Circuit Diagram

Wide_band_high_crest_factor_PMS_to_DC_converter_using_an_AD534_multiplier_divider_chip

Published:2009/7/20 3:47:00 Author:Jessie

Wide-band high-crest-factor PMS-to-DC converter using an AD534 multiplier/divider chip (courtesy Analog Devices, Inc.).   (View)

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IR_REFLECTION_PROXIMITY_SWITCH

Published:2009/7/9 20:50:00 Author:May

IR radiation from LED2 (modulated by a 1-kHz wave) is keyed by U1, and Q1 is radiated. Reflected IR energy is picked up by Q3, and the audio signal from Q3 is amplified by Q2 and sent to the decoder. The LED1 lights to indicate presence of reflected IR. LED1 can be the input of an isolator so that a triac or SCR can be controlled.   (View)

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Differential_input_voltage_to_frequency_convener_using_an_AD534_multiplier_divider_chip_

Published:2009/7/20 3:46:00 Author:Jessie

Differential-input voltage-to-frequency convener using an AD534 multiplier/divider chip (courtesy Analog Devices, Inc.).   (View)

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pH_PROBE_AND_DETECTOR

Published:2009/7/9 20:50:00 Author:May

The greatest sensitivityis achieved if R1 is approximately equal to the probe resistance．The circuitcan be zeroed with R2,while the full-scale voltage is controlled by R5. The correlation between pH andoutput voltage might not be linear, which would necessitate a shaping circuit. A calibration scheme, using solutions of known pH, might prove adequate and more reliable over a period of time because of probe vanance.   (View)

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Voltage_to_frequency_convener_for_single_supply_operation

Published:2009/7/20 3:45:00 Author:Jessie

Voltage-to-frequency convener for single supply operation. Full scale output is 10 kHz. The chip used is a Datel VFQ-1 14-pin DIP (courtesy Datel Systems, Inc.).   (View)

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Frequency_to_voltage_converter_for_a_0_to_100_kHz_input

Published:2009/7/20 3:44:00 Author:Jessie

Frequency-to-voltage converter for a 0 to 100 kHz input. Chip used is a Datel VFQ-1 (courtesy Datel Systems, Inc.).   (View)

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FET_PROBE

Published:2009/7/9 20:47:00 Author:May

This FET probe has an input impedance of 10 MΩ shunted by 8 pF. Eliminating the protective diodes reduces this impedance to about 4 pF. The frequency reiponse of the probe extends from dc to 20 MHz (-1 dB), although higher frequency operation is possible through optimized construction and use of a UHF-type transistor. Zero dc offset at the output is achieved by selecting a combination of a 2N5246 and source resistor that yields a gate-source bias equal to the Pjyg of the 2N3704 at approximately 0 V. At medium frequencies, the probe can be used unterminated for near-unity gain; for optimum impedance converter probe high-frequency response, the cable must be terminated into 50 Ω. The voltage gain, when properly terminated, is precisely 0.5 X.   (View)

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IR_HEAT_CONTROLLED_KITCHEN_FAN

Published:2009/7/9 20:45:00 Author:May

Q1 senses IR from heat sources, causes U1 to switch, activates optocopuler U1, and triggers TR1.This controls a fan. The Triac is from Radio Shack, or else a 200-V, 6-A unit (C106B) can be used.   (View)

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BATTERY_POWERED_GROUND_NOISE_PROBE

Published:2009/7/9 20:44:00 Author:May

Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope's three-pronged power plug. You can avoid this problem by using the ground-noise tester shown. Powered by two 9-V batteries, the circuit dissipates power only while push-to-test switch S1 is depressed. Noise pulses that reach IC2A's switching threshold of about 1.5 to 1.8 V create a logic transition that triggers the monostable multivibrator IC3, which stretches the pulse to produce a visible blink from LED D1.You set the noise reference level by adjusting threshold-adjust potentiometer R1, which lets the circuit respond to minimum pulse amplitudes ranging from about 0 to 1 V. For convenience, you can use a one-turn potentiometer for R1 and calibrate the dial by applying an adjustable dc voltage, monitored by an accurate voltmeter.   (View)

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INTERNAL_RESISTANCE_BATTERY_TESTER

Published:2009/7/9 20:42:00 Author:May

A designer often needs to know the value of the internal resistance of a battery. Quite a few testers give a relative indication of the value, but this is seldom in ohms. The present tester can, in principle, provide that information. The basic idea behind it is to load the battery with a varying current, so as to cause an alternatingvoltage drop across the internal resistance that can be measured at the battery terminals. Provided that current variations are regular and constant, the voltage drop is directly proportional to the internal resistance. Choose the variation of the current carefully to read the value of the internal resistance directly on the scale of an ac voltmeter. The load current is varied with the aid of a current source, T1 in the diagram, which is switched on and off by square-wave generator IC1. The chosen switching frequency of 50 Hz ensures that the ac component at the battery terminals can be measured by a standard ac voltmeter (universal meter). The battery is loaded constantly by R8, which has a value of 1.5Ω for 1.5-V batteries, shunted by the ac voltmeter. The indicated voltage times 10 is the value of the internal resistance of the battery. When the battery under test is flat or if the supply battery is flat, no current flows and the meter will read zero. It would then appear as if the battery under test is an ideal type-without internal resistance. A flat supply battery is indicated if Dl does not light. You can ascertain that the battery under test is flat by measuring the direct voltage across its terminals. The load must be left connected, of course, oth-erwise the emf is measured and this may well be 1.5 V-even if the battery is flat. The tester is calibrated with the aid of the auxiliary circuit (shown at the extreme right in the circuit diagram). The 1.5-V supply and electrolytic capacitor form a virtually ideal voltage source, of which the 3.9-Ω resistor forms the internal resistance. With this source connected across the output terminals of the tester, a suitable value should be ascertained for R7. That value is found when the ac voltmeter shows 0.39 V. Notice that this procedure is not the same for all measuring instruments: the alternate use of the digital and a moving coil meter, for instance, is not feasible. The tester is intended for 1.5-V batteries. The load current is fairly high: about 100 mA through R8 and around 170 mA through T1. For 9-V batteries that current is too high: the current should then be reduced by taking greater values for R6 through R8.   (View)

