Free electronic circuit design and schematic diagram
The large issue today that caused by more electronic equipment enters the home and the office is noise of fan. to reduce fan noise, a variable speed fan is used because it permits quieter and slower, fan speed when temperature conditions allow. To build a variable speed fan we can use digital control or high-speed/low-speed switches. Digitally controlled fans perform […]
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This is a circuit that transmits temperature data over an IR link and it allows the isolation of temperature sensor. It is a good solution of obtaining temperature readings from points at potentials a few tens of volts from ground by linking a temperature probe only by an IR connection to the readout point. This circuit consist of a temperature […]
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We usually use a fan to manage the temperature, but it produces audible noise at full speed. To reduce this noise we can use this circuit. The first circuit reduces the noise by controlling the cooling-fan speed as a function of temperature. It uses an IC that combines temperature sensing with a PWM output. When the temperature of the processor […]
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There are some digital and analog that can be used for compensating a PT100 RTD nonlinearity. We can implemented the digital linearization by implementing the previous generic equation or by a lookup table. By implementing the previous generic equation we can calculate temperature values directly, based on the actual measured RTD resistance. A lookup table allows an application to convert […]
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In some temperature-sensing applications there are some problems caused by the placement of sensors on location where the potential is very different from that of the data-acquisition-system common. So the operating temperature sensor must be isolated from its data-acquisition system galvanically. And the power’s source for the sensor was isolated. This circuit is designed to solve that problem. It provides […]
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To know someone is lying or not we can use lie detector. This is a simple lie detector that can be made in minutes. It works to detect the someone who telling lie but it is not as sophisticated as the ones the professionals use. Here is the schematic diagram of this circuit: The skin resistance will go down when […]
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The transmitters that either working in FM or in AM is familiar. This is transmitters circuit that can transmit both FM and AM signal simultaneously at two different frequencies FM in 100Mhz and Am in 20 MHz. Here is the circuit: To transmit the FM signal, this circuit uses the 5th harmonics of the fundamental 20Mhz. So the range of […]
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