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ANTENTOP- 01- 2018 # 022

RF Sniffer



FSM with 1SS315 diode could successfully catch cell phone-needle of the meter flapping at the edge of the meter, router and notebook WiFi - almost 100 percent of the scale, mouse and keyboard docking station- near 20 percent of the scale, microwave oven- near 20 percent of the scale. It was just interesting to meter and compare. The RF Sniffer allows find where is installed an antenna in those devices. When I have played enough with the RF catcher I decided make a small brother of the RF Sniffer- simple Sniffer with LED instead of the meter.



Simple RF Sniffer

Figure 3 shows simple RF Sniffer with LED as the RF indicator. It is a very simple circuit. It consists of inductor (or RF receiver- antenna), RF diode and LED. The LED is very important part for the simple RF Sniffer. This LED should have as low as possible forward voltage and current for lighting. Before going to E- Bay to find a suitable one I went to garage to check old toy box belonged to my son. The modern toys are contained lots electronics parts so I time to time use the old toys to harvest some parts needed to me. Again I was lucky because I found several low voltage (1.7-V forward) low current (2.5- mA) LEDs. Simple calculation shows that at 2 V RF on the inductor the LED should be glow (0.25- V on detector diode plus 1.7-V on LED).



Figure 3 Simple RF Sniffer with LED as RF Indicator


The first version of the LED RF Sniffer was made to catch RF from cell phone. L1 is a loop of wire in 12- cm length. Diameter of the wire is 1 mm. When the Sniffer was placed at antenna location on the cell phone the LED glows up very bright according to transmitting. However, I could not found any useful application for the device...


So I decided to do LED RF Sniffer for something useful. For me it was usual HF FSM and RF current meter.




Breadboard of the RF Sniffer near Antenna of WiFi Router




Breadboard of the RF Sniffer near Antenna of Cell phone



LED RF Sniffer

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Last Updated:

January 3, 2020 21:22