dave wrote:

On 01/24/2014 03:22 PM, Michael A. Terrell wrote:

dave wrote:

On 01/23/2014 06:05 PM, Michael A. Terrell wrote:

dave wrote:

On 01/23/2014 06:45 AM, Michael A. Terrell wrote:


It is not a switch or a valve.


It's a solid state diode that oscillates. DC in, and ~10 GHZ out.
Search on Gunnplexer. You see them on automatic doors in almost every
store. A microwave mixer diode takes a sample from the Gunn diode and
compares it to any reflected signals. This results in a low frequency
signal that is detected, amplified and signals the door to open. How
can a passive diode do that?


Like I said. You can hit a piece of quartz with a hammer and it will
oscillate; that doesn't mean it's considered and active device.


No, it will crush the quartz, resulting in one spike as it breaks up.


An active device uses one signal [current, voltage] to control another.


Like a 'Carbon Amplifier'?


As in amplify or switch. Thermionic valve, transistor, SCR, Triac is
what we are going for.


A rectifier is a switch. Diodes are used as mixers, and the
rectifiers a poorly designed power supply can generate RF that is
coupled into the power line.


Sigh. Small minds like yours will never learn anything.


Oscillators do not use one signal to control another. A Gunn diode is a
lot like a neon lamp meets quartz crystal. Not a switch. Not an amplifier.


Sigh. Study that technology, rather than make a fool of yourself.
The proper bias creates a negative resistance, which provides gain.


A neon has hysteresis, not gain. They require a current limiting
resistor, or they will explode. They turn on at a higher voltage than
they turn off so a capacitor across the neon will charge, until the lamp
fires. The cap discharges to the extinguishing point, and repeats the
cycle. We built sirens with a couple neons, a 35W4 and a 50C5 tube back
in the '60s


It's a relatively stupid minor point. I looked it up. I am not going to
be convinced with silliness like "carbon amplifiers".


It's not silly. They were used to provide gain in early days of
electronics. It was a carbon mic, coupled do a earpiece. They had plenty
of gain. Find an old 500 series desk phone and pull the cotton wadding
out of the handle. You'll get feedback. Then there are Magnetic
Amplifiers. There is a whole world of electronics you've never seen.
How about 'Electrolytic Rectifiers'? They were one of the first crude,
but useable ways to convert AC to DC without using a motor/generator
set.