HARTLEY OSCILLATOR

HARTLEY OSCILLATOR

The Hartley Oscillator is characterised by an LC circuit in its collector. The base of the transistor is held steady and a small amount of signal is taken from a tapping on the inductor and fed to the emitter to keep the transistor in oscillation.


The transformer can be any speaker transformer with centre-tapped primary.

The frequency is adjusted by changing the 470p.
 

HARTLEY OSCILLATOR

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COLPITTS OSCILLATOR

COLPITTS OSCILLATOR


The Colpitts Oscillator is characterised by tapping the mid-point of the capacitive side of the oscillator section.
The inductor can be the primary side of a speaker transformer. The feedback comes via the inductor.
 
 

COLPITTS OSCILLATOR

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TOUCH SWITCH

TOUCH SWITCH

This circuit detects the skin resistance of a finger to deliver a very small current to the super-alpha pair of transistors to turn the circuit ON. The output of the "super transistor" turns on the BC 557 transistor. The voltage on the top of the globe is passed to the front of the circuit via the 4M7 to take the place of your finger and the circuit remains ON.

To turn the circuit OFF, a finger on the OFF pads will activate the first transistor and this will rob the "super transistor" of voltage and the circuit will turn OFF.

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SIGNAL INJECTOR

SIGNAL INJECTOR

This circuit is rich in harmonics and is ideal for testing amplifier circuits. To find a fault in an amplifier, connect the earth clip to the 0v rail and move through each stage, starting at the speaker. An increase in volume should be heard at each preceding stage. This Injects will also go through the IF stages of radios and FM sound sections in TV's.

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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LIE DETECTOR

LIE DETECTOR

This circuit detects the resistance between your fingers to produce an oscillation. The detection-points will detect resistances as high as 300k and as the resistance decreases, the frequency increases.

Separate the two touch pads and attach them to the back of each hand. As the subject feels nervous, he will sweat and change the frequency of the circuit.

The photos show the circuit built on PC boards with separate touch pads.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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TICKING BOMB

TICKING BOMB

This circuit produces a sound similar to a loud clicking clock. The frequency of the tick is adjusted by the 220k pot.


The circuit starts by charging the 2u2 and when 0.65v is on the base of the NPN transistor, it starts to turn on. This turns on the BC 557 and the voltage on the collector rises. This pushes the small charge on the 2u2 into the base of the BC547 to turn it on more.

This continues when the negative end of the 2u2 is above 0.65v and now the electro starts to charge in the opposite direction until both transistors are fully turned on. The BC 547 receives less current into the base and it starts to turn off. Both transistors turn off very quickly and the cycle starts again.
 
source :  http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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SIREN

SIREN

This circuit produces a wailing or siren sound that gradually increases and decreases in frequency as the 100u charges and discharges when the push-button is pressed and released. In other words, the circuit is not automatic. You need to press the button and release it to produce the up/down sound.

source :

http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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ON - OFF VIA MOMENTARY PUSH-BUTTONS

ON - OFF VIA MOMENTARY PUSH-BUTTONS


This circuit will supply current to the load RL. The maximum current will depend on the second transistor. The circuit is turned on via the "ON" push button and this action puts a current through the load and thus a voltage develops across the load. This voltage is passed to the PNP transistor and it turns ON. The collector of the PNP keeps the power transistor ON.

To turn the circuit OFF, the "OFF" button is pressed momentarily. The 1k between base and emitter of the power transistor prevents the base floating or receiving any slight current from the PNP transistor that would keep the circuit latched ON.

The circuit was originally designed by a Professor of Engineering at Penn State University. It had 4 mistakes. So much for testing a circuit!!!! It has been corrected in the circuit on the left.
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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CONSTANT CURRENT SOURCE

CONSTANT CURRENT SOURCE

This circuit provides a constant current to the LED. The LED can be replaced by any other component and the current through it will depend on the value of R2. Suppose R2 is 560R. When 1mA flows through R2, 0.56v will develop across this resistor and begin to turn on the BC547. This will rob the base of BD 679 with turn-on voltage and the transistor turns off slightly. If the supply voltage increases, this will try to increase the current through the circuit. If the current tries to increase, the voltage across R2 increases and the BD 679 turns off more and the additional voltage appears across the BD 679.

