Published:2009/6/24 3:21:00 Author:May
The HEXFET can switch dc power to relays (as shown in A),motors,lamps,and numerous otherdevices That arrangement can even be used to switch resistors in and out ofa circuit,as shown in Fig.88-18B R1,R2,and R3 are possible load resistors and representload configurations that can be used (View)
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Published:2009/6/24 3:22:00 Author:Jessie
These circuits will cure problems caused by switch-contact bounce. The one shown in Fig.88-21A provides you a positive output pulse, and the one shown in Fig. 88-21B provides you a neg-ative output pulse. (View)
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Published:2009/6/24 3:22:00 Author:Jessie
The audio-controlled switch combines a pair of 741 op amps, two 2N222 general-purpose tran-sistors, a HEXFET, and a few support components to produce a circuit that can be used to turn on a tape recorder, a transmitter, or just about anything using sound. (View)
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Published:2009/6/24 3:18:00 Author:May
This timed switch circuit can be usedwhere a timed power Source IS needed,The on-time is approximately 4.6RC (View)
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Published:2009/6/24 3:17:00 Author:May
A combination of series and shunt switching, like that shown between the input and output when in the off condition. (View)
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Published:2009/6/24 3:17:00 Author:May
This transceiver's transmit/receive switch uses PIN-diode instead of a relay. On receive, D1 is cut off, D2 is cut off and the antenna connects to the receiver. During transmit, D1 is forward-biased, as is D2. This connects the receiver input. This causes the input impedance of the transmission line to be high, so little transmitter power reaches the receiver. Although not shown in the schematic, the 12-V supply should have a series resistor of 100Ω to 2.2kΩ, depending on diode current, to limit diode current to a safe value. (View)
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Published:2009/6/24 3:16:00 Author:May
This PIN diode switch uses RF chokes and a single diode。R1 is typically 470Ω to 2.2kΩ (View)
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Published:2009/6/24 3:13:00 Author:May
This circuit uses resistors instead of RE chokes to keep costs low. The values of R1 and R2 should be no lower than about 1 kΩ to minimize loss. (View)
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Published:2009/6/24 3:13:00 Author:May
A bridge rectifier provides pulsating dc to a universal motor, and the SCR is used as a phase-con-trolled switch. This circuit allows smoother operation of the motor at low speeds. (View)
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Published:2009/6/24 3:13:00 Author:May
Eight-band receiver front-end selection can be accomplished by using PIN diode switches (View)
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Published:2009/6/24 3:12:00 Author:May
This PlN-diode switching circuit directs sig-nals to ground when D1 is forward-biased. R1 is Lypically 470Ω to 2.2kΩ. C1 = C2 =0.1μF. (View)
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Published:2009/6/24 3:11:00 Author:May
This design takes advantage of the strobed output stage of a CA3140 amplifier. With the strobing capability, the circuit's output voltage can be set to either of the input voltages by grounding one of the control inputs, either A or B.When the strobe input at pin 8 is taken below 1V, that amplifier is disabled. The remaining am-plifier then acts as a unity-gain high-impedance buffer.The 10-kΩ output resistor enables the output voltage to swing down to 20 mV from ground. The Zener-diode clamps and associated resistors connected at the strobe inputs can be omitted for the lowest-cost applications. However, experience has shown that they allow the amplifiers to shrug off the effect of high transient voltages.The circuit is particularly suited to 8-bit microcontroller applications, where the strobe inputs can be driven directly from two open-collector output ports under software control.The use of Schottky diodes for Dl and D2 makes possible an output swing of 2.5 V when the circuit is powered from a 5-V supply. (View)
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Published:2009/6/24 3:17:00 Author:Jessie
A combination of series and shunt switching, like that shown between the input and output when in the off condition. (View)
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Published:2009/6/24 3:17:00 Author:Jessie
This transceiver's transmit/receive switch uses PIN-diode instead of a relay. On receive, D1 is cut off, D2 is cut off and the antenna connects to the receiver. During transmit, D1 is forward-biased, as is D2. This connects the receiver input. This causes the input impedance of the transmission line to be high, so little transmitter power reaches the receiver. Although not shown in the schematic, the 12-V supply should have a series resistor of 100Ω to 2.2kΩ, depending on diode current, to limit diode current to a safe value. (View)
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Published:2009/6/24 3:16:00 Author:Jessie
This PIN diode switch uses RF chokes and a single diode。R1 is typically 470Ω to 2.2kΩ (View)
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Published:2009/6/24 3:16:00 Author:Jessie
An SCR is used in a phase-control type application to supply a variable pulsating dc voltage to a motor. (View)
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Published:2009/6/24 3:15:00 Author:Jessie
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Published:2009/6/24 3:10:00 Author:May
Here is the schematic of a solid-state ac relay with zero-crossing. The triac permits the relay to switch to ac directly. (View)
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Published:2009/6/24 3:14:00 Author:Jessie
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Published:2009/6/24 3:13:00 Author:Jessie
This circuit uses resistors instead of RE chokes to keep costs low. The values of R1 and R2 should be no lower than about 1 kΩ to minimize loss. (View)
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