DC Motor speed regulator
This speed regulator uses a single IC LM1014 to control the speed of a DC motor. It senses the increase in the motor-current when the rotation of the motor slows down due to a load.
The IC then increases the motor voltage so that the original speed is recovered. P1 potentiometer varies the speed of the motor.
DC motor speed regulator circuit schematic
Field strength meter
A sensitive and reliable field strength meter is an invaluable instrument in amateur radio and in radio controlled model area. A field strength meter is used to align an antenna to get the best possible gain, to determine the transmitting range of radio controllers …
Designing the field strength meter to be sensitive it is a requirement because there must be as many wavelengths as possible between the meter and the transmitter, the measurement can be done without using a stronger carrier signal and most of the radio controllers are of low power type.
Considering these factors, a dual MOSFET is used as an RF amplifier in this circuit. The amplification can be adjusted by P1 and with S1 switch we can select three
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Simple cable tv amplifier
This cable tv amplifier is a rf-amplifier designed to be quickly installed between two coaxial cables. Both input and output impedances are compatible with 75 Ω cables.
The main amplifier si T1 transistor, T2 is working as an emitter follower. The feedback bias is determined by R3 and R4. The total gain of this tv cable amplifier is 22dB.
Because of the high frequency limit of transistors (<= 2GHz) the tv amplifier works well up to 150 MHz. It must be housed in a metal case and the coaxial cables must de 75 Ω type. The total current consumption of this tv cable amplifier circuit is around 20mA.
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