TREE

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...

Automatic Voltage Stabilizer with PIC16F873A Download links for the article:  Google docs (go to the link, click File in the PDF window, then click Download): https://docs.google.com/file/d/0B4SoPFPRNziHb3VrX3JhWko3d1E/edit Scribd link: http://www.scribd.com/doc/207498741/Automatic-Voltage-Stabilizer-with-PIC16F873A 4shared download link: http://www.4shared.com/office/ktU0k9dqba/Voltage_Stabilizer.html You can download all the files related to the voltage stabilizer: Google docs (go to the link, click File in the PDF window, then click Download): Code: https://drive.google.com/file/d/0B4SoPFPRNziHbWtkVUc1VUM1REU/edit?usp=sharing HEX: https://drive.google.com/file/d/0B4SoPFPRNziHSVJ1a0t2STNDd3M/edit?usp=sharing PCB: https://drive.google.com/file/d/0B4SoPFPRNziHdkE0SzI4SDQ5V3M/edit?usp=sharing PCB images: https://drive.google.com/file/d/0B4SoPFPRNziHNEtSQlVtX2x4VWc/edit?usp=sharing https://drive.google.com/file/d/0B4SoPFPRNziHQXl2eWtydmh3WkU/edit?usp=sharing https://drive.google.c...

This is the simple circuit of automatic emergency light. It is called dark dependent circuit. A 555 timer IC and LDR is used for this configuration. When light fall on the LDR, its resistance is decrease and in dark position its resistance is going high. Using these characteristics of LDR, automatic emergency light is made. Circuit Diagram : Simple Automatic Emergency Light Circuit Diagram LDR is called Light Dependent Resistor. Its resistance is inversely proportional to the falling light on its surface. In dark, its resistance is approximately 7k to 10k. When light fall on its surface, its resistance is decrease to less than 1k. In the circuit, a voltage divider arrangement circuit is used here with LDR and 10K variable resistor. When light fall on the surface of LDR, the resistance decrease to 1k. So the voltage of the timer pin-6 is greater than 2/3 of +Vcc. For this reason the output pin-3 goes low. The base voltage of transistor BC547 is less than 0.75 volt. The transistor ...

How to make a Simple Automatic Street Lights Intensity Control. White LED (Light Emitting Diodes) substitutes HID lanterns in road illumination system to add on dim element. 8051 family’s micro-controller is bring into play to control the power by growing pulse width transformed pointers that impels a MOSFET to swap the Light Emitting Diodes accordingly to accomplish most wanted function. Automatic Street Lights Intensity Control Circuit Diagram In the current system, maximum lightning over the freeways is completed through HID (High Intensity Discharge lamps), the energy utilization of HID lamps/lanterns are high. The intensity of HID lamps cannot be controlled, in harmony to the necessity, therefore there is a requirement to swap to a substitute way of illumination system i.e., by making use of LEDs. This lighting system is constructed to conquer the disadvantages of High Intensity Discharge lamps. This lightning system exhibits the utilization of the Light emitting diodes or LED’s a...

Description In many cases, the dimmer presented here may be built into a wall-mounted box containing the light switch. It is intended for use with 240 V incandescent lamps only. When it is fitted, and the light is switched on, the lamp does not come on fully for about 400 ms (which is not noticeable). When the light is switched off, it stays on unchanged for about 20 s, and then goes out gradually. This has the advantage that it is not immediately dark when the light is switched off. When light switch S1 is turned on, capacitor C2 is charged via R1, C1 and bridge rectifier D1–D4. Zener diode D5 limits the potential across C2 to about 15 V. After a short while, diode D6 lights, whereupon a potential difference ensues across light sensitive resistor R3, which is sufficient to trigger triac Tr1. Circuit diagram:   The light then comes on. When the light switch is turned off, C2 is discharged via P1, R2 and D6. When the potential across C2 drops, the brightness of the LED diminishes, s...

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...

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...