If R2 is 56R, the current through the circuit will be 10mA. If R2 is 5R6, the current through the circuit will be 100mA - although you cannot pass 100mA through a LED without damaging it.

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12v RELAY ON 6V SUPPLY

12v RELAY ON 6V SUPPLY

This circuit allows a 12v relay to operate on a 6v or 9v supply. Most 12v relays need about 12v to "pull-in" but will "hold" on about 6v. The 220u charges via the 2k2 and bottom diode. When an input above 1.5v is applied to the input of the circuit, both transistors are turned ON and the 5v across the electrolytic causes the negative end of the electro to go below the 0v rail by about 4.5v and this puts about 10v across the relay.

Alternatively you can rewind a 12v relay by removing about half the turns.

Join up what is left to the terminals. Replace the turns you took off, by connecting them in parallel with the original half, making sure the turns go the same way around
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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LED DETECTS LIGHT

LED DETECTS LIGHT

All LEDs give off light of a particular colour but some LEDs are also able to detect light. Obviously they are not as good as a device that has been specially made to detect light; such as solar cell, photocell, photo resistor, light dependent resistor, photo transistor, photo diode and other photo sensitive devices.


A green LED will detect light and a high-bright red LED will respond about 100 times better than a green LED, but the LED in this position in the circuit is classified as very high impedance and it requires a considerable amount of amplification to turn the detection into a worthwhile current-source.

All other LEDs respond very poorly and are not worth trying.

The accompanying circuit amplifies the output of the LED and enables it to be used for a number of applications.

The LED only responds when the light enters the end of the LED and this makes it ideal for solar trackers and any time there is a large difference between the dark and light conditions. It will not detect the light in a room unless the lamp is very close.
 

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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WHITE LINE FOLLOWER

WHITE LINE FOLLOWER

This circuit can be used for a toy car to follow a white line. The motor is either a 3v type with gearing to steer the car or a rotary actuator or a servo motor.


When equal light is detected by the photo resistors the voltage on the base of the first transistor will be mid rail and the circuit is adjusted via the 2k2 pot so the motor does not receive any voltage. When one of the LDR's receives more (or less) light, the motor is activated. And the same thing happens when the other LDR receives less or more light.
 

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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DANCING FLOWER

DANCING FLOWER

This circuit was taken from a dancing flower.


A motor at the base of the flower had a shaft up the stem and when the microphone detected music, the bent shaft made the flower wiggle and move.

The circuit will respond to a whistle, music or noise.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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1.5v LED FLASHER

1.5v LED FLASHER

This will flash a LED, using a single 1.5v cell. It will even flash a white LED even though this type of LED needs about 3.2v to 3.6v for operation.


The circuit takes about 2mA but produces a very bright flash.

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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LED FLASHER WITH ONE TRANSISTOR

LED FLASHER WITH ONE TRANSISTOR

This is a novel flasher circuit using a single driver transistor that takes its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED will not work.

The flash rate cannot be altered by the brightness of the high-bright white LED can be adjusted by altering the 1k resistor across the 100u electrolytic to 4k7 or 10k.

The 1k resistor discharges the 100u so that when the transistor turns on, the charging current into the 100u illuminates the white LED.

If a 10k discharge resistor is used, the 100u is not fully discharged and the LED does not flash as bright.

All the parts in the photo are in the same places as in the circuit diagram to make it easy to see how the parts are connected.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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6 MILLION GAIN

6 MILLION GAIN

This circuit is so sensitive it will detect "mains hum." Simply move it across any wall and it will detect where the mains cable is located. It has a gain of about 200 x 200 x 200 = 6,000,000 and will also detect static electricity and the presence of your hand without any direct contact. You will be amazed what it detects! There is static electricity EVERYWHERE! The input of this circuit is classified as very high impedance.

