Spy Camera Solar Power Box

Battery life has always been a critical consideration for most of the electronic gadgets and equipment. When we talk about spy  cameras,  which  normally  function  round-the-clock, they often run out of power within a few days.  Many spy cameras (CCTV cameras) are powered by 9V PP3 type batteries that offer five times more energy  than the regular 9V alkaline battery.

Mini CCTV cameras also accept 6-12V DC supply from AC mains adaptor through the DC IN jack. AC mains adaptor for the camera increases the capacity of the 9V PP3 battery but is bulky and noisy. Whether disposable  or rechargeable batteries, making frequent replacement or recharging them is a cumbersome job. The unique solar power box described here serves an alternative solution to the problem. 

Spy Camera Solar Power Box Circuit diagram :

The circuit of the solar power box is simple. It contains a  battery charger and a battery health indicator and  a few other components.  As shown in the circuit,  DC supply available from  the solar panel (SP1) is  directly applied to the in-put of the circuit through  a protection diode (D1).  This diode is used to pre-vent  the  reverse  current  flow from the battery to  the  solar  panel  during  night. Thus, D1 allows  the current to flow from the solar panel  to the battery only. Low-voltage-drop  type 1N5817 diode is perfect for the  job.

At the heart of the circuit is an integrated current source, realised using a  popular 3-pin adjustable voltage regulator LM317T(IC1). 

This IC is designed  to adjust its internal resistance between  the In (pin 3) and Out (pin 2) terminals  to maintain a constant voltage of 1.25V  between the Out (pin 2) and Adj (pin 1) terminals. Here, a 9V, 280 mAh  rechargeable PP3 type Ni-MH battery  (BATT) is used as reservoir. Normally,  a charging current of about 10 per cent  of  ampere-hour  rating  is  safe  for  the  battery. Resistor R1 (39-ohm, 0.5W),  connected between pin 1 and 3 of IC1,  limits  the  charging  current  to  about  30 mA. DC output from the battery is  available at output jack J2. Red LED  ( LED1) is used as a battery ‘health’  indicator. Switch S1 is used to start the  charging while S2 is used for connect-ing the load. Note that suitable heat  sink should be used for the IC1.

The proper selection of solar panel  is important but not critical. A miniature 12V type solar panel with a cur-rent output of about 100 mA can be  used. Even if you have a solar panel  with  higher  voltage  rating,  it  will  not  create a problem as the circuit ensures  that the charging current cannot exceed  the predetermined value.

The circuit can be easily assembled  on a general-purpose PCB and housed  in a small plastic cabinet.

Source :  http://www.ecircuitslab.com/2012/05/spy-camera-solar-power-box.html

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Switch Selected Fixed Voltage Power Supply Circuit Diagram

This Switch Selected Fixed Voltage Power Supply Circuit Diagram can serve as a battery eliminator for various devices (such as tape recorders, small radios, clocks, etc.). Si selects a resistance that is predetermined to provide a preselected output voltage. In this circuit, various commonly used supply voltages produced by batteries were chosen, but any voltages up to the rating of Tl (approximately) can be produced by choosing an appropriate resistor. Remember to provide adequate heatsinking for Ul.

Switch Selected Fixed Voltage Power Supply Circuit Diagram

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High Power Car Battary Eliminator

To operate car audio (or video) system from household 230V AC mains supply, you need a DC adaptor. DC adaptors available in the market are generally costly and supply an unregulated DC. To overcome these problems, an economical and reliable circuit of a high-power, regulated DC adaptor using reasonably low number of components is presented here.  Transformer X1 steps down 230V AC mains supply to around 30V AC, which is then rectified by a bridge rectifier comprising 5406 rectifier diodes D1 through D4. The rectified pulsating DC is smoothed by two 4700μF filter capacitors C1 and C2. The next part of the circuit is a seriestransistor regulator circuit realised using high-power transistor 2N3773 (T1).

 

Fixed-base reference for the transistor is taken from the output pin of 3-pin regulator IC1 (LM 7806). The normal output of IC1 is raised to about 13.8 volts by suitably biasing its common terminal by components ZD1 and LED1. This simple arrangement provides good, stable voltcuit age reference at a low cost. LED1 also works as an output indicator.Finally, a crowbar-type protection circuit is added. If the output voltage exceeds 15V due to some reason such as component failure, the SCR fires because of the breakdown of zener ZD2. Once SCR fires, it presents a short-circuit across the unregulated DC supply, resulting in the blowing of fuse F1 instantly. This offers guaranteed protection to the equipment connected and to the circuit itself.

