Circuit Diagram

Low_power_step_up_converters

Published:2009/7/24 8:46:00 Author:Jessie

The table of Fig. 4-52B lists the measured efficiency of circuits using the indicated coils. Efficiencies can be improved slightly by placing a Schottky diode (such as the 1N5817) in parallel with the intemal diode, from pin 4 to 5. The increase in efficiency is most noticeable for the 5-V output circuits.   (View)

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_5V_from_a_3_V_battery_with_no_inductors

Published:2009/7/24 8:44:00 Author:Jessie

This inductorless dc/dc converter generates a regulated +5 V at up to 100 mA from a single lithium cell. When powered by a DL123A (smaller than an AA cell), the circuit provides 40 mA of load current for 12 hours or more. The MAX660 in a doubler configuration steps up the battery voltage to +6 V, which is then regulated down to + 5 V by the MAX667. The surface-mount version of this circuit occupies only 1/2 square inches of PC-board space, because the circuit uses capacitors instead of inductors. The circuit capitalizes on the low dropout voltage of the MAX667 (typically less than 100 mV at 150 mA) and the 100-mA load capability and 95% efficiency of the MAX660.   (View)

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DATA_SEPARATOR_FOR_FLOPPY_DISKS

Published:2009/6/30 23:42:00 Author:May

The data separator is intended for use with 8 flexible diskettes with IBM 3870 soft sectored format. The circuit delivers data and clock (B) and clock pulses (D). These two signals must be in such a sequence that the negative edge of the clock pulse is at the middle of a data cell.Unseparated data (A) from the floppy unit is shaped with one shot N1. Trimmer P1 should be adjusted so that pulses (B) are 1 μs wide. This signal synchronizes PLL N2 with a free running frequency adjusted to 500 kHz. The output of the PLL is 90°out of phase with its input. D-type flip-flop N3 is connected as a divider by two and changes state at each positive edge of (C). N4, connected as a shift register, looks for four consecutive missing pulses. When this happens, the circuit is resynchronized with (E) so that the negative edge of (D) is in the middle of a data cell.   (View)

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Charge_pump_with_shutdown

Published:2009/7/24 8:43:00 Author:Jessie

In this circuit, a MAX660 charge pump is used as a voltage inverter, creating a negative voltage of approximately equal magnitude to the input voltage. Although the MAX660 has no feedback mechanism, and so is unregulated, the output is a stiff, accurate supply when operated from a regulated input. An output current of 100 mA results in a typical voltage loss of 0.65 V (the drop at 10 mA is less than 100 mV). The FC input selects a 10- or 45-kHz oscillator frequency. Notice that this circuit provides an optional shutdown that disables the internal oscillator, and reduces the supply current to less than 1μA.   (View)

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Battery_management_circuit_with_ultra_low_standby

Published:2009/7/24 8:41:00 Author:Jessie

This circuit controls four loads via low on-resistance N-channel MOSFETs. If all four switches are programmed off, the power supply input to the MAX620 is disconnected, and the standby supply drain is reduced to 2μA.   (View)

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STABILIZING_A_LASER_DISCHARGE_CURRENT

Published:2009/6/30 23:39:00 Author:May

The circuit uses a free-running push-pull dc to dc high voltage converter to get the necessary voltage for the laser plasma tube supply. The supply voltage VC of this converter, is adjusted by a switch-mode power supply in order to keep the load current constant, at set value. The linear opto-electronic isolator U2, connected in series with the laser plasma tube, gives a voltage VF proportional to the discharge current ID across R18, having the correct polarity to drive directly the inverting input of U1, D7, R15 protects the optoisolator diode against damage produced by the high voltage ignition pulse.Due to the high operating frequency of the high voltage converter (25 kHz) the ripple of the laser output power is less than 2.10-4. The stability of ID is better than 10-2, for variations of supply voltage VS is the range of ±10%, and depends on the optoisolator sensitivity.   (View)

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6_DIGIT_LED_WITH_SLEW_BUTTONS