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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SECOND SIMPLEST CIRCUIT

SECOND SIMPLEST CIRCUIT

This the second simplest circuit in the world. A second transistor has been added in place of your fingers. This transistor has a gain of about 200 and when you touch the points shown on the diagram, the LED will illuminate with the slightest touch. The transistor has amplified the current (through your fingers) about 200 times

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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WORLDS SIMPLEST CIRCUIT

WORLDS SIMPLEST CIRCUIT

This is the simplest circuit you can get. Any NPN transistor can be used.

Connect the LED, 220 ohm resistor and transistor as shown in the photo.

Touch the top point with two fingers of one hand and the lower point with

fingers of the other hand and squeeze.

The LED will turn on brighter when you squeeze harder.



Your body has resistance and when a voltage is present, current will flow though your body (fingers). The transistor is amplifying the current through your fingers about 200 times and this is enough to illuminate the LED.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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TRANSISTOR TESTER - 2

TRANSISTOR TESTER - 2

Here is another transistor tester.

This is basically a high gain amplifier with feedback that causes the LED to flash at a rate determined by the 10u and 330k resistor.

Remove one of the transistors and insert the unknown transistor. When it is NPN with the pins as shown in the photo, the LED will flash. To turn the unit off, remove one of the transistors.

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TRANSISTOR TESTER - 1

TRANSISTOR TESTER - 1

Transistor Tester - 1 project will test all types of transistors including Darlington and power. The circuit is set to test NPN types. To test PNP types, connect the 9v battery around the other way at points A and B.

10mH choke with 150 turns for the secondary


The transformer in the photo is a 10mH choke with 150 turns of 0.01mm wire wound over the 10mH winding. The two original pins (with the red and black leads) go to the primary winding and the fine wires are called the Sec.

Connect the transformer either way in the circuit and if it does not work, reverse either the primary or secondary (but not both).

Almost any transformer will work and any speaker will be suitable.

If you use the speaker transformer described in the Home Made Speaker Transformer article, use one-side of the primary.
 
 
TRANSISTOR TESTER-1


CIRCUIT

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SUPER EAR

SUPER EAR

This circuit is a very sensitive 3-transistor amplifier using a speaker transformer. This can be wound on a short length of ferrite rod as show above or 150 turns on a 10mH choke. The biasing of the middle transistor is set for 3v supply. The second and third transistors are not turned on during idle conditions and the quiescent current is just 5mA.

The project is ideal for listening to conversations or TV etc in another room with long leads connecting the microphone to the amplifier.

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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home made speaker transformer

home made speaker transformer

The speaker transformer is made by winding 50 turns of 0.25mm wire on a small length of 10mm dia ferrite rod.

The size and length of the rod does not matter - it is just the number of turns that makes the transformer work. This is called the secondary winding.

The primary winding is made by winding 300 turns of 0.01mm wire (this is very fine wire) over the secondary and ending with a loop of wire we call the centre tap.

Wind another 300 turns and this completes the transformer.

It does not matter which end of the secondary is connected to the top of the speaker.

It does not matter which end of the primary is connected to the collector of the transistor in the circuits in this book.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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5v REGULATED SUPPLY FROM 3V

5v REGULATED SUPPLY FROM 3V

This circuit will produce a 5v regulated output from 2 cells (3v). The output current is limited to 50mA but will be ideal for many microcontroller circuits.

The output voltage is set to 5v by the 3k9 and 560R resistors, making up a voltage divider network.
 

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1.5v to 9v INVERTER

1.5v to 9v INVERTER

This very clever circuit will convert 1.5v to 9v to take the place of those expensive 9v batteries.


But the clever part is the voltage regulating section. It reduces the current to less than 10mA when no current is being drawn from the output. You can use two or three old cells for the supply and the circuit will totally use up all the energy from the cells. It's a great circuit for using up those old cells. With a 470R load, the output current is 20mA and the voltage drop is less than 10mV. It is best to use 3 old cells as this will deliver about 2.5v to 3v and the circuit will produce an efficiency of about 70%. Adjust the 15k resistor for 9v.

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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12v TRICKLE CHARGER

12v TRICKLE CHARGER

The 12v Trickle Charger circuit uses a TIP3055 power transistor to limit the current to the battery by turning off when the battery voltage reaches approx 14v or if the current rises above 2 amp. The signal to turn off this transistor comes from two other transistors - the BC557 and BC 547.