 

This circuit can be assembled using a small general-purpose PCB. A goodquality heat-sink is required for transistor T1. Enclose the complete circuit in a readymade big adaptor cabinet as shown in the figure.

Source:  http://www.ecircuitslab.com/2011/09/high-power-car-battary-eliminator.html

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Best Power Protection Circuit Diagram

This is the Best Power Protection Circuit Diagram for you. (Read Power supply Protection Circuit Diagram ) To safeguard portable, emergency power repeaters from reverse or excessive voltage, Dl prevents incorrect polarity damage, and zener voltage determines the maximum voltage that will reach the rest of the circuitry. Use fast blowing fuse rated greater than the SCR current rating.

Read: Over voltage Protection Circuit Diagram

Best Power Protection Circuit Diagram

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How to Build a Simple Power supply Circuit Diagram

To day i share this post how to Build a simple power-supply circuit diagram lets start . This simple power supply circuit diagram delivers plus and minus 9 V to replace two 9-V batteries. The rectifier circuit is actually two separate full-wave rectifiers fed from the secondary of the transformer. One full-wave rectifier is composed of diodes D1 and D2, which develop +9 V, and the other is composed of D3 and D4, which develop -9 V. 

Each .diode from every pair rectifies 6.3 Vac, half the secondary voltage, and charges the associated filter capacitor to the peak value of the ac waveform, 6.3 x 1.414 ~ 8.9 V. Each diode should have a PIV, Peak Inverse `Voltage, rating that is at least twice the peak voltage from the transformer, 2 x 8.9 ~ 18 V. The 1N4001 has a PIV of 50 V. I hope you are enjoy this circuit.

Simple Power supply Circuit Diagram

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500W Mos Fet Power Inverter from 12V to 110V 220V

This circuit will provide a very stable "Square Wave" Output Voltage. Frequency of operation is determined by a pot and is normally set to 60 Hz. Various "off the shelf" transformers can be used. Or Custom wind your own FOR BEST RESULTS. Additional MosFets can be paralleled for higher power. It is recommended to Have a "Fuse" in the Power Line and to always have a "Load connected", while power is being applied. The Fuse should be rated at 32 volts and should be approximately 10 Amps per 100 watts of output. The Power leads must be heavy enough wire to handle this High Current Draw!

Appropriate Heat Sinks Should be used on the RFP50N06 Fets. These Fets are rated at 50 Amps and 60 Volts. ** Other types of Mosfets can be substituted if you wish. The LT1013 offers better drive that the LM358, but its your choice. The Power transformer must be capable of handling the chosen wattage output. Also, Appropriate Heat Sinks are Necessary on the Mos-Fets. Using a rebuilt Microwave transformer as shown below, it should handle about 500 watts Maximum. It requires about 18 turn Center-Tapped on the primary. To handle 500 watts would require using a 5 AWG wire. Pretty Heavy Stuff, but so is the current draw at that power.

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Power Resumption Alarm and Low Voltage Protector

The circuit described here protects your electrical appliances like AC motors from damage due to low voltage at power-on. It remains standby without giving power to the load after power resumes. The load can be switched on only manually. This prevents damage to the device if it is on when power resumes.

unregulated power supply is derived from a 12V-0-12V, 300mA step-down transformer and rectifying diodes D2 and D3. The rectified DC is made ripple-free using capacitor C3. An audio/video indicator (piezobuzzer and LED3) is provided along with the power supply for power resumption.

When power is switched on, capacitor C4 charges through the piezobuzzer and LED3, making both of them active. The piezobuzzer beeps and LED3 glows for a few seconds. When capacitor C4 is fully charged, the cathode of the LED becomes high inhibiting further flow of current through the buzzer.

When the power is off, capacitor C4 discharges through resistor R9.

The circuit uses IC CA3140 (IC1) as a voltage comparator to detect voltage changes in the unregulated power supply due to AC mains. Mains voltage changes in the primary as also the secondary winding of the transformer, which is sensed by IC1 to energise/de-energise the relay. Zener diode ZD1 provides a reference voltage of 3V to make transistor T1 conduct. Preset VR1 adjusts the breakdown point of ZD1.

