Historical cat's whisker designs - Revision history

Cornish semiconductor at 12:46, 21 June 2026

2026-06-21T12:46:19Z

← Older revision		Revision as of 12:46, 21 June 2026
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	[[File:Radio-close.jpg]]		[[File:Radio-close.jpg]]

	It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact ~~idea~~ - but is fixed and much smaller:		It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact method - but is fixed and much smaller:

	[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|center\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]		[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|center\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]

	~~This~~ is another variant of ~~the~~ horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs. Sometimes the crystals are fixed mechanically with set screws, more often with wood's metal, a toxic alloy that melts at a low temperature to avoid ~~damaging~~ the crystal material.		Here is another variant of horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs. Sometimes the crystals are fixed mechanically with set screws, more often with wood's metal, a toxic alloy that melts at a low temperature to avoid altering the crystal material.

	[[File:Horizontal.jpg]]		[[File:Horizontal.jpg]]
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	[[File:ArmType.webp\|500px\|center]]		[[File:ArmType.webp\|500px\|center]]

			A vertical arrangement, that seems (although it's difficult to tell) to align two crystals together, presumably a perikon like setup. "Perikon" was the name given to combining chalcopyrite and zincite, which apparently provided a very effective diode behaviour.

			[[File:Vertical.jpg\|500px\|center]]

	===Multi crystal sets===		===Multi crystal sets===
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	[[File:Double.jpg\|center]]		[[File:Double.jpg\|center]]

	This is a piece of equipment specifically for testing crystals. It's unclear but possibly the one on the left is for testing two crystals brought into contact with each other~~. "Perikon" was the name given to combining chalcopyrite and zincite, which was made in this way~~.		This is a piece of equipment specifically for testing crystals. It's unclear but possibly the one on the left is for testing two crystals brought into contact with each other.

	[[File:Multi.webp]]		[[File:Multi.webp]]

Cornish semiconductor: /* Historical variants found on ebay listings */

2026-06-21T09:13:17Z

Historical variants found on ebay listings

← Older revision		Revision as of 09:13, 21 June 2026
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	[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|center\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]		[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|center\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]

	This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs.		This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs. Sometimes the crystals are fixed mechanically with set screws, more often with wood's metal, a toxic alloy that melts at a low temperature to avoid damaging the crystal material.

	[[File:Horizontal.jpg]]		[[File:Horizontal.jpg]]
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	[[File:Marconi2.webp]]		[[File:Marconi2.webp]]


	==Modern builds==		==Modern builds==

Cornish semiconductor at 09:11, 21 June 2026

2026-06-21T09:11:43Z

← Older revision		Revision as of 09:11, 21 June 2026
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	It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact idea - but is fixed and much smaller:		It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact idea - but is fixed and much smaller:

	[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|~~left~~\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px~~\|center~~]]		[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|center\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]

	This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs.		This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs.

Cornish semiconductor at 09:11, 21 June 2026

2026-06-21T09:11:19Z

← Older revision		Revision as of 09:11, 21 June 2026
Line 14:		Line 14:
	It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact idea - but is fixed and much smaller:		It's a horizontal setup and protects the crystal with a glass envelope. You can clearly see a direct link to modern components like this germanium diode, which still uses the point contact idea - but is fixed and much smaller:

	[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|left\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px]]		[[File:EFD108_Point_Contact_Germanium_Diode.jpg\|200px\|thumb\|left\|Mister rf, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons\|500px\|center]]

	This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs.		This is another variant of the horizontal construction, there were probably as many varieties of these as there were companies manufacturing radios (several hundred) including home made designs.

Cornish semiconductor at 09:10, 21 June 2026

2026-06-21T09:10:25Z

← Older revision		Revision as of 09:10, 21 June 2026
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	Crystal radios from the 1920s are still possible to get hold of, but can be quite expensive. They contain a wide variety of approaches to mounting a crystal (usually, but not exclusively galena) and the cat's whisker, and attempts at making them adjustable and adding stability at the same time. This is a collection of photographs and diagrams I've managed to find online. The materials used correspond with what was available at the time, glass and metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years.		Crystal radios from the 1920s are still possible to get hold of, but can be quite expensive. They contain a wide variety of approaches to mounting a crystal (usually, but not exclusively galena) and the cat's whisker, and attempts at making them adjustable and adding stability at the same time. This is a collection of photographs and diagrams I've managed to find online. The materials used correspond with what was available at the time, glass and metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years.

