Free electronic circuit design and schematic diagram
A laser diode driver can be implemented using voltage-controlled current source. This simple linear laser diode driver gives cleaner drive current than a switched (PWM) drivers. Here is the schematic diagram of the circuit: A Howland current pump with a current booster is used as the basic of this laser diode driver. Q1 is used as the current booster on […]
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All of the necessary circuitry to optimally control the charge and hold cycle for sealed lead acid battery can be implemented using UC2906 series of battery charger controllers. These integrated circuits monitor and control both the output voltage and current of the charger through three separate charge states; a high current bulk-charge state, a controlled over-charge, and a precision float-charge, […]
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Stepper motor gives a simple, low cost, and accurate position control. Stepper motor can be driven by circuit mounted close to the motor, and controlled by a remote control circuit through long cable. The interesting thing of this circuit is that the power for both motor and the driver circuit is carried over two wires, the same wires that carry […]
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Closed Loop Motor Control Closed loop (servo) control is used to make a constant speed motor control. Constant speed means that the speed of the motor will be kept constant although the load is change, or even when the electric supply voltage is also changed. The circuit maintain the speed at a constant value by sensing the actual speed using […]
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Bubba oscillator is another example of phase shift oscillator. The Bubba oscillator takes the advantage of quad op-amp package to get 45 degree phase shift for each section. The result is excellent d(phase)/d(t) to get very low frequency drift. Here is the schematic diagram of the circuit: Each RC section give 45 degree phase shift. A low impedance quadrature output […]
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Thermoelectric cooler (TEC) or Peltier cooler is becoming popular because of its robustness and maintenance free characteristic. Here is one example of a linear thermoelectric cooler (TEC) driver circuit. This driver is capable of delivering ±2A into a TEC. This circuit operates on a single +5V supply and drives the TEC in the most preferred “constant-current” mode. Here is the […]
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This SMPS AC-DC converter gives good efficiency. Test data shows efficiency of 83.2% at 115 Vac input and 6A output current, and 85.4% at 230 Vac input and 6A output current. Moreover, the input voltage range is universal, accommodating 92 to 276 Vac variation with only 24 mV change in the output voltage. Here is the schematic diagram of the […]
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