Firstly, the circuit turns on fully via the BD139 and TIP3055. The BC557 and BC 547 do not come into operation at the moment. The current through the 0.47R creates a voltage across it to charge the 22u and this puts a voltage between the base and emitter of the BC547. The transistors turn on slightly and remove some of the turn-on voltage to the BD139 and this turns off the TIP3055 slightly.

This is how the 2 amp max is created.

As the battery voltage rises, the voltage divider made up of the 1k8 and 39k creates a 0.65v between base and emitter of the BC557 and it starts to turn on at approx 14v. This turns on the BC 547 and it robs the BD136 of "turn-on" voltage and the TIP3055 is nearly fully turned off.

All battery chargers in Australia must be earthed. The negative of the output is taken to the earth pin.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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MAKING A ZENER DIODE

MAKING A ZENER DIODE

Sometimes a zener diode of the required voltage is not available. Here are a number of components that produce a characteristic voltage across them. Since they all have different voltages, they can be placed in series to produce the voltage you need. A reference voltage as low as 0.65v is available and you need at least 1 to 3mA through the device(s) to put them in a state of conduction (breakdown).

source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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BENCH POWER SUPPLY

BENCH POWER SUPPLY

This power supply can be built in less than an hour on a piece of copper-laminate. The board acts as a heat-sink and the other components can be mounted as shown in the photo, by cutting strips to suit their placement.

The components are connected with enamelled wire and the transistor is bolted to the board to keep it cool.

The Bench Power Supply was designed to use old "C," "D" and lantern batteries, that's why there are no diodes or electrolytics. Collect all your old batteries and cells and connect them together to get at least 12v -14v.

The output of this power supply is regulated by a 10v zener made up of the characteristic zener voltage of 8.2v between the base-emitter leads of a BC547 transistor (in reverse bias) and approx 1.7v across a red LED. The circuit will deliver 0v - 9v at 500mA (depending on the life left in the cells your are using). The 10k pot adjusts the output voltage and the LED indicates the circuit is ON. It's a very good circuit to get the last of the energy from old cells.
 
source : http://www.talkingelectronics.com.au/projects/200TrCcts/200TrCcts.html

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6V to 12V Converter Circuit with BD679 - BC547

6V to 12V Converter Circuit with BD679- BC547

This is a design circuit for converter circuit. This circuit is based on transistor as controller the circuit. There are two types of transistor that is BC547 and BD679. This circuit is a simple design of converter or inverter. This is the figure of the circuit.

This inverter circuit can to 800mA of 12V power supply with a 6V. For example could you 12V Car Accessories (UK turning into a 6V?) Car. The circuit is simple, more than 75% efficiency and very helpful. By changing a few components you, you also change for different voltages.

Electronic Part List

R1, R4 2 .2 K 1/4W Resistor

R2, R3 47K 1/4W Resistor

R5 1K 1/4W Resistor

R6 15K 1/4W Resistor

R7 33K 1/4W Resistor

R8 10K 1/4W Resistor

C1, C2 0.1uF Ceramic Disc Capacitor

C3 470uF 25V electrolytic capacitor

1N914 diode D1

D2 Diode 1N4004

D3 12V 400mW Zener Diode

Q1, Q2, Q4 BC547 NPN transistor

BD679 NPN transistor Q3

L1 See Notes

Notes

1. L1 is a custom inductor wound with about 80 turns 0.5 mm magnet wire a ring around the core with an outer diameter of 40 mm.



2. Different values of D3 can be used to obtain different output voltages from 0.6V to 30V is about. Note that at higher voltages, the circuit could perform just as well and can not produce much electricity. You may need to use a larger C3 for higher voltages and / or higher currents.