Fig. 1: Power supply circuit with resume indicator

When the voltage level is normal, zener diode ZD1 breaks down and transistor T1 is forward-biased. Capacitor C1 provides time delay of a few seconds to avoid any fluctuation affecting the device during power-on. When transistor T1 conducts, the inverting input (pin 2) of IC1 goes low. However, IC1 does not give a high output as its power supply depends on the conduction of SCR1 (BT169). So manual operation is necessary to energise the relay.

When push-to-on swish S1 is pressed, SCR1 fires to provide voltage to IC1 at its pin 7. As the voltage level at the non-inverting input (pin 3) of IC1 is half of the supply voltage, its output becomes high and the relay (RL1) energises. LED2 glows to indicate the high output of IC1 and activation of relay.

When the line voltage goes below 180V, the secondary voltage of the transformer also drops, say, below 12 volts, ZD1 cease to conduct and the collector of T1 becomes high. This high voltage at the inverting input (pin 2) of IC1 makes its output low. The relay de-energises to stop power to the device.

Fig. 2:  Low-voltage Protector Circuit Diagram

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Use a 12V PCB-mounted relay. Provide holes for LEDs and switch S1 on the front side of the case. Connect AC power voltage to the motor (load) through the common and normally-open (N/O) contacts of the relay. After assembly and checking the circuit, switch on the circuit and wait for a few minutes. LED1 will gradually become bright due to the charging of capacitor C1. Press S1 to energise the relay. Adjust VR1 so as to make LED1 fully on. This will allow easy latching of the relay.

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High Power Alarm Driver

In this circuit, a low-powered SCR is used to trigger a higher powered SCR. When a switch is opening (S2, S3, S4) or closing (S5, S6, S7), either SCR1 or SCR2 triggers. This triggers SCR3 via D1, D2, and R5. BZ1 is a high-powered alarm of the noninterrupting type. 

High-Power Alarm Driver Circuit Diagram

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100Khz Multiple Output Switching Power Supply Circuit Diagram

The 100Khz Multiple Output Switching Power Supply Circuit Diagram uses two VN4000A 400-V MOSPOWER FETs in a half-bridge power switch configuration. Outputs available are + 5 Vat 20 A and ±15 V (or ±12 V) at 1 A. Since linear three-terminal regulators are used for the low-current outputs, either ±12 V or ±15 V can be made available with a simple change in the transformer secondary windings. 

A TU94 switching regulator IC proVides pulse-width modulation control and drive signals for the power supply. The upper MOSPOWER FET, Q7. in the power switch stage is driven by a simple transformer drive circuit. The lower MOS. Q6, since it is ground referenced. is directly driven from the control !C.

 100Khz Multiple Output Switching Power Supply Circuit Diagram

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Constructing your own Dual Power Supply Rise

Many times the hobbyist desires to have a simple, dual power supply for a project. Existing power supplies may be large either in power output or physical size. a simple Dual Power Supply is necessary.For most non-critical applications the best & simplest choice for a voltage regulator is the 3-terminal type.The three terminals are input, ground & output.

The 78xx & 79xx series can provide up to 1A load current & it have on chip circuitry to prevent damage in the event of over heating or excessive current. That is, the chip basically shuts down than blowing out. These regulators are cheap, simple to make use of, & they make it practical to design a method with plenty of P C Bs in which an unregulated supply is brought in & regulation is done locally on each circuit board.

This Dual Power Supply project provides a dual power supply. With the appropriate choice of transformer & 3-terminal voltage regulator pairs you can basically build a tiny power supply delivering up to amp at +/- 5V, +/- 9V, +/- 12V, +/-15V or +/-18V. You require to provide the middle tapped transformer and the 3-terminal pair of regulators you require:7805 & 7905, 7809 & 7909, 7812 & 7912, 7815 & 7915or 7818 & 7918.

The user must pick the pair they needs for his particular application.

Note that the + & - regulators do not must be matched: you can for example, use a +5v & -9V pair. However,the positive regulator must be a 78xx regulator, & the negative a 79xx. They have built in plenty of safety in to this project so it ought to give plenty of years of continuous service.

