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.
of the RF Sniffer near Antenna of WiFi
of the RF Sniffer near Antenna of Cell phone