"Howard K0ACF" napisał w wiadomości
...
"Szczepan Bialek" wrote in message
.. .
"The wire antennas used with crystal receivers are monopole antennas
which develop their output voltage with respect to ground. They require a
return circuit connected to ground (earth) so that the current from the
antenna, after passing through the receiver, can flow into the ground."
I had a crystal radio & the antenna was a piece of wire hanging out of it
& the radio was built in a wooden box & I could listen to it on the second
floor of a wooden building & sitting on a wooden chair. no connection to
the ground (earth) as you say is required & the station I listened to was
a daytime station located about 50 miles away...How did it work & no
connection to the ground (earth) as you say is required & no battery power
& the crystal had a cat wisker for tuning...
Ian wrote:
"Normally there is a tuned circuit at the input, which consists of a
coil and capacitor in parallel. The DC flows through the coil.
At the output there either is a high-impedance magnetic headphone,
which conducts DC through its coil, or a crystal headphone with a
resistor in parallel for the DC path."
Next the DC flows into "ground":
"The use of the term ground (or earth) is so common in electrical and
electronics applications that circuits in portable electronic devices such
as cell phones and media players as well as circuits in vehicles such as
ships, aircraft, and spacecraft may be spoken of as having a "ground"
connection without any actual connection to the Earth. This is usually a
large conductor attached to one side of the power supply (such as the
"ground plane" on a printed circuit board) which serves as the common return
path for current from many different components in the circuit." From:
http://en.wikipedia.org/wiki/Ground_(electricity)
Each charged body (conductor and insulator) losts the charge (leakage) with
time.
Add the additional real ground and tell us the results.
S*