Transformer
This Dual Power Supply design makes use of a full wave bridge rectifier coupled with a centre-tapped transformer. A transformer with a power output rated at at least 7VA ought to be used. The 7VA rating means that the maximum current which can be delivered without overheating will be around 390mA for the 9V+9V tap; 290mA for the 12V+12V and 230mA for the 15V+15V. If the transformer is rated by output RMS-current then the worth ought to be divided by one.2 to get the current which can be supplied. For example, in this case a 1A RMS can deliver 1/(one.2) or 830mA.

Rectifier

They use an epoxy-packaged four amp bridge rectifier with at least a peak reverse voltage of 200V. (Note the part numbers of bridge rectifiers are not standardised so the number are different from different manufacturers.) For safety the diode voltage rating ought to be at least to times that of the transformers secondary voltage. The current rating of the diodes ought to be two times the maximum load current that will be drawn.

Filter Capacitor
The purpose of the filter capacitor is to smooth out the ripple in the rectified AC voltage. Theres dual amount of ripple is determined by the worth of the filer capacitor: the larger the worth the smaller the ripple.The two,200uF is an appropriate value for all the voltages generated using this project. The other consideration in choosing the correct capacitor is its voltage rating. The working voltage of the capacitor has to be greater than the peak output voltage of the rectifier. For an 18V supply the peak output voltage is one.4 x 18V, or 25V. So they have selected a 35V rated capacitor.

Regulators

The unregulated input voltage must always be higher than the regulators output voltage by at least 3V in order for it to work. If the input/output voltage difference is greater than 3V then the excess potential must be dissipated as heat. Without a heat sink three terminal regulators can dissipate about two watts. A simple calculation of the voltage differential times the current drawn will give the watts to be dissipated. Over two watts a heat sink must be provided. If not then the regulator will automatically turn off if the internal temperature reaches 150oC. For safety it is always best to make use of a small heat sink even in case you do not think you will need.

Stability

C4 & C5 improve the regulators ability to react to sudden changes in load current & to prevent uncontrolled oscillations.

Decoupling

The mono block capacitor C2 & C6 across the output provides high frequency decoupling which keep the impedance low at high frequencies.

LED

Two LEDs are provided to show when the output regulated power is online. You do not must make use of the LEDs in the event you do not require to. However, the LED on the negative side of the circuit does provide a maximum load to the 79xx regulator which they found necessary in the coursework of testing. The negative 3-pin regulators did not like a zero load situation. They have provided a 470R/0.5W resistors as the current limiting resistors for the LEDs.

Diode Protection

These protect chiefly against any back emf which may come back in to the power supply when it supplies power to inductive lots. They also provide additional short circuit protection in the case that the positive output is connected by accident to the negative output. If this happened the usual current limiting shutdown in each regulator may not work as intended. The diodes will short circuit in this case & protect the two regulators.

Dual Power Supply Schematic Diagram

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TBA820 low power audio amplifier

At this time amplifier circuit based on IC KA2201, TBA820M, LM820M, and U820. You can use all ic is the series under the scheme. This amplifier circuit has a very small output power or low at 2W. Required supply voltage from 3 volts to a maximum of 16 volts.

Below is a scheme of this power amplifier

Part List

R1 = 100K

R2 = 120R

R3 = 100R

C1 = 100nF

C2 = 100uF
C3 = 470uF
C4 = 220pF

C5 = 47uF

C6 = 100uF

IC = KA2201 , LM820M , TBA820M , U820M

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100 Watt Power Amplifier Circuit With IC TDA7294

Power Amplifier TDA7294 is a power amplifier with IC Power Amplifier is a mono 100W Class AB operation of OCL.

The power supply circuit. Positive, negative, and ground. Usually, we use the power supply circuit to + /-25V to + /-35V at 100W RMS will be used to heat sufficiently.

After many members have already made the TDA7294 as I know, with a sound quality that is the very gods or Hi-End itself.

Several days before the member’s PM to me saying that I had an amplifier using IC TDA7294 to have more of the same. Higher power. And low heat.

Achieved by increasing the voltage raising circuit For the more, it means high power and high heat up. Today I have come across. I use IC TDA7294 circuit at the time.

In-Home Use amplifier circuit is a Class G amplifier with low power consumption, resulting in the loss of a 20V DC power less.

And when you’re driving a high-power random access is party to a rhythm. Principles to do it. I took out a membership you can do is try to build up a bit.

We provides PCB both top and bottom side for you.