There have been lot of problems in street lights. Major problem in some places is every evening a person has to come and switch ON the street light and it should be again switched off in morning. Yes, this may not be the situation in everywhere but exists in many places. So this problem can be overcome by using a simple circuit. Below shown circuit will be automatically switched ON and OFF during night and morning times respectively. Circuit diagram : Simple Automatic street light Circuit Diagram In above circuit R1 can be used to adjust the sensitivity. And the working of the circuit is very simple. The LDR will have very low resistance during day time so the transistor Q1 will be in OFF condition. And during night time the resistance will be very high so automatically the transistor Q1 will be ON. The Q1 is PNP transistor and the emitter of Q1 is given to base of Q2. So the Q2 transistor will be ON only if the transistor Q1 is ON. The TRIAC is used in the circuit to make is circ...

Per request the circuit today we have relay circuit. It is worth noting again that the diagram provides a time delay of about 0.5 seconds for every microfarad in the value of capacitor C1. This permits delays of up to several minutes. If desired, the delay periods can be made variable by replacing resistor R2 with a fixed and variable resistor in series whose nominal values are approximately equal of the total value of R2 (680K). Automatic Turn Off Relay Circuit Diagram

Driving the highway with your high-beam headlights can really increase your visibility, but can be a blinding hazard for other drivers. This simple circuit can be wired into your headlight switch to provide automatic switching between high and low beam headlights when there is oncoming traffic. It does this by sensing the lights of that traffic. In this way, you can drive safely with your high-beams on without blinding other drivers. Automatic Headlight Brightness Switch Circuit Diagram Parts Part    Total Qty    Description R1              1         5K 1/4W Resistor   R2,R3,R4   3         5K Pot   Q1              1         NPN Phototransistor   Q2              1    ...

This simple emergency lamp circuit uses very components and yet is able to provide some useful service. The shown device is able to switch ON automatically when mains power fails, illuminating all the connected LEDs.As soon as power is restored, the LEDs shut off automatically and the connected starts charging through the built in power supply. The circuit employs a transformerless power supply for initiating the explained automatic actions and also for trickle charging the connected battery. Parts List R1 = 220K, R2 = 10K, D1, D2, D3 = 1N4007, Z1 = 15V 1watt, zener diode, C1 = 105/400V C2 = 100uF/25V T1 = 2N2907, or 8550, or BD 140 Z1 = 12V, 1 watt LEDs = white, high bright type.

Electrical appliances accidentally left on  in (holiday) homes left unoccupied for a  short or a long period consume power  unnecessarily and can present a fire hazard. Everyone will be familiar with those  nagging thoughts, a few miles down the  road from the house: “Did I remember  to switch off the coffee machine? The  lights? The oven?”  Automatic AC Power Switch Circuit Diagram Hotel rooms are often equipped with a  switch near the main door which enables the power supply to everything in  the room only when the plastic card (which  might contain a chip or have a magnetic strip  or a pattern of holes) that serves as the room  key is inserted. The circuit idea given here  to switch off lights and other appliances is  along the same lines. The solution is surprisingly simple.  A reed contact is fitted to the frame of the main entrance door, and a matching magnet  is attached to the door itself such t...

This circuit will automatically switch on several mains-powered "slave" loads when a "master" load is turned on. For example, it will switch on the amplifier and CD player in a stereo system when the receiver is turned on. It works by sensing the current draw of the "master" device through a low value high wattage resistor using a comparator. The output of that comparator then switches on the "slave" relay. The circuit can be built into a power bar, extension cord or power center to provide a convenient set of "smart" outlets that switch on when the master appliance is powered (turn on the computer monitor and the computer, printer and other peripherals come on as well). Automatic Load Sensing Power Switch Circuit Diagram Parts List: Notes: This circuit is designed for 120V operation. For 240V operation, resistors R2 and R6 will need to be changed. A maximum of 5A can be used as the master unless the wattage of R1 is increased S1 provid...