hiya
i found this and was woundering how the capacitor is used as the
detector, would there be an ajustable way of achieving this??
http://www.web-ee.com/Schematics/Radar Detector/rad_det.htm
cheers
greg
Yes, and yes. Actually, tha cap's leads are the antenna - sort of
a loaded half-folded-dipole, ... nah! it's just a quarter-wave whip.
The cap value is irrelevant. The 1458 does the detecting with the
e-b junctions of the input transistors. And it's clearly adjustable:
-----------------------------<quote>-----------------------------
.... R5 sets the switching threshold of the second op-amp; normally it
is adjusted so that the circuit barely triggers on background noise,
then it's backed off a bit. The response of the circuit may be tuned
by adjusting the length of the leads on C1. For typical road-radar
systems, the input capacitor's leads should be about 0.5 to 0.6 inches
long.
------------------------------</quote>-----------------------------
So R5 adjusts the sensitivity, and the length of C1's leads set the
frequency.
Cheers!
Rich
