Thermoelectric Heat Pump for Laser Diodes Stabilization

Usually, semiconductor laser diodes are operated from current drives. Unfortunately, The output power is strongly dependent on the device temperature – a rise of 15° causes a fall in optical power of (typically) 17% for a given current. Using a feedback loop and monitor the output beam intensity using photodiode is one method to stabilizing the operating condition. Not an […]

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LM3404 Constant Ripple LED Driver

To take an input voltage of 24VDC ±10% and drive 1A through as many LEDs in series as the maximum output will allow, the circuit shown in the schematic diagram below uses the ONO-based constant ripple concept. The average current controls the luminous flux and dominant wavelength (or color temperature for white LEDs). Because the constant-ripple LED driver fixes the […]

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TL084 Audio Compressor (AGC)

Compressor or AGC (automatic gain control) is used to manipulate the average amplitide of audio signal, to produce relatively constant volume of signal from high dynamic signal source. The 2N3819 JFET (which is used as a voltage controlled resistor) is the key component. Control voltage which is derived by full-wave rectification followed by a peak detector is provided by the […]

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Automotive Voltage Regulator with Keep Alive Control

The LM9070 is a 5V, 3% accurate voltage regulator which have 250mA low-dropout. The regulator has an active low delayed reset output flag feature. This feature can be used to reset microprocessor system on turn-ON and in the event that the regulator output falls out of regulation for any season. Before the reset output can return high, an external capacitor […]

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DC Motor Control System Block Diagram

A schematic arrangement for a two quadrant controller is shown on figure below. This figure show us the outer speed control loop and the inner current control loop. The tachogenerator derive the speed feedback signal, although alternatively an approximation to the motor speed can be derived by feeding back a signal proportional to the motor voltage, (AVF). For servo applications, […]

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SCR And Triac Triggering Circuit With A Positive Power Supply

The control-circuit output current has to be amplified when the gate current required to trigger the device is higher than the control-circuit output current capability. For example, A lot of MCUs feature output pins with a current capability around 30 mA today. With IGT, they can switch Triacs safely up to 15 to 20 mA. Below are two solution if […]

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Class G Power Amplifier with LM48824

Class G audio power amplifier uses two (or more) separate voltage supplies with different levels, take the benefit of AB class amplifier when operated its  almost full signal swing.  With two different level of supply voltage, the efficiency is significantly improved while maintaining the best accuracy (low distortion) of linear amplifier. The LM48824 is a Class G, ground-referenced stereo headphone […]

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