Circuit Diagram

450 audio signal generator circuit

Published:2011/8/6 8:27:00 Author:nelly | Keyword: audio signal, generator

This oscillator is the signal source of the communication unit users. The working principle is as shown in the picture. It is composed of the VT1, VT2 and the related components. VTl uses the transformer T coupling to generate the oscillator signal, and the VT2 is the buffer amplifier of common collector circuit. T changer 1—4 winding form the frequency selective network. In order to prevent the magnetic saturation, T is connected to the collector of VT| by 1-2 tap, 5-6 of T is the feedback coil. Test: The pin of the every DC potential (reference value) is as shown in the table.   (View)

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Electrical equipment overload and open-phase protection device circuit composed of 555

Published:2011/8/4 20:39:00 Author:Rebekka | Keyword: Electrical equipment overload , open-phase protection device

The device is composed of +12 V, +5 V DC power supply, AC transformer, voltage comparator, block timer, relay control circuit and phase loss protection circuits and other components. LH makes three-phase AC transformer current flowing couple in proportion, and they pass D1C1, D2C2, D3C3 rectifier filters and are added to the voltage comparator (IC1, DW1, DW5, R7) and phase-failure protection circuit (IC4, IC5, IC6). The phase loss protection circuit is composed of IC4 (CD4070), IC5 (7402), IC6 (CD4013). It is used for detecting and determine whether the three-phase current, if a phase-off phase, the IC3 will be set, the relay J Pick-up, the device will be cut off and the phase protection works.   (View)

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Multiplexed output digital camera power supply circuit composed of MAX1802

Published:2011/5/10 1:47:00 Author:Rebekka | Keyword: Multiplexed output digital camera , power supply

Composed of MAX1802 multiple output digital camera power supply circuit diagram is shown as below. MAX1802 Chip has 2 buck converters and 3 boost converters. Input voltage 2.5～11V, continuously adjustable output voltage 2.7～5.5V. The lowest output voltage can be ajdusted to 1.25V. The working rate of MAX1802 can be adjusted to 1MHz and conversion efficiency can up to 94％.   (View)

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Multi-function integrated security device circuit diagram

Published:2011/8/4 20:00:00 Author:Rebekka | Keyword: Multi-function , integrated security device

Leakage detection circuit is composed of the L1, L2, L3, J1 and so on. The J1 is the leakage detection coil, the relay power from the JZ7-44 isconverted. Under normal circumstances, the current size on the L1, L2 are the same. The phases are contrast. There is no leakage voltage signal in L3. When there is electric shock or leakage occurs, the L3 balance will be destroyed due to the magnetic field induces a voltage signal leakage. The security devicecan achieve the functions ofleakage protection, overvoltage and undervoltage protection, automatic reset delay (5 minutes or 30 seconds) and so on.   (View)

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Automatically reset earth leakage protector circuit composed of NE555

Published:2011/8/4 20:03:00 Author:Rebekka | Keyword: earth leakage protector

Signal detection circuit is the zero sequence current transformer composed of L1, L2, L3 and the magnetic core. Under normal circumstances, the total magnetic flux in the transformer is 0. When someone is shocked by the electric, the power supply passes the body to the ground, the current flowing of L1, L2 are different. Zero-sequence transformer in the magnetic flux induced in the L3 has an alternating voltage, and it is rectified by D1 and added to BG's base, so that BG saturated conduction, and 555 feet ois set because of potential ② low (<1 / 3VDo).   (View)

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Automatic power protector circuit composed of 555

Published:2011/8/4 20:03:00 Author:Rebekka | Keyword: Automatic power protector, 555

The figure shows the automatic power protection circuit. The protector is composed of the buck rectifier circuit, overvoltage and undervoltage detection circuit, delay switch control circuit. The buck rectifier circuit provides DC voltage for the entire circuit.   (View)

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Automotive electronic password lock circuit diagram

Published:2011/8/4 21:35:00 Author:Rebekka | Keyword: Automotive electronic password lock

Automotive electronic code lock circuit is shown as above. ICl is exclusive lock for the integrated circuit 5G058, its ① ~ ⑥ feet connect external key switch to the power supply. They are six valid input keys. The unlock must follow the sequence of Sl ~ S6; pin ⑧ button switch S7 is connected to the false key input. It is free to pick one or a few keys on the keyboard plugged in as real mixed; pin⑨ is the key indication side, each key will cause the external connectivity in the light-emitting diode LEDl.   (View)

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Multi-function household electrical appliances protection circuit diagram

Published:2011/8/4 21:34:00 Author:Rebekka | Keyword: household electrical appliances, protection circuit

The circuit is composed of DC circuit, delay circuit, overvoltage and undervoltage protection circuit etc. ICl integrated circuit LM7812 outputs +12 V voltage. Undervoltage and overvoltage sample protection circuit is composed of sampling R2, potentiometer RP2, the regulator DWl, VTl and Rl, RPl, DW2, VT2, VD5, VD6, VT3 and control relay J1. In the figure, VT1 ~ VT3 use 3DG4, thyristor VS uses 6A/400V, VD1 ~ VD7 use 1N4004, relay J1 uses JRC-1M 12V.   (View)