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Simple 0 30 Volts 2 5A Variable Power Supply Circuit Diagram

This is the Simple 0-30 Volts - 2-5A Variable Power Supply Circuit Diagram. This is a high quality power supply with a continuously variable stabilized output adjustable between 0 and 30VDC. the LM 723 is the heart of the power supply which drives the BD137 and then the 2N3055. The circuit provides short circuit protection. And has great stability at voltage changes. Drive the circuit with 24 Volts 3A from a transformer. the 2N3055 needs a good heat sink.

  0-30 Volts - 2-5A Variable Power Supply Circuit Diagram

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0 30 Volt Power Supply

linear power supply, shown in the schematic, provides 0-30 volts, at one amp, maximum, using a discrete transistor regulator with op amp feedback to control the output voltage. The supply was constructed in 1975-6 & has a constant current mode that is used to recharge batteries.

With reference to the schematic, lamp, LP2, is a power on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, & Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zen-er across C2 limits the maximum supply voltage to the op amps supply pins. D5, C4, C5, R15, & R16 provide a tiny amount of negative supply for the op amps so that the op amps can operate down to zero volts at the output pins (pins 6). A more modern design might eliminate these four parts & use a CMOS rail-to-rail op-amp. Current limit is set by R3, D1, R4, R6, Q12, R10, & R13 providing a bias to U2 that partially turns off transistors Q9 & Q11 when the current limit is reached. R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), & R11 is an internal trim-pot for calibration. The meter is a one milliamp meter with an internal resistance of 40 ohms. Switch S1 determines whether the meter reads 0-30 volts, or 0-1 amp.

A more new circuit might use a single IC regulator, such as the MC78XX, or MC79XX series, immediately after the half wave rectifier, to replace about 30 parts, or at least a high precision zen-er diode to replace D10 as the voltage reference. The LM4040 is such voltage reference & has excellent stability over temperature. IC regulators such as the MC78XX series may finally become obsolete as newer IC regulators are designed, however, discrete transistors, op-amps, & zeners are more generic, have an extended production lifespan, & permit the designer to demonstrate that they understands the principles of linear regulated power supply operation.

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High Voltage 3 Watt Audio Power Amplifier Circuit

The LM4954 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 2.4 Watts of continuous average power to an 8 BTL load with less than 1% THD+N from a 7V_DC power supply.

Boomer audio power amplifiers are designed specifically to provide high quality output power with a minimal number of external components. The LM4954 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for lower-power portable applications where minimal space and power consumption are primary requirements.

Circuit   Diagram:

 High Voltage 3 Watt Audio Power Amplifier Circuit Diagram

The LM4954 features a low-power consumption global shutdown mode which is achieved by driving the shutdown pin with logic low. Additionally, the LM4954 features an internal thermal shutdown protection mechanism.

The LM4954 contains advanced pop & click circuitry which eliminates noises that would otherwise occur during turn-on and turn-off transitions.

The LM4954 is unity-gain stable and can be configured by external gain-setting resistors.

Key Specification:

Wide Power Supply Voltage Range	2.7 <= VDD <= 9V
Output Power: VDD = 7V, 1% THD+N	2.4W (typ)
Quiescent power supply current	3mA (typ)
PSRR: VDD = 5V and 3V at 217Hz	80dB (typ)
Shutdown power supply current	0.01µA (typ)

 

Features:

No output coupling capacitors, snubber networks or bootstrap capacitors required

Unity gain stable

Externally configurable gain

Ultra low current active low shutdown mode

BTL output can drive capacitive loads up to 100pF

"Click and pop" suppression circuitry

2.7V - 9.0V operation

Available in space-saving microSMD package

Applications

Mobile Phones

PDAs

Source:national

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Stereo Power Amplifier Circuit based on BA5417

BA5417 is a stereo amplifier IC with a lot of good features like thermal shut down, standby function, soft clipping, wide operating voltage range etc. The IC can deliver 5W per channel into 4 ohm loud speakers at 12V DC supply voltage. The BA5417 has excellent sound quality and low THD (total harmonic distortion) around 0.1% at F=1kHz; Pout=0.5W.

Stereo Power Amplifier  Circuit diagram :

Setup and working of this stereo power amplifier circuit is somewhat similar to the BA5406 based stereo amplifier circuit published previously. C10 and C11 are DC decoupling capacitors which block any DC level present in the input signals. C2 and C6 couples the amplifiers left and right power outputs to the corresponding loud speakers. C1 and C5 are bootstrap capacitors.

