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What was your first circuit? Do you still remember it?
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TimFox:
Mine was a code-practice oscillator that I built in Cub Scouts, ca. 1960, similar to the one in the QST article linked below.
It used a CK722 PNP germanium transistor from Raytheon.
That, and the GE 2N107 NPN transistor, were heavily advertised to young people at that time.
IIRC, they were both about $2.50 each back then.
https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1959/07/page30/index.html
brucehoult:

--- Quote from: themadhippy on November 26, 2022, 02:06:41 pm ---
--- Quote ---How on earth can you have a DPDT switch with only 4 terminals?
--- End quote ---
Take a look at your diagram,theirs only 4 external connections needed ,and thats what you buy off the shelf from your electrical supplier,they go under the name of intermediate switch and do exactly what you described above,sit between  2 way switches to add a 3rd,4th -999th switching position.They really should rename them universal switch as they can be used for the most common switching arrangements found on lighting circuits.

--- End quote ---

Well great if this is common enough they make specialised switches for this. I've only seen general-purpose DPDT switches, but I'm a hobbyist doing low voltage stuff not a sparky, and 6 terminal DPDT switches are possibly the MOST common kind.

https://sparks.gogo.co.nz/catalog/Buttons-Switches-Relays-261/Miscellaneous-100/DPDT--AB--Small-Panel-Mount-Toggle-Switch-6mm-Thread-1015.html


TimFox:
A DPDT switch hard-wired to only four terminals is often called a "reversing switch", or in US domestic lighting a "four-way switch", which is connected between two or more "three-way switches" (SPDT) to control lighting along a corridor, etc.
themadhippy:

--- Quote ---.6 terminal DPDT switches are possibly the MOST common kind.
--- End quote ---
in the electronics world agreed,however what surprised me is

--- Quote ---but I noticed the switches being installed were actually DPDT.
--- End quote ---
as ive yet to see a dpdt switch in a standard light switch  format
mawyatt:

--- Quote from: TimFox on November 26, 2022, 06:42:34 pm ---Mine was a code-practice oscillator that I built in Cub Scouts, ca. 1960, similar to the one in the QST article linked below.
It used a CK722 PNP germanium transistor from Raytheon.
That, and the GE 2N107 NPN transistor, were heavily advertised to young people at that time.
IIRC, they were both about $2.50 each back then.
https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1959/07/page30/index.html

--- End quote ---

Remember those CK722s, one of the early plastic cased transistors. You could shine a light on them and they responded!!

First project here was a telegraph made from old scavenged lantern batteries, scrap phone wire, tin can top, scrap nails and scrap wood 2 by 4s. Tin top was cut for telegraph "key" with nail contact, and the "T" shaped "sounder" and wire wound around 2 nails as electromagnet. Was 6~7 then and parents thought I was nuts, they were probably right :o

Fond memories from back then!

Best
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