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Funai VIP-3000HCMKIII Type Videoplayer Audio Squelch Control Circuit Working Principle And Repairing Circuit

Published:2011/8/6 19:36:00 Author:Robert | Keyword: Funai, Videoplayer, Audio, Squelch, Control, Working, Principle, Repairing

The Funai VIP-3000HCMKIII type videoplayer audio squelch control circuit is simple, but it has a high fault rate. This arctical intruduces this audio squelch control circuit's working principle and common faults' repairing methdod.Working Principle.This device's audio squelch control circuit is shown in the picture. It is made up of squelch control transistor V4001, VD4001, R16 and system control microprocessor IC01 (A.MUTE) and so on. Its working principle is intruduced here. When inserting a tape and pressing the replay key, the system control microprocessor IC01's pin would output low voltage level. Then the squelch control transistor V4001 is not conducted. The audio magnetic head picks the audio signal from the tape and then output from pin 6 through the IC4001 (BA328)'a pre-equilibrium and amplification.   (View)

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Hangchan HENTR Brand Constant Voltage Power Amplifier No Output Special Fault Repairing Circuit

Published:2011/8/6 8:53:00 Author:Robert | Keyword: Hangchan, HENTR, Constant, Voltage, Power Amplifier, Output, Special, Fault, Repairing

When checking at starting, it finds one of the two 10000uF/100V power filter capacitors is rupturing. So it could only remove the ruptured capacitor and carefully wipe the electrolyte on the circuit board. Then checking the power tube and it is not found the sign of short circuit. At last it replaces a new 10000uF/100V filter capacitor and internal-device 15A fuse. Then trying the device it is all normal. After some days it is found that when starting the relay sometimes could be connected but sometimes it couldn't and also has the alarm sound. It also finds the following law. If firstly starting after shutting off for a long time, the relay could always be connected. And if starting after shutting off for not a long time, the relay could be sometimes connected and sometimes not connected.   (View)

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Jianlong AV320 Power Amplifier Volume Automatically Increasing Repairing Circuit

Published:2011/8/4 10:02:00 Author:Robert | Keyword: Jianlong, Power Amplifier, Volume, Automatically, Increasing, Repairing

Each time it has set the volume at the starting time of the device, the volume would be increasing automatically and slowly until the maximum value. This device's volume control IC's model name is erased, and the volume could be remote controlled and also be controlled by hand. To narrow the repairing faults's range, it could firstly pluck the connection plugin to the remote-control circuit and try the device. If the fault still remains, it proves that the fault is not in the remote-control circuit, and it is in the part of electronic volume control circuit.The electronic volume control circuit TC9153's function pin is the same with it, which is shown in the picture. The signal inputs from pin 5 and pin 12. The pin 2, pin 3, pin 14, pin 15 are connected with 4558 for buffering and amplification. And the signal outputs from pin 6 and pin 11. It uses the pin 9 and pin 10's low voltage level pulse signal to achieve the control of the volume's increasing and decreasing.   (View)

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Aileite ESR-200 Type Satellite Receiver Switch Power Troubleshooting Circuit

Published:2011/8/4 21:24:00 Author:Robert | Keyword: Aileite, Satellite, Receiver, Switch, Power, Troubleshooting

Fault 1: Starting without any instructions.If pressing the power switch, it could hear the switch transformer's normal pulses sound. By testing the output ports' voltage of each group, it is found that they are all just a half of the normal working voltage. By adjusting the VR and testing the IC2's R port's voltage, it could vary between 0.9~1.5V. The the output port K has corresponding variation. But it could achieve the normal value. The IC2's external elements are tested to be normal. Then replace a new IC2, the fault is eliminated. Testing the IC2's R port's voltage again, its result is 2.5V. The K port is 11.3V. By adjusting VR1, The IC2's R port's voltage could vary between 2.1V and 3V, also the output port's voltage has the corresponding variation.   (View)

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MIDI receiving circuit diagram

Published:2011/8/5 1:15:00 Author:Ecco | Keyword: MIDI

Transmission cable uses the shielded twisted pair cable, because the signal transmission uses current signal to replace voltage signal, it has strong anti-interference ability, although its rate is up to 31.5kbps, transmission distance can still reach 15m, which is further than the common the transmission distance of RS-232 interface. General MIDI receiver circuit is shown as below.   (View)

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Shenzhou ST-9900 Type Satellite Receiver Switch Power Repairing Circuit

Published:2011/8/5 0:14:00 Author:Robert | Keyword: Shenzhou, Satellite, Receiver, Switch, Power, Repairing

Fault 1: Starting without any indication on receiver's panel.The faults analysis and processing. Openning the case, according to the experiences it is firstly to test the power's filter capacitor's two ports (47uF/450V). And there is no voltage indication. It means the power are working without rectifier. Using the multimeter resistance stage to test the current-limiting resistor (6R2/5W), the result is infinity. By analysis, the reason caused the current-limiting resistor damaged is just that the filter capacitor, power regulator tube and other elements are broken. Testing the filter capacitor (47uF/450V), it is found that its upside part has been bulging. Then removing this capacitor to test, it is found to have breakdown. Replacing the filter capacitor and the current-limiting resistor, the receiver panel has the normal indication and the fault is soved.   (View)

