Walnut Base Carborundum Crystal Radio Diode Detector Stand Brass and Bias Diode

Description

Carborundum C
rystal Radio Diode Detector Stand Solid Walnut Wood Base Brass with Bias Diode
Crystal Radio Diode Stand in Walnut Wood Base, Brass Hardware and Torsion Whisker
Includes my Exclusive Design Preformed Torsion Cats Whisker
Torsion Cats Whisker:
Silver Plated
Beryllium Copper
New torsion spring design allows a constant, higher force that required by a Carborundum Crystal
Easy Screw Adjustments are secure with a more stable contact to the Crystal
Brass Knurl Nuts for Quick and Easy connection to your Radio
Bamboo Wood Base - Smooth Polished Finish and Warp Resistant
Note:
DOES NOT
INCLUDE GLASS DOME
This New Design uses a High Performance Germanium Biasing Diode to decrease the forward drop across the mineral crystal.
The Forward Biasing Diode can be easily removed, but you will loose all the benefits of lowering the forward drop of the Mineral Crystal.
Crystal Radio Detector Stand and Crystal with
Newly Designed Brass Fittings
Working with a Cats Whisker and Crystal can be very tricky and takes a great deal of patience, time, steady hands and acquired skills.
The surface of the crystal form a crude and unstable point-contact metal–semiconductor junction that acts like a diode, current can flow from the wire into the crystal but not in the other direction.
Operation: To change the contact position, gently lift the end of the whisker wire at the contact point and slide the crystal cup. Just lift the whisker slightly 1/16" from the top of the crystal surface and only then slide the cup. Don't slide the crystal cup while tension is being applied from the whisker wire as this crumbles some crystal surface particles and makes the contact point even more unstable.
The most common type was the so-called cat whisker detector, which consisted of a piece of crystalline mineral with a fine wire touching its surface.
The old ball designs are not at all mechanically stable when attempting to adjust them, I have tested these and they just didn't work well with my experiments.
X and Y axis control can be made by lifting the whisker ever so slightly 1/16" from the crystal surface and sliding the crystal cup in any direction.
Z axis (up and down) control can be achieved easily by just cutting a small amount from the end of the whisker. (Just dont cut off too much or the whisker will be too short to properly contact the crystal surface.
It is also possible to form a small turn, bend or loop in the whisker wire to achieve proper Z axis control and this also may change the spring force of the whisker. You can also put a small bend at the tip of the whisker wire to make better contact at 90 degrees from the whisker surface.
Replacement whisker wire is available.
Base Dimensions:
Diameter: 4" Base
3/8" Thick
Total
Height
: 2"
Base is Made of Solid Walnut
Easily replaceable Whisker and Crystal
3 Silicone Rubber feet on base
1
Crystal Detector ( Actual crystal may vary in shape and size from picture)
1 Torsion Cats whisker pre-installed in the mount (see more instructions below for forming a whisker)
Crystal mounted and Cast in a 13mm" Diameter brass cup
(The Crystal Cup is gently secured and centered to the Base Plate with a conductive Adhesive.)
(You can remove it easily but will loose Cup movement Stability.)
Casting alloy is made from Lead, Tin and Bismuth-Cadmium Free
Includes a Torsion "Cats Whisker".
Positive spring whisker contact, screw-feed position adjustment and sliding cast cup Crystal
Fully assembled, tested and ready to go.
FACTS ABOUT OLD SCHOOL CRYSTAL DIODES
Measuring forward and back resistance ratios of crystal-and-cats-whisker diode. There is a significant difference
between forward and back resistance readings on an ohmmeter, but the ratio was nowhere close to that of a modern germanium diode,
thus limiting the efficiency of the crystal. However, connecting a germanium diode as a bias with the crystal can make a major
improvements in performance.
Not every contact position on the Galena crystal will perform, so fiddling with the ‘cat's whisker’ to find a sweet spot does take patience and a steady hand.
position to find a sweet spot on the crystal does take patience and some acquired skill.
To change the contact position, gently lift the end of the whisker wire at the contact point and
slide the crystal cup.
Don not bend the whisker too much or it will take a bend and loose the spring tension.
Just lift the whisker slightly 1/16" from the top of the crystal and only then slide the cup.
The "cat whisker", a springy piece of thin metal wire, Hardened wire of about 30 gauge is
commonly used.
The wire whisker is the anode, and the crystal is the cathode.
Cat Whisker:
The "cat whisker", a springy piece of thin metal wire, formed the metal side of the junction. Hardened wire of about 30 gauge was commonly used because it had the right amount of springiness.
Crystals that require a light pressure like Galena and Pyrite were used with the wire cat whisker contact; silicon was used with a heavier point contact,
while Silicon Carbide (Carborundum) could tolerate the heaviest pressure.
Different crystal minerals require just the right amount of pressure by the wire to work; too much pressure causes the device to conduct in both directions.
Cat whisker detector:
It consisted of a pea-size piece of crystalline mineral in a metal holder, with its surface touched by a fine metal wire or needle (the "cat whisker"). The contact between the tip of the wire and the surface of the crystal formed a crude unstable point-contact metal–semiconductor junction, forming a diode. The wire whisker is the anode, and the crystal is the cathode; current can flow from the wire into the crystal but not in the other direction.
Having a lot of patience and a steady hand are needed when you listen with a piece of the rock. But this can also be very rewarding when you can hear the first station using a cats whisker detector.
Please note : This item not a Crystal Radio, but is installed into a Crystal Radio and used to replace a modern Germanium diode with an older technology developed during the 1920's.