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4_220_V_TEST_PROBE

Published:2009/7/9 20:42:00 Author:May

Using inexpensive components, you can fit a simple probe circuit into a pencil-sized enclosure. When both LEDs are on, the probe indicates the presence of an ac voltage; either LED alone indicates the presence and polarity of a dc voltage. The diode-bridge arrangement allows one-way current source R1, R2, Q1, and Q2 to light either LED (or both) when the probe is activated by a test voltage. Diodes, provide the necessary peak-inverse voltage rating; R3 and C1 provide a spike-suppression network to protect the current-source transistors.   (View)

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CMOS_UNIVERSAL_LOGIC_PROBE

Published:2009/7/9 20:40:00 Author:May

Only the CD4009AE hex buffer, two resistors, and two LEDs are required for a logic probe. CMOS logic probe features 1012Ω input impedance and covers 3 to 15 V range. While LEDs are visible at all voltages, a 1-KΩ pot in place of R2 will allow the user to increase brightness at lower voltages.   (View)

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RF_PROBE

Published:2009/7/9 20:38:00 Author:May

This rt probe is coupled with a fiber-optic cable to the test equipment. It utilizes inexpensive components to improve probe performance at UHF frequencies. The receiving antenna in this probe feeds an envelope-detector diode. After amplification by the LF356 op amp, the low-frequency output modulates the LED, which in turn feeds the optical fiber. The design facilitates the use of a single battery for the op amp, with voltage splitting by means of the 1-KΩ potentiometer, and miniature 47-μF tantalum capacitors to provide decoupling. The gain control is easily adjusted to give the best dynamic range for a specific LED.   (View)

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INERARED_

Published:2009/7/9 20:37:00 Author:May

This circuit uses an Amperex pyroelectric IR sensor, an LM324 op amp (conftgured as a high-gain amplifier in the 0.3-to 5-Hz range), and a win-dow detector. The output will go high on any motion, which will change the infrared signature seen by the sensor.   (View)

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LOW_INPUT_CAPACITANCE_BUFFER

Published:2009/7/9 20:37:00 Author:May

Q1 and Q2 constitute a simple, high-speed FET input buffer. Q1 functions as a source follower, with the Q2 current-source load setting the drain-source channel current. The LT1010 buffer provides output drive capability for cables or whatever load is required. The LTC1052 stabilizes the circuit by comparing the filtered circuit output to a similarly filtered version of the input signal. The amplified difference between these signals is used to set Q2's bias, and hence Q1's channel current. This forces Q1's VGS to whatever voltage is required to match the circuit's input and output potentials. The diode in Q1's source line ensures that the gate never forward biases and the 2000-pF capacitor at A1 provides stable loop compensation. The rc network in A1's output prevents it from seeing high-speed edges coupled through Q2's collector-base junction. A2's output is also fed back to the shield around Q1's gate lead, bootstrapping the circuit's effective input capacitance to less than 1 pF.   (View)

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07_watt_audio_power_amplifier_using_an_ECG1036

Published:2009/7/20 5:03:00 Author:Jessie

0.7-watt audio power amplifier using an ECG1036. Typical voltage gain at 1 kHz is 50 dB. Input impedance is 20K. Frequency response is from 50 hertz to 100 kilohertz (courtesy GTE Sylvania).   (View)

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The medical electric aspirator waterproof controller (1)

Published:2011/7/21 19:55:00 Author:qqtang | Keyword: aspirator, waterproof controller

The working principle of the circuit The medical electric aspirator waterproof controller circuit consists of the power supply circuit, liquid level detection control circuit and acousto-optical alarm circuit, see as figure 9-46. The power supply circuit consists of the transformer T, power supply indicator HL1, rectifier diode VDl-VD4 and filter capacitor C1. The liquid level controller circuit consists of the detection poles a and b(inserted in the bottleneck of the liquid bottle), transistors V1 and V2, diode VD5, relays of K1 and K2 and the step switch S.   (View)

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42_watt_AF_power_amplifier_using_an_ECG1153_10_pin_SIP

Published:2009/7/20 5:04:00 Author:Jessie

4.2-watt AF power amplifier using an ECG1153 10-pin SIP. Recommended supply voltage is 13.2 volts. The 4.2-watt rating is with a 4-ohm load. Typical voltage gain is 42 dB, Input resistance is 70K (courtesy GTE Sylvania Incorporated).   (View)

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2_watts_per_channel_dual_AF_power_amplifiers_using_an_ECG1154_14_pin_DIP

Published:2009/7/20 5:05:00 Author:Jessie

2-watts-per-channel dual AF power amplifiers using an ECG1154 14-pin DIP. Recommended supply voltage is 14 volts. Input resistance is 80K. This circuit is intended for low-cost stereos. Frequency response is from 60 hertz to 30 kilohertz (courtesy GTE Sylvania Incorporated).   (View)

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Eight_10_bit_A_D_converters_multiplexed_with_the_6800_microprocessor_through_a_single_PIA

Published:2009/7/20 4:56:00 Author:Jessie

Eight 10-bit A/D converters multiplexed with the 6800 microprocessor through a single PIA(courtesy Analog Devices, Inc.).   (View)

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