitor is joined at Pin2 to limit the frequency to 0.5Hz. The rate can be varied using a 100K pot(potentiometer) replacing the 47K resistor. Two operational amplifiers govern the circuit. The transitional voltage is produced by the first op-amp which slowly modulates voltage between 3 to 6 volts. The second op-amp supplies alternating voltage of 2 and 7 volts to charge the capacitor and discharge it via constant current. Two 47K resistors establish a fixed voltage when joined across Pin 3 & 6 to keep...

This is an efficient flyback driver for modern cylindrical rectified television flybacks. Many sites doesn't provide circuits driving these transformers, they simply say that they are bad. I don't agree. In fact I built this circuit. I spent a lot of time for finding resonant frequency (around 15Khz) and duty cycle. These transformers best work at around 90% duty cycle. You may notice corona breakdown at terminals and pfffff sound (as well as the ozone smell) when adjusting the off time trimmer to near 500-300 ohms. Of course it will work for other tipes of flyback as frequency and duty cycle have a large range.  Flyback Transformer Driver Circuit Diagram Frequency range can be increased using multiposition switch for other values of C3 capacitor ,for example 2 nF for 80KHz-200000KHz, but didn't found flybacks with so high resonant frequencies, in addition with higher values of c3 , eg 200nF, 2uF the frequency will drop making possible the use of ignition coils, and rectifi...

This is an Infrared beam breaking alarm ideal to use in entry or passages.It is based on the working of the popular IR sensor Module TSOP 1738 which senses 38 kHz Infrared pulses from the IR LED of the transmitter. Range of the circuit is about 5 meters if the transmitter and receiver are properly aligned TSOP 1738 IR sensor module responds to only 38kHz pulsed infrared rays. It will not sense continuous IR ray from the IR LED.So a transmitter circuit(as one in TV remote handset) based on 555 IC is required. Any standard transmitter circuit based on 555 IC can be used. But its output should be 38kHz exactly. TSOP 1738 gives 5 volt output and 5mA current in the off position.  That is when IR rays are not available.Its output is current sinking so that when it receives 38kHz IR rays, output becomes zero.Pin 2 of the module should get a supply voltage between 4.5 to 6 volts.Higher voltage above 6 volts will destroy the device. The module is generally immune to ambient light, but may r...

This Auto Anti-Hijack Alarm Circuit Diagram was designed primarily for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the Siren will sound. Where it differs from the first two alarms - is in what happens next. I'm obliged to Victor Montanez from the USA who suggested that the engine cut-out should not operate - until the vehicle comes to a stop. That way - the engine will not fail suddenly or unexpectedly. And the hijacker will retain control. I haven't been able to implement Victor's excellent suggestion completely - because I couldn't think of a simple, reliable and universally applicable way of sensing when the vehicle has come to a stop. Instead - I have postponed engine failure until the ignition is switched off. Once the thief turns off the ignition - the engine will not re-start. Clearly - there is ...

Using LT3582 -12 dual channel DC DC converter integrated circuit, manufactured by Linear Technology, can be designed a very simple step up dc converter. This 5 to 12V c converter electronic project provide both positive and negative outputs required in many biasing applications such as active matrix OLED (organic light-emitting diode)displays as well as CCD (charge coupled device) applications. The LT3582 offer an I2C interface that can dynamically program output voltages, power sequencing and output voltage ramps as the application requires. The LT3582’s positive output voltage can be set between 3.2V and 12.775 in 25mV steps, whereas the negative output can be set between -1.2V and -13.95V in 50mV steps. The LT3582-12 is preconfigured with ±12V output, requiring no future programming.

Warning! The circuit is connected to 220Vac mains, then some parts in the circuit board are subjected to lethal potential!. Avoid touching the circuit when plugged and enclose it in a plastic box. Powered by two AA NI-CD batteries Four switchable options Circuit diagram       Parts: R1 220K 1/4W Resistor R2 470R 1/2W Resistor R3 390R 1/4W Resistor R4 1K5 1/4W Resistor R5 1R 1/4W Resistor R6 10K 1/4W Resistor R7 330K 1/4W Resistor R8 470R 1/4W Resistor R9 100R 1/4W Resistor C1 330nF 400V Polyester Capacitor C2 10µF 63V Electrolytic Capacitor C3 100nF 63V Polyester Capacitor C4 10nF 63V Polyester Capacitor D1-D5 1N4007 1000V 1A Diodes D6 LED Green (any shape) D7 1N4148 75V 150mA Diode Q1,Q3,Q4 BC547 45V 100mA NPN Transistors Q2,Q5 BC327 45V 800mA PNP Transistors SW1,SW2 SPST Switches SW3 SPDT Switch LP1 2.2V or 2.5V 250-300mA Torch Lamp SPKR 8 Ohm Loudspeaker B1 2.5V Battery (two AA NI-CD rechargeable cells wired in series) PL1 Male Mains plug Device purpose: This circuit...

Small 1.5V to 5V or 12V DC/DC converter with LT1073 chip. The IC is available in three different versions, depending on output voltage. Two with fixed output voltage of 5V and 12V, and the most interesting that can be adjusted. The adjustment is done through a voltage divider with two resistors, of mass, output and Terminal 8, internally connected to the voltage comparator IC, which is responsible for stabilizing the output voltage. LT1073 has an internal everything you need to make a small DC / DC converter with a low operating voltage of only 95μA 1V and consumption without load. If you do not have a meter inductance, the inductive part of the drive is a bit more complicated to make, but we shall see some possible solutions. Capacitor also recommended by the manufacturer for the circuit is a bit hard to get, I have used a tantalum recovered from another power source, and the ripple voltage at the output is quite low. Last but not least, say that the diode has to be a fast, not...