Published:2009/6/30 23:39:00 Author:May

National MM5313 PM05 digital clock IC drives display which includes four discrete LEDs mounted on readout panel to form colons between hours, minutes, and seconds. AC supply provides 14 VDC for IC and 7 VDC for displays. Hold push-button SWt stops count to give precise seconds setting. Slow-slew button SW2 advances time at 1 min/s for precise setting, and fast-slew but-ton SW3 advances time 1 h/s. Digit drivers Q1-Q12 are Darlington-connected pairs of PNPtran-sistors. Segment drivers Q13-Q19 are single PNP transistors.-M. S. Robbins, Electronic Clocks and Watches, Howard W. Sams, Indi-anapolis, IN, 1975, p 103 and 113.   (View)

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Regulated_power_distribution_system

Published:2009/7/24 8:38:00 Author:Jessie

In this circuit, the LM10 linear regulator provides a maximum dropout voltage (at 25℃) of less than 90 mV at 5 A when used with a low-resistance MOSFET (such as an SMP60N06-18). The load switches are driven by the high-side voltage, which is regulated at + 11V above the supply voltage, via the four on-board latched-level translators.   (View)

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Full_function_portable_power

Published:2009/7/24 8:37:00 Author:Jessie

This circuit provides a variety of outputs for battery-operated micro-processor systems. All of the outputs are under microprocessor control. A 5-cell NiCd battery is used for the main power source, with a 3-V lithium back-up battery One of the outputs is negative (and is controlled by a 5-bit on-board D/A converter) for LCD contrast adjustment.   (View)

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Z80_CLOCK

Published:2009/6/30 23:39:00 Author:May

The circuit will operate reliably from below 1 MHz to above 400 MHz. With Vcc=5V the output of the second inverter essentially attains a full swing from O V to 5 V. Such large logic output levels and broad frequency range capabilities make this oscillator quite suitable for driving MOS components such as CPU, controller chip, peripheral devices, as well as other TTL products. A damping resistor in series between the clock output of the oscillator and the input of the device being driven will remove the undesirable undershoot and ringing caused by the high speed CMOS part.   (View)

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Battery_input_buck_boost_regulator

Published:2009/7/24 8:36:00 Author:Jessie

This circuit converts an input voltage that can range from above （6 V) and below （4 V） the desired output voltage (5 V). Normally, such a circuit must provide both step-up and step-down actions. However, if the input ground can be floated, as is often the case with a battery, an inverter can be used instead of a transformer or a complicated and lossy step-up/down circuit by fixing the most-negative output voltage at ground.   (View)

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Step_up__5_V_output_from_two_AA_cells

Published:2009/7/24 8:35:00 Author:Jessie

In this circuit, a MAX655 provides a +5-V 60-mA output from two AA battery cells. The circuit also provides a +12-V 500-μA output. Notice that the low-battery detector (LBO) is used as a level translator for optional high-side switching. Standby current is 80μA (with the +5-V output still alive and regulating) and efficiency is 82%.   (View)

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TRANSISTORIZED_FLASHERS

Published:2009/6/30 23:38:00 Author:May

Transistors Q1 and Q2 are connected as a free running multivibrator. The output, at the emitter of Q2, drives the base of the common emitter amplifier Q3, which controls the lamp. This circuit configuration permits the flash duration, the interval between flashes, and the lamp type to be varied independently. Flash duration is proportional to the prod-uct of R2C2 while the off interval is proportional to the product of R3C1. Consequently, when the flash timing must be accurately maintained, these component tolerances will have to be held to similar limits.All three circuits described are designed for barricade warning flasher lights such as used in highway construction. They differ only in flash duration which normally is 15%, 25%; or 50% of the flash rate. Performance has been checked at ambient temperatures of -40'F, 77'F, and 212°F. A GE 5 volt, 90 milliampere type No. 1850 lamp is used.   (View)

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HIGH_DRIVE_OSCILLATOR_FLSHER

Published:2009/6/30 23:34:00 Author:May

The driver in the package is connected as a Schmitt trigger oscillator (A) where R1 and R2 are used to generate hysteresis. R3 and C are the inverting feedback timing elements and R4 is the pull-down load for the first driver. Because of its current capability, the circuit can be used to drive an array of LEDs or lamps. If resistor R4 is replaced by an LED (plus a current limiting resistor), the circuit becomes a double flasher with the 2 LEDs flashing out of phase (B).   (View)