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Eggs hatching incubator circuit diagram 3

Published:2011/8/5 1:59:00 Author:Ecco | Keyword: Eggs hatching incubator

The eggs hatch incubator circuit is composed of the power supply circuit and temperature control circuit, and it is shown as the chart. Step-down power supply circuit is composed of the capacitor C1, discharge resistor R8, rectifier diode VD, filter capacitor C2 and zener diode VS. Temperature control circuit is composed of resistors R1 ~ R7, potentiometer RP, thermistor RT, transistors V1 ~ V3 and the intergranular tube VT. R1 ~ R8 select the 1/4W metal film resistors or carbon film resistors. RT uses the thermistor with negative temperature coefficient. RP uses the synthetic membrane or precision multi-turn potentiometer.   (View)

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Eggs hatching incubator circuit diagram 2

Published:2011/8/5 1:55:00 Author:Ecco | Keyword: Eggs hatching incubator

The eggs hatch incubator circuit is composed of the power supply circuit and temperature control circuit, and it is shown as the chart. Power supply circuit is composed of the power transformer T, rectifier diodes VD1 ~ VD4, filter capacitor C and zener diode VS. Temperature control circuit consists of resistors RI ~ R5, potentiometer RP, diode VD5, temperature sensor integrated circuit IC, transistor V, Relay K and electric heater EH. R1 ~ R5 select the 1/4W metal film resistors or carbon film resistors. RP uses the small synthetic membrane potentiometer or multi-turn potentiometer. VD1 ~ VD5 select 1N4007 silicon rectifier diodes.   (View)

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Fushida FR960 Satellite Receiver Repairing Circuit

Published:2011/8/5 20:07:00 Author:Robert | Keyword: Fushida, Satellite, Receiver, Repairing

Firstly visually checking the power board, it finds the fuse is burned to be black. The IC2 4N35 (over-voltage protector), IC3 4N35 (voltage regulator control), Q1 C2060, Q5, C1815 (here it is different from the Wanlida device, Q5 is connected between the IC2 and SCR QBT1690 for over-voltage conversion) are all rupturing. Checking in the circuit it is found that the AV input anti-jamming inductive choke L1, 220V rectifier D1, D2, current limiting resistor R7, C4, switching tube Q3 BU508A, R8, R13, D14 3.6V voltage regulator, C9, Q6 SCR BT1690 are damaged. In the back of the power board there are many copper wires are burned to be black and dropping. The printed board are beyond recognition. In the bottom of the power shield iron box it also has the signs of electric shock.   (View)

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Jingtaike 1288, 628 Satellite Receiver CPU Fault Emergency Maintenance Circuit

Published:2011/8/4 19:58:00 Author:Robert | Keyword: Jingtaike, Satellite, Receiver, CPU, Fault, Emergency, Maintenance

1.Using a 6V 4Ah maintenance-free battery to supply the 5V voltage for CPU and memory (shown in the picture) through two 1N4007 diodes for voltage step-down. The supply current is only 10mA, which would let the CPU and memory to work in a long time and keep the predetermined mode permanently. So that when starting again the CPU would not refuse the power supply.2.The power board +5V power supply voltage should be in series with a low-voltage-drop diode (such as 1N4148) and then it is connected to the main board. Otherwise when starting again, the power's +12V and Vcc voltage would be not normal.   (View)

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Gaosineibeier GSR-2001E Digital Satellite Receiver Switch Power Principle And Repairing Circuit

Published:2011/8/6 19:49:00 Author:Robert | Keyword: Gaosineibeier, Digital, Satellite, Receiver, Switch, Power, Principle, Repairing

1.Switch power working principle.(1)The power input part.The L5, L6 and C23, C1 are make up the dual common-mode low-pass filter network. Its function is to inhibit the EMI from the power network. Also it could inhibit the EMI from the switch power itself to ensure the power network is not polluted. This combination has a good inhibiting function for many kinds of high-frequency interfering signal. The D1~D4 and C2 are make up the bridge rectifier filter circuit. The TH1 in the picture is a thermistor element with negative temperature coefficient. Its feature is that its resistance value would be large when the temperature is low, and its resistance value is low when the temperature is high.   (View)

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Electric steam iron temperature controller

Published:2011/8/5 2:04:00 Author:Ecco | Keyword: Electric steam iron , temperature controller

The electric steam iron temperature controller circuit is composed of the power supply circuit, water level detection circuit, temperature detection circuit and control implementation circuit, and it is shown in Figure 3-82. Power supply circuit is composed of the power transformer T, rectifier diodes VDl-VD4, resistor Rl, power indicator LED VLl, filter capacitors Cl-C4 and three-terminal voltage regulator integrated circuit ICl. Water detection circuit is composed of the the Nl which is inside of the operational amplifier integrated circuit IC2 (Nl, N2), transistor Vl, light-emitting diode VL2, resistors R2, R3, R5-R7, and the water level detection electrodes.   (View)

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