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D) Failure to pick up & seal 1) Low voltage Remedy: Correct voltage conditions-In case of persistent low voltage change to lower voltage coil or change transformer tap 2) Coil open or shorted Remedy: Replace the coil 3) Mechanical obstruction Remedy: Clean and check free movement of contact assembly 4) Coil excitation without arc chute or arc chute not properly fixed Remedy: Ensure proper fitting of arc chute .....

A photo diode is a PN junction or PIN structure that when light reaches the junction, it excites an electron thereby creating a free electron positively charged. This mechanism is also known as the photoelectric effect, common in transistors, diodes and ICs are made ​​of semiconductors, and contain PN junctions. Almost all of the potentially active constituents are a photo diode and may be used as a photo sensor. The PN junction needs to be exposed to light, so to use a semiconductor diode as a light bulb must have a transparent glass, these diodes with  these characteristics can be used to measure the light intensity.  Circuit diagram of a light intensity meter with diode.   a test circuit diode light sensor List of components: D1 1n148 or any other photo-sensitive element T1, T2 BC548 or similar C1 680n R1 2M Above this circuit that is very popular, it works with LEDs, photodiodes and photo-resistors. V is a voltmeter which can be a multimeter.

It is sometimes disturbing to have a AM radio in a countryside and not being able to get the reception clearly. It is simply because of the distance of the radio station and also the strength of the station. The only solution is to attach a powerful antenna to the receiving radio the uniqueness of the antenna lies in its simplicity and cost. The basic knowledge of making an antenna is there in the back end. Generally, the frequency range of amplitude modulation in 560 to 1650 KHz in order to resonate the LC circuit that that is the antenna (2πfL=1/(2πf_c )) 4πf^2 LC=1.Using this formula and using a 30- 450 pF gang condenser the handy inductance built on a 350ft long PVC pipe works quite well. The inductance built around a PVC pipe is basically an air core inductor, the inductance of which is govern by the formula L=(R^2 N^2)/(9R+10l) where L is inductance in μH, R is coil radius in inches, l is coil length in inches and N is number of turns. The calculated inductance in tune with 3...

I have built this amplifier and it does sound good. It requires a preamp as it hasn't got much gain. It requires big heat sinks and a large transformer and a great power supply and careful wiring, but in the end it is xtremely simple and it sounds very good. The zener diode rejects any ripple coming from the power supply, But you still only want a ripple of 10mV max. The ripple reaching the input is amplified, so the zener diode gets rid of that, but whatever ripple there is will still reach the power stage.

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....

DC13.8V to DC250V Inverter Circuit Diagram I have done a lot of work with valves in recent years. For me valves have many advantages, least of all the price; since they are now "obsolete" it is quite easy to get hold of them for next to nothing at rally's and junk sales. I recently purchased a couple of hundred battery valves for less than SEK1 (US$ 0.15) each. The biggest problem with valves is the PSU needed to provide +250 vDC and 6.3 vAC for the filaments. The transformers are no-longer available at a reasonable price, but a pair of 12v-6v-0v-6v-12v mains transformers will do the job just as well. For portable use only one transformer is required together with a pair of power transistors such as 2N3055 etc.

500W 12V to 220V Inverter Circuit Diagram   This is a 500W DC-to-AC inverter circuit diagram which produces an AC output at line frequency and voltage. 12VDC to 220V 50Hz inverter circuit will power 220V or 110V appliances from 12V car battery. The circuit is easy to make and is low cost. Use proper transformer. The output (in watts) is up to you by selecting different power rating transformer and power transistor rating. If you load electronic device which require 120V AC, then use transformer with 120V in output.

Apple will unveil the next edition of the iPhone at a major press event on Sept. 10, according to All Things D.Other than the purported date for the unveiling of the so-called iPhone 6, the site's Ina Fried did not offer any details about what else we might expect from Apple with the arrival of the company's first new smartphone since the debut of the iPhone 5 last September. If Apple does lift the curtain on its next-generation iPhone on Sept. 10, it would be two days short of a full year since the iPhone 5 was revealed. While Apple CEO Tim Cook is rumored to be under pressure from Apple's board to step up the pace of innovation and product release schedules, that lag between new iPhone releases wouldn't be particularly unusual for the company—Apple went 16 months between introducing the iPhone 4 and iPhone 4S , for example. But as Fried noted, even as Apple has continued to enjoy robust sales of the iPhone this year, the company has seen its overall share of the gl...

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...