	On the right is a diagram of a vertical set up found on [https://www.radiomuseum.org\|radiomuseum.org]. This design doesn't seem to allow for positioning of the point contact, only the overall pressure - which to be fair is generally more important.		On the right is a diagram of a vertical set up found on [https://www.radiomuseum.org radiomuseum.org]. This design doesn't seem to allow for positioning of the point contact, only the overall pressure - which to be fair is generally more important.

	==Historical variants found on ebay listings==		==Historical variants found on ebay listings==

Cornish semiconductor at 09:09, 21 June 2026

2026-06-21T09:09:47Z

← Older revision		Revision as of 09:09, 21 June 2026
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	[[File:Marconi.webp]]		[[File:Marconi.webp]]

	Instead of a cat's whisker, the carborundum is fashioned into a point that makes contact with a metal plate - so the inverse of the galena point contact. The contact pressure can be adjusted with a thumb screw - this image show the parts disassembled. It seems a common feature of these devices to be easily		Instead of a cat's whisker, the carborundum is fashioned into a point that makes contact with a metal plate - so the inverse of the galena point contact. The contact pressure can be adjusted with a thumb screw - this image show the parts disassembled. It seems a common feature of these devices to be easily taken apart and put back together, something we are only now rediscovering is important.

			This radio also features something very unusual - a battery! This was used to provide a DC bias voltage to improve the galena crystal. I think to push the conductivity into the active region to remove the voltage drop that stops it passing current below a certain threshold. In my experience this varies across different point contacts, so would have been tricky to 'tune' correctly.

	[[File:Marconi2.webp]]		[[File:Marconi2.webp]]



	==Modern builds==		==Modern builds==

Cornish semiconductor at 09:01, 21 June 2026

2026-06-21T09:01:32Z

@@ Line 1: / Line 1: @@
-[[File:Catswhiskerdiagram.png|right]]
+[[Category:ACE R&D]]
-Crystal radios from the 1920s are possible to get hold of, but can be quite expensive. This is a collection of photographs and diagrams of crystal/cat's whiskers setups that I've managed to find. The materials used correspond with what was available at the time, glass, metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years.
+Crystal radios from the 1920s are still possible to get hold of, but can be quite expensive. They contain a wide variety of approaches to mounting a crystal (usually, but not exclusively galena) and the cat's whisker, and attempts at making them adjustable and adding stability at the same time. This is a collection of photographs and diagrams I've managed to find online. The materials used correspond with what was available at the time, glass and metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years.
-On the right is a diagram of a vertical set up. This design doesn't seem to allow for positioning of the point contact, only the overall pressure - which is generally more important.
+On the right is a diagram of a vertical set up found on [https://www.radiomuseum.org|radiomuseum.org]. This design doesn't seem to allow for positioning of the point contact, only the overall pressure - which to be fair is generally more important.

Cornish semiconductor: Created page with "right Crystal radios from the 1920s are possible to get hold of, but can be quite expensive. This is a collection of photographs and diagrams of crystal/cat's whiskers setups that I've managed to find. The materials used correspond with what was available at the time, glass, metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years. On the right is a diagram of a vertical set up. This..."

2026-06-20T07:15:39Z

Created page with "right Crystal radios from the 1920s are possible to get hold of, but can be quite expensive. This is a collection of photographs and diagrams of crystal/cat's whiskers setups that I've managed to find. The materials used correspond with what was available at the time, glass, metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years. On the right is a diagram of a vertical set up. This..."

New page

[[File:Catswhiskerdiagram.png|right]]

Crystal radios from the 1920s are possible to get hold of, but can be quite expensive. This is a collection of photographs and diagrams of crystal/cat's whiskers setups that I've managed to find. The materials used correspond with what was available at the time, glass, metal but also the first plastics, ebonite and bakelite - which would have felt very futuristic in these years.

On the right is a diagram of a vertical set up. This design doesn't seem to allow for positioning of the point contact, only the overall pressure - which is generally more important.