Free electronic circuit design and schematic diagram
A meter amplifier can be designed using LM10 integrated circuit (IC). The accuracy of full-scale sensitivity is good for over 15°C to 155°C at 10mV and 100nA. Here is the schematic diagram of the circuit: R5 is used to correct the offset voltage error, while R4 is used to balance the bias current. The zero calibration uses the reference voltage […]
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This circuit gives a changing-color LED display, where a LED will emit a dynamic shifting color, from red to green smoothly through yellow. The circuit uses NE556 dual timer, equal to two 555 IC but in only one package. The oscillators is set at different frequencies. The high frequency (upper part) is used to construct a PWM signal, and the […]
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It will be effective to use simple half wave motor speed control with small universal ac/dc motors. Two amps RMS is the maximum current capability. The control gives excellent torque characteristics to the motor because speed dependent feedback is provided, even at low rotation speeds. By closing switch S1, thus bypassing the SCR, we can achieve normal operation at maximum […]
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Using LM134 and LM10 integrated circuits, we can build a thermometer which has -55 to 150°C sensing range. The ideal meter for this circuit is a 0-200uA digital ampere meter, which can show both positive and negative polarity. This will make the circuit suitable for indicating temperatures below 0°C. LM134 is basically a current source with very accurate and consistent […]
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A battery level indicator circuit is depicted in the schematic diagram below. This circuit is designed for 9V battery operation, as this circuit will start dimming below 7V and will be completely turned off at 6V. If you want the LED indicator not to dimming but just abruptly turns off at below 6V, then you can remove R3, and change […]
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Using LM10 amplifier and voltage reference, a light intensity meter featured with five decades dynamic range (which is suitable for photographic application) can be built. Please note that the linear to log conversion is not temperature compensated, and can make 40% error (a half stop in photography) at the worst point of conversion slope at ±18°C temperature drift. It should […]
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National LM378 amplifier is used as a basis for economical proportional motor speed controller. This integrated circuit is able to deliver 700 mA continuous current for such DC motor applications such as antenna rotors or motor controlled valves. The basic of proportional control is as simple as amplifying the error signal to produce an action in such direction that minimize […]
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