RF indicator

123

01:26:29

You see this used by most people to check if the mains are still on, but I think it's a cool little circuit. Using two transistors to amplify the signal and the third is to turn on the led, speaker, buzzer, or what have you.

published 11 years ago

thebugger

11 years ago

RF stands for radio frequency and it applies for UHF/VHF. That means at least MHz. 60Hz lies at the low end of the AF (Audio Frequency) spectrum. An RF probe is different. It uses a diode to rectify the high frequency signal and a cap to filter it and feed it into a multimeter or an LED or even a sequence of LED's to measure the RF power level.

Voltransistor

11 years ago

You need a capacitor from the input frequency to the first transistor. The capacitor indicates only "change" in direction(ac) and you would need a small value capacitor, for Radio Frequency(KHz-MHz), high frequencies. It would only indicate Radio Frequency, when the capacitance is low for the input.

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