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Index 1502

Phone busy indicator circuit2

Published:2011/7/6 19:58:00 Author:zj | Keyword: Phone busy indicator

Phone busy indicator circuit2
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Telephone volume control circuit

Published:2011/7/20 2:34:00 Author:zj | Keyword: Telephone, volume control

Telephone volume control circuit
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Long distance telephone ringing circuit

Published:2011/7/20 2:35:00 Author:zj | Keyword: Long distance, telephone ringing

Long distance telephone ringing circuit
When voltage ofringing circuit is more than 100 V , the two neon light H1 and H2 will be lighted.The output signal will add to VT1、VT2 after rectifiering by VD1~VD4.Then it will add to Optoelectronic coupler IC1,control theconduction of TRIAC.Thus the ac voltage can be added to the socket J, the load will access ac voltagethrough the plug. (View)

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LCl82 audio voltage control neon light pattern control circuit

Published:2011/5/10 7:41:00 Author:Nicole | Keyword: audio voltage control, neon light pattern

LCl82 audio voltage control neon light pattern control circuit
The control circuit is as shown. It consists of pickup sensor, sound control integrated circuit IC1, LC182 light control circuit, AC solid state relay and neon light drive circuit, AC depressurization rectifier circuit. Sensor BM is CRZ2 electret condenser microphone, it will transform the piched up sound singal into electrical signal. IC2 adopts special sound control integrated circuit BH-SK-II. Its chip contains three-level amplifier, shaper, frequency selection network, bistable trigger and drive circuit. The singal from sensor BM is added to input terminal 1 foot of SK-Ⅱsecond level amplifier through C1, after enlarged, it is outputed by 2 foot, and coupled to the input terminal 3 foot of SK-Ⅱthird level amplifier, it is enlarged and shaped again, it is fliped by triggering bistable state. SK-Ⅱhas two drive output terminals of 6 foot, 9 foot, it only uses output current terminal 9 foot as output. Outputed by SK-Ⅱ, The pulse singal is added to LC182 audio frequency singal input terminal UIN through C6. The sound(such as hand-clapping, beating) singal and the flipping of SK-Ⅱbistable state circuit is controlled by sensor BM, then to control the voltage control oscillator frequency inside SK-Ⅱ, it can realize voltage control to the cycle flashing frequency of color lamp. (View)

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Telephone audio amplification and recording device

Published:2011/6/30 21:51:00 Author:zj | Keyword: Telephone, audio amplification, recording

Telephone audio amplification and recording device
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Telephone repairing reference circuit

Published:2011/6/30 21:51:00 Author:zj | Keyword: Telephone, repairing

Telephone repairing reference circuit
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Electric Water Heater Circuit 01

Published:2011/6/30 21:52:00 Author:zj | Keyword: Electric Water Heater, 01

Electric Water Heater Circuit 01
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PC infrared remote control

Published:2011/6/30 21:52:00 Author:zj | Keyword: PC, infrared, remote control

PC infrared remote control
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Thermal furnace temperature regulating circuit

Published:2011/5/9 8:59:00 Author:Nicole | Keyword: furnace, temperature regulating

Thermal furnace temperature regulating circuit
In general regulating circuit, the waste heat sensor is used as voltage divider, it is hard to obtain good linear relationship. The figure (a) may have linear relationship. A few waste heat devices can be controlled by a external control device, then it will produce a DC voltage which has relation with external condition, the value is between 0.91~1.43V. In figure (a), the input terminal 2 switch voltage U7 of operational amplifier OP2 is controlled by the attenuation ratio: RP3+R6/R7, it is about 0.91V, when the control voltage Us=0. The figure (b) is a performance curve of circuit. When control voltage Us≦0.91V, hysteresis loop is about 20%, because the resistance R7 is in action in this region. (View)

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High limit of temperature animal bleating alarm and automatic ventilation cooling control circuit

Published:2011/5/16 3:50:00 Author:Nicole | Keyword: temperature, bleating alarm, ventilation cooling

High limit of temperature animal bleating alarm and automatic ventilation cooling control circuit
The circuit is as shown, it consists of upper temperature limit detection circuit, call alarm circuit, relay control fan lowering temperature circuit and AC depressurization power supply circuit. IC1 adopts CMOS large scale language integrated circuit KD-56021, it stores four kinds of animal sounds: sheep, cattle, chicken, dog. (View)

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PC mainboard circuit 430TX_03

Published:2011/7/6 19:57:00 Author:zj | Keyword: PC mainboard

PC mainboard circuit 430TX_03
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PC mainboard circuit 430TX_02

Published:2011/7/6 19:57:00 Author:zj | Keyword: PC mainboard

PC mainboard circuit 430TX_02
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PC mainboard circuit 430TX_01

Published:2011/7/6 19:57:00 Author:zj | Keyword: PC mainboard

PC mainboard circuit 430TX_01
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Full-bridge power convertor circuit diagram with increase output power

Published:2011/5/5 7:24:00 Author:Nicole | Keyword: Full-bridge power convertor

Full-bridge power convertor circuit diagram with increase output power
The two electrolytic capacitors of half-bridge converter circuit are changed to the other two high back pressure power transistors, and coupled with appropriate drive circuit then canformfull-bridge converter circuit, the figure is as shown. VT1, VT2, VT3, VT4 form 4 bridge arms. High frequency transformer T is connected between them. Relative VT1, VT4 and VT2, VT3 areinspired by the drive circuit, then theyturns onalternately, the DC input voltage into a high-frequency square-wave transform AC voltage. The course of working is the same as push-pull power converter circuit. Thus, when the high frequency transformer at work, the voltage of primary coil is considered to the supply voltage, it isone time ofthe half-bridge circuit output voltage, the pressure of each transistor remains at the supply voltage, twice the output power increases. If the current reaches half-bridge circuit, that means the current increases twice, then the output power can increase 4 times. The main disadvantages of full-bridge circuit is that it needs 4 groups transistor base drive circuits which are insulative with each other, it enlarges the cost and complicates the control drive circuit. (View)