3. You can use a larger value for C3, in order to achieve a better filtering.



4. The circuit requires about 2A from the 6V supply to provide the full 800mA at 12V.

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5V power supply

5V power supply

Simple 5V power supply for digital circuits

Summary of circuit features

Brief description of operation: Gives out well regulated +5V output, output current capability of 100 mA

Circuit protection: Built-in overheating protection shuts down output when regulator IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic components

Design testing: Based on datasheet example circuit, I have used this circuit succesfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unreglated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input transformer cost

Circuit description



This circuit is a small +5V power supply, which is useful when experimenting with digital electronics. Small inexpensive wall tranformers with variable output voltage are available from any electronics shop and supermarket. Those transformers are easily available, but usually their voltage regulation is very poor, which makes then not very usable for digital circuit experimenter unless a better regulation can be achieved in some way. The following circuit is the answer to the problem.



This circuit can give +5V output at about 150 mA current, but it can be increased to 1 A when good cooling is added to 7805 regulator chip. The circuit has over overload and therminal protection.
  Circuit diagram of the power supply

The capacitors must have enough high voltage rating to safely handle the input voltage feed to circuit. The circuit is very easy to build for example into a piece of veroboard.

more info

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schematic diagram voltage regulator

9V to 2A PSU - A simple 9 Volt 2 amp supply using a single IC regulator. There is little to be said about this circuit. All work is done by regulator. The 78S09 can deliver up to 2 amps continuous output whilst maintaining a low noise and very well regulated supply.

1.3V Power Supply - This is a replacement power source for 1.3V mercury cells or or small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital rmometer.

1.5A High Efficiency Synchronous Switching Regulator Evaluation Board - evaluation board is designed to supply 3.3V at 15 mA up to 1.5A. input voltage range is 4V to 14V. Components were selected based on design procedure in LM2651 datasheet. PCB layout is critical to reduce noise and ensure.

13.8V 20A Power Supply - As is commonly the case, this supply was born of necessity. There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous. Simply use a bigger transformer, bridge rectifier and more capacitors and output transistors to get more current. The basic circuit should be good for up to 100A or so, using a 5A TO3 regulator IC, but it can obviously be increased further (if you really do need a 500A supply!).


78xx power supply - Of all the voltage regulator ICs, the 78xx family is by far the most established. Not surprisingly! It's difficult to get performance this good with so few outside components necessary. Just like the famous LM317, the 78xx family incorporates.

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2sd2599

2sd2599

TOSHIBA TRANSISTOR SILICON NPN TRIPLE DIFFUSED MESA TYPE

2SD2599

HORIZONTAL DEFLECTION OUTPUT FOR COLOR TV
datasheet transistor 2sd2599

l High Voltage

: VCBO = 1500 V

l Low Saturation Voltage : VCE (sat) = 8 V (Max.)

l High Speed

: tf = 0.5 µs (Typ.)

l Bult-in Damper Type

l Collector Metal (Fin) is Fully Covered with Mold Resin.

MAXIMUM RATINGS (Tc = 25°C)
download pdf datasheet 2sd2599

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Circuit Diagram for 250 W HID Metal Halide Electronic Ballast

Circuit Diagram for 250 W HID Metal Halide Electronic Ballast

The following file is an application note from st.com describing the two stages of electronic ballast for a 250 W HID (high-intensity discharge) metal halide lamp. The ballast is composed of a boost converter (power factor controller PFC) working in fixed OFF time and an inverter composed of a full bridge that drives the lamp at low frequency square wave. The components include a PFC driver, half-bridge drivers, a microcontroller, an auxiliary power supply, a voltage reference, logic parts, an amplifier, comparators, power devices as Power MOSFETs, IGBTs, and fast diodes.

Herein this file you will find detail information regarding 250 W HID lamp description, general circuit description, board description, L6385 high-voltage high and low side driver, ST7LITE39 microcontroller (application pin), auxiliary power supply, TS272 high-performance CMOS dual operational amplifiers, LM119 high-speed dual comparators, 74AC00 QUAD2-input NAND gates, lamp data, PFC section design criteria, full bridge design criteria, experimental results, firmware flowchart, references, and revision history.

Get detail information about Circuit Diagram for 250 W HID Metal Halide Electronic Ballast here – http://www.st.com/stonline/books/pdf/docs/14622.pdf – free download PDF file.

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