Bootstrapping is a method in which a portion of the amplifiers is taken and applied to the input. The prime objective of bootstrapping is to improve the input impedance. Networks R1,C3 and R2,C7 are meant for improving the high frequency stability of the circuit. C4 is the power supply filter capacitor. S1 is the standby switch. C8 is a filter capacitor. R3 and R4 sets the gain of the left and right channels of the amplifier in conjunction with the 39K internal feedback resistors.

Note :

• Supply voltage range of BA5417 is from 6 to 15V DC.
• The recommended supply voltage for this circuit is 12V DC.
• The power supply must be well regulated and filtered.
• BA5417 requires a heatsink.
• The circuit can be assembled on a perf board without much degradation in performance.

Source : http://www.ecircuitslab.com/2012/07/stereo-power-amplifier-circuit-based-on.html

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Simple split power supply circuit Diagram

This circuit utilizes the quasi-complementary output stage of the popular LM380 audio power IC. The device is internally biased so that with no input the output is held midway between the supply rails Rl, which should be initially set to mid-travel, is used to nullify any inbalance in the output. 

Regulation of Vout depends upon the circuit feeding the LM380, but positive and negative outputs will track accurately irrespective of input regulation and unbalanced loads. 

The free-air dissipation is a little over 1 watt, and so extra cooling: may be required. The device is fully protected and will go into thermal shutdown if its rated dissipation is exceeded. Current limiting occurs if the output current exceeds 1 A. The input voltage should not exceed 20 V.

Simple split power supply circuit Diagram

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Panasonic Microwave Oven Inverter HV Power Supply

Nearly all Panasonic microwave ovens now use an Inverter, and are always labelled with “Inverter” on
the front.

The High Voltage Power Supply Unit (HV PSU)

The HV PSU measures 165mm x 105mm x 60mm and weighs 650g.

 At left is the control daughter board. In front of that on the main board are the opto-isolators for the control and status signals brought out to the green connector. Back left is the rectified mains filter choke. The mains rectifier and switching transistors can just be seen on the heatsink behind the transformer. The mains filter capacitor is at right rear. The HV rectifiers and filters (doubler) are right front – white wires are the HV output from the transformer. The green wire is for grounding the HV +ve. The two lugs t right are for connecting HV -ve and heater to the magnetron. The winding thatcan be seen on the transformer is the primary and is made from 3mm finely stranded wire.

Here’s a view of the control end: 

This is the high voltage end:

The circuit for the HV PSU is below 

Notes about the circuit:
1. Apart from the block diagram, there is no information on the Inverter cont(o)rol circuit. The circuit itself is centred on one large, unmarked IC, so no help there.
2. The control and status signals seem to be a digital stream (2-3v suggestsa 5V data stream). They are opto-isolated because the majority of the circuit is at mains potential  (**BEWARE**). The part that isn’t is at 4kV (*** REALLY BEWARE ***)
3. The mains input side is monitored for both current and (under) voltage. No indication of what the control circuit does with this information.
4. The mains filter capacitor (C702) is very small – only 4uF. In a “normal” switching supply, there is usually 220 or 470 uF in this position.
5. Q701 that does all the hard work is a very heavy duty IGBT – a GT60N90 - 900V @ 60 A. Q702 forms some sort of flywheel circuit. This circuit from a Toshiba IGBT application note looks similar:

6. The HV side has a full-wave doubler rectifier and is marked 4kV @  300mA. Unlike the classic microwave oven transformers (where one side of the winding is grounded), this means that the secondary must be well insulated from ground on both sides. A simple reconfiguration of the rectifier (replace the caps with diodes) into a bridge circuit should yield 2kV @ 600mA (depending on the diode ratings)
7. The HV filter capacitors are only 8200 pF each, effectively giving 4100pF in the doubler. Considering that the inverter runs at about 30kHz, the reactance is equivalent to that  of a 5uF capacitor at 50Hz.
8. The positive side of the HV is grounded, so it’s a –4kV supply. Don’t simply swap the ground from the positive to the negative to get a +4kV supply, as the core of the transformer is also connected to this ground trace and will suddenly rise to 4kV above ground with disastrous and potentially fatal results. Instead, reverse the polarity of the rectifier diodes to get +4kV.