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LASER_LIGHT_DETECTOR

Published:2009/6/30 23:30:00 Author:May

The laser light detector utilizes a sensitive photo transistor (Q5) placed at the focal point of a lens (LE2). The output of Q5 is fed to a sensitive amplifier consisting of array (A1) and is biased via the voltage divider consisting of R14 and R1. The base is not used.Q5 is capacitively coupled to a Darlington pair for impedance transforming and is further fed to a capacitively coupled cascaded pair of common-emitter amplifiers for further signal amplification. Sensitivity control (R7) controls base drive to the final transistor of the array and hence controls overall system sensitivity. Output of the amplifier array is capacitively coupled to a one-shot consisting of Q1 and 6|2 in turn integrating the output pulses of Q2 onto capacitor C8 through Dl. This dc level now drives relay drivers 6)3 and 6)4 activating K1 along with energizing indicator D3, consequently controlling the desired external circuitry. The contacts of K1 are in series with low ohm resistor R13 to prevent failure when switching capacitive loads. J2 allows listening to the intercepted light beam via headsets. This is especially useful when working with pulsed light sources such as GaAs lasers or any other varying periodic light source.   (View)

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Cold_cathode_fluorescent_lamp_CCFL_power_supply

Published:2009/7/24 8:24:00 Author:Jessie

CCFLs are often used to backlight the LCD displays of portable computers． Such lamps require a high-voltage sine-wave drive. This circuit provides such drive，and permits lamp intensity to be varied continuously and smoothly from zero to full intensity. Notice that a Tektronix probe type P-6009（acceptable）or types P6013A and P6015（preferred）probes must be used to read the L1 output，The vast majority of oscilloscope probes will break down if used for this measurement，unless the probes are rated for wideband high voltage   (View)

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Function_generator_with_wide_tuning_range

Published:2009/7/24 8:23:00 Author:Jessie

The adjustment range of this generator is in excess of 1,000,000/1, using a single frequency-adjust potentiometer. C1, C2, and C3 shape the triangular signal between 500 kHz and 1 MHz. C4, C5, and the 50-kΩ trimmer are adjusted to maintain essentially constant (±10%) amplitude up to 1 MHz. Harris Semiconductor, Linear and Telecom ICs, 1991, p. 3-224.   (View)

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LOW_FREQUENCY_OSCILLATOR_FLASHER

Published:2009/6/30 23:29:00 Author:May

Electrolytic capacitors are unnecessary to generate a 1 cps frequency. As an scs triggers on, the 0.2 μF commutating capacitor turns off the other one and charges its gate capacitor to a negative potential. The gate capacitor charges towards 24 volts through 20 M retriggering its scs. Battery power is delivered to the load with 88% efftciency.The 20 M resistors can be varied to change prf or duty fact   (View)

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Regulators_with_ultra_low_dropout

Published:2009/7/24 8:22:00 Author:Jessie

Battery life is significantly affected by the dropout performance of linear regulators. These circuits offer lower dropout voltage than any monolithic regulator (below 50 mV at 1 A, increasing to only 450 mA at 5 A). Line and load regulation are within 5 mV, and initial output accuracy is inside 1%. The circuits are fully short-circuit protected, and have no-load quiescent current of 600μA. Figure 4-37B shows a simple way to add shutdown to the regulator of Fig. 4-37A.A CMOS inverter or gate biases Q2 to control LT1123 bias. When Q2 is driven, the loop functions normally. With Q2 unbiased, the circuit goes into shutdown and pulls no current.   (View)

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Simple_voltage_programmable_current_source

Published:2009/7/24 8:21:00 Author:Jessie

This circuit produces output current in strict accordance with the sign and magnitude of the control voltage, with no trimming required. Circuit accuracy and stability depend almost entirely on resistor R. Figure 4-36B shows dynamic response for a full-scale input step. Trace A is the voltage-control input and trace B shows the output current.   (View)

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