Build a simple 500W Cheap 12V to 220V inverter Circuit Diagram.  In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer. 500W Cheap 12V to 220V inverter Circuit Diagram How to calculate transformer rating The basic formula is P=VI and between input output of the transformer we have Power input = Power output For example if we want a 220W output at 220V then we need 1A at the output. Then at the input we must have at least 18.3V at 12V because: 12V*18.3 = 220v*1 So you have to wind the step up transformer 12v to 220v but input winding must be capable to bear 20A.   Source: www.circuitsproject.com

Regulated Power Supply This project is a normal DC regulated power supply that is a variable DC voltage range from 5V to 15V. It can supply current up to  400mA to power the various circuits for your electronic projects. The voltage output is varied by using the potentiometer V.R1. In this circuit, the input line power supply is designed for 240V.A.C. If 110VAC input is used, alter the ratings of the varistor to 150VAC & the transformer ratio to 110V/12V.  Fuse F1 is used as a protection in case there's any short circuit in the circuit. Varistor V1 is connected in parallel to the input of the line voltage to clamp the surge voltage from the line to a reasonable level that helps to protect the transformer & other circuitry. One time the voltage level surge to a high level beyond the ability of the varistor to absorb it, fuse F1 or varistor V1 or both will burn. If this circuit failed after a period of operation, check that the fuse & the varistor are still in nice c...

This is a Simple1.5.4.5V to 9V Converter Circuit Diagram. Build a Simple1.5.4.5V to 9V Converter Circuit Diagram. 1.5.4.5V to 9V Converter Circuit Diagram

The power inverter can be useful anywhere where you do not have to hand power outlet, like in your car, trailer or cottage. It is powered by mains appliances such as radios, tape recorders, televisions, electric shavers, lamps, Compact fluorescent or charger for mobile phone etc. The maximum load depends on the inverter transformer used as transistors can be up to 150W. Inverter 12VDC to 230V 50Hz Circuit Diagram The source frequency of 50 Hz is known 555 timer, frequency, impact resistance Rx and capacitor Cx. The switching function is performed by two MOS transistors with channel N. The state resistance is only 0.2 R. One is driven directly from the IO, the other through an inverter with BC547. Gate transistors have a relatively large capacity of about 1 nF, must be driven by the least possible resistance. The output resistance of IC 555 is just about the 100R, which is good. BC547 collector resistance must be as small as possible (you can use less of its current is negligible agains...

  A very efficient 6V to 15V DC to DC converter using LM2585 is shown here. LM2585 is a monolithic integrated voltage converter IC that can be used in various applications like flyback converters, boost converters, forward converters, multiple output converters etc. The circuit requires minimum number of external components and the IC can source up to 3A output current. Circuit diagram : 6 to 15V DC to DC Converter Circuit Diagram Here the IC is wired as a boost converter where resistors R1 and R2 are used to set the output voltage .The junction of R1 and R2 is connected to the feedback pin of IC1. Capacitor C4 is the input filter while capacitor C1 the filter for output. Network comprising of resistor R1 and capacitor C2 is meant for frequency compensation. Inductor L1 stores the energy for acquiring boost conversion. Notes:      Assemble the circuit on a good quality PCB. LM2585 requires a heatsink. Output voltage is according to the equation Vout =( (R1/R2)+1) x 1.23. C...

This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also modify it for different voltages. Notes L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidal core with a 40mm outside diameter. Different values of D3 can be used to get different output voltages from about 0.6V to around 30V. Note that at higher voltages the circuit might not perform as well and may not produce as much current. You may also need to use a larger C3 for higher voltages and/or higher currents. You can use a larger value for C3 to provide better filtering. The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V. 6V to 12V Converter Circuit Diagram   Parts R1, R4 2 2.2K 1/4W Resistor R2, R3 2 4.7K 1/4W Resistor R5 1 1K 1/4W Resistor R6 1 1.5...

This is a 5V to 12V DC-DC step-up (boost) converter circuitry that is especially ideal for the USB powered applications. First of all a USB port has two current supply modes. Before detecting the connected device, it supplies maximum 100mA to the load. After recognizing the device, it increases the output current up to 500mA. In this circuit, controller (LT1618) also provides two input current modes. 100mA and 500mA input modes can be selected by the user. USB 5V to 12V DC-DC Step-Up Converter by LT1618  Output currents are limited due to the increased potential difference at the output. When the demand of the load increases, output voltage will start to decrease. For example, if the circuit operates in the 100 mA input mode, when the load is 35 mA, the output voltage will be kept at 12V. But if the load increases to 50 mA, output voltage will reduce to 8V to maintain the constant 100 mA input current.

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...

This is a Simple1.5.4.5V to 9V Converter Circuit Diagram. Build a Simple1.5.4.5V to 9V Converter Circuit Diagram. 1.5.4.5V to 9V Converter Circuit Diagram

 12V to 220V 100W Transistor Inverter Circuit Diagram 12V to 220V 100W transistor based power inverter.