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Build a 0 To 12V 1A Variable Power Supply Circuit Diagram

This 0- to 12-Vdc variable power supply uses an IC voltage regulator and a heavy-duty transformer to provide a reliable dc power supply. Looking at the schematic shown, you can sec that transformer Tl has a 120-V primary and a 28-V secondary. Filtered dc is fed to the input (pin 2) of the LM317T voltage regulator, IC, which keeps the voltage at its output constant (pin 3) regardless (within limitations) of the input voltage. 

Pin 1 of the LM317T is the adjustment pin. Varying the voltage on pin 1 (via PI) varies the output voltage. Diodes D5 through D7 and LEDs LI through L3 give an approximate indication of the output voltage. Each LED/diode path has a limiting resistor to limit the current to a level that is safe for the LED. 

 Build a 0 To 12V, 1A Variable Power Supply Circuit Diagram

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Power On Indicator

Some types of electronic equipment do  not provide any indication that they are  actually on when they are switched on.  This situation can occur when the back-light of a display is switched off. In addition, the otherwise mandatory mains  power  indicator  is  not  required  with  equipment  that  consumes  less  than  10 watts. As a result, you can easily forget  to switch off such equipment. If you want  to know whether equipment is still drawing power from the mains, or if you want  to have an indication that the equipment  is switched on without having to modify the equipment, this circuit provides a solution. 

One way to detect AC power current and  generate a reasonably constant voltage  independent of the load is to connect a  string of diodes wired in reverse parallel in series with one of the AC supply  leads. Here we selected diodes rated  at 6 A that can handle a non-repetitive  peak current of 200 A. The peak current  rating is important in connection with  switch-on  currents.  An  advantage  of  the selected diodes is that their voltage  drop increases at high currents (to 1.2 V  at 6 A). This means that you can roughly  estimate the power consumption from  the brightness of the LED (at very low  power levels). The voltage across the diodes serves as  the supply voltage for the LED driver. To  increase the sensitivity of the circuit, a  cascade circuit (voltage doubler) consisting of C1, D7, D8 and C2 is used to double  the voltage from D1–D6. Another benefit  of this arrangement is that both halve- waves of the AC current are used. We use  Schottky diodes in the cascade circuit to  minimise the voltage losses.

Circuit diagram :

Power On Indicator Circuit Diagram

 

The LED driver is designed to operate the LED  in blinking mode. This increases the amount  of current that can flow though the LED when  it is on, so the brightness is adequate even  with small loads. We chose a duty cycle of pproximately 5 seconds off and 0.5 second  on. If we assume a current of 2 mA for good  brightness with a low-current LED and we can  tolerate a 1-V drop in the supply voltage, the  smoothing capacitor (C2) must have a value of  1000 µF. We use an astable multivibrator built around two transistors to implement a  high-efficiency LED flasher. It is dimensioned to minimise the drive current of  the transistors. The average current consumption is approximately 0.5 mA with a  supply voltage of 3 V (2.7 mA when the  LED is on; 0.2 mA when it is off). C4 and  R4 determine the on time of the LED (0.5  to 0.6 s, depending on the supply volt-age). The LED off time is determined by  C3 and R3 and is slightly less than 5 seconds. The theoretical value is R × C × ln2,  but the actual value differs slightly due to  the low supply voltage and the selected  component values.

 

Diodes D1-D6 do not have to be special  high-voltage diodes; the reverse volt-age is only a couple of volts here due  the reverse-parallel arrangement. This  voltage drop is negligible compared to  the value of the mains voltage. The only  thing you have to pay attention to is the  maximum load. Diodes with a higher  current rating must be used above 1 kW.  In addition, the diodes may require cool-ing at such high power levels.  Measurements on D1–D6 indicate that  the voltage drop across each diode is  approximately 0.4 V at a current of 1 mA.  Our aim was to have the circuit give a  reasonable indication at current levels  of 1 mA and higher, and we succeeded  nicely. However, it is essential to use a  good low-current LED.

 

Caution: the entire circuit is at AC power potential. Never work on the circuit with the mains cable plugged in. The  best enclosure for the circuit is a small,  translucent box with the same colour as  the LED. Use reliable strain reliefs for the  mains cables entering and leaving the  box (connected to a junction box, for  example). The LED insulation does not  meet the requirements of any defined insulation class, so it must be fitted such that it  cannot be touched, which means it cannot  protrude from the enclosure. 

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