Inside Circuits

The input signal is applied through R3 to the inverting input of the summing amplifier and the output is taken from the first integrator. The summing amplifier will maintain equal voltage at the inverting and non-inverting inputs. Defining 1/R1C1 as 1 and 1/R2C2 as u>2> th^ is now a convenient form to look at the center-frequency 0 and filter Q. ..

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Because of its high amplification factor and built-in power-output stage, an integrated power operational amplifier makes a convenient driver for ac motors. One op amp can be configured as an oscillator to generate the required ac signal. The power-output stage, of course, supplies the high-current drive to the motor. ..

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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..

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This circuit relies on extremely high input impedance for effective operation. The HA-5180 with its JFET input stage, performs well as a preamplifier. The standard three amplifier configuration is used with very close matching of the resistor ratios R5/R4 and (R7 + R8)/R6, to insure high common-mode rejection (CMR). The gain is controlled through R3 and is equal to 2RI/R3. Additional gain can be had by increasing the ratios R5!R4 and (R7 + R8)!R6. ..

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The detector circuit compares the output voltage of two separate voltage dividers with a fixed reference voltage. ..

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The optocoupler (as shown) provides load sensing for a 3-terminal regulator, such as the LM317 series. Rl sets a cu..

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An IR photodiode, which senses IR skin reflectivity as a result of increased blood volume during the periods that the heart forcibly contracts, is used to pick up a signal that is correlated with the heartbeat...

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This circuit generates noise pulses that are suitable for test purposes, etc. A zener diode is used as a noise source. IC1 is a relaxation oscillator. PI determines noise bandwidth, and P2 and P3 the noise amplification...

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A GC Electronics P/N J4-815 transducer is used to receive 40-kHz acoustic remote-control signals...

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The MAX712 and MAX713 are nickel cadmium (Ni-Cd) battery fast charge controllers which will fast charge batteries from a DC source at least 1V higher than the maximum battery voltage. 1 to 16 series cells can be charged at rates up to 4C. A voltage-slope detecting analogue-to-digital converter, timer, and temperature window comparator determine charge completion. The MAX712 or 713 are powered by the DC source via an on-clip +5V shunt regulator, and draw a maximum of 5uA.....

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The cyclic converter consists of a chain of identical stages, each of which detects the polarity of the input. Step V REF then subtracted from the double entry and the rest if the polarity is correct. The signal is full wave rectified and the rest of V IN - V REF is doubled. ..

A light dimmer, a 1 µf capacitor and a 12 V car ignition coil form the simple line powered HV generator. The current in the dimmer is shown in Fig. B. At times tp t2, set by the dimmer switch, the inner triac of the dimmer switches on, and a very high and very fast current pulse charges the capacitor through the primary of the induction coil. Then at a rate of 120 times per second for a 60 Hz line, a very high voltage pulse appears at the secondary of the coil...

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This circuit operates at or near series resonance..

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With a constant current excitation, the voltage dropped across an inductance in-(in creases with frequency. Thus, an active device whose output increases with frequency can be characterized as an inductance. The circuit yields such a response with the effective inductance being equal to: L = R1R2C. The Q of this inductance depends upon Rl being equal to R2..

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To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves this by using a diode to lower the effective supply voltage on the 8038..

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This detector is useful in sine wave squaring circuits and A/D converters. The positive input may either be grounded or con-output nected a nulling voltage which cancels input offsets and enables accuracy to within microvolts of ground..

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This circuit can be used to operate a VCR or CD player from another room. It"s really an infrared signal repeater. The s..

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This circuit has a 741 audio amplifier, which is fed by a microphone (use an amplified type), an FM..

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Integrated circuit Ul is connected as a low-frequency asymmetrical oscillator. Its output is inverted by Ql and fed to the reset te..

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LEDs indicate at a glance what the status of the circuit is at any given moment. Once the reset switch, SI, makes contact,..

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