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I'm trying to date a circuit from an organ. It contains transistors in a TO-92 (plastic) package.

Approximately when did these transistors first appear?

enter image description here

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    \$\begingroup\$ I personally remember plastic TO-92 transistors from the late 1960s, but I'm sure they originated much earlier than that. This is not a useful way to date your board. \$\endgroup\$ Feb 4, 2013 at 14:28
  • \$\begingroup\$ Are there any ICs on there with date codes? For example 7520 (20th week of 1975) or similar. Or check the board carefully for e.g. a date etched in the copper. \$\endgroup\$
    – Oli Glaser
    Feb 4, 2013 at 16:27
  • \$\begingroup\$ I don't have access to the organ just now, as it is a friends' - that is the only photo he gave. I will take a look in the next couple of days to see if there is anything more identifiable. \$\endgroup\$ Feb 4, 2013 at 16:31

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Edit

Thanks for the picture, by any chance are their any identifying text left on the packages or the boards? Just a shot in the dark, but I would say that board was from the aprox: 1972 to 1985. But it depends on so many other factors. And it also my not be original to the organ it'self.


Original Answer

I'm trying to date a circuit from an organ.

It would be the easiest to just look up the organ...

Date of introduction of TO-92 transistors. Approximately when did these transistors first appear?

The TO-92 spec was introduced in the 1960's (I believe but can't find a source,) and became a standard by JEDEC Solid State Technology Association years later.

FYI, none of this information will help you date the organ's board!

It depends on the actual model of the transistor and a few other factors. Semiconductor material (date first used):

  • the metalloids germanium (1947) and silicon (1954)
  • in amorphous, polycrystalline and monocrystalline form
  • the compounds gallium arsenide (1966)
  • silicon carbide (1997)
  • the alloy silicon-germanium (1989)
  • the allotrope of carbon graphene (research ongoing since 2004)
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  • \$\begingroup\$ That is surprisingly late - I was told the organ was a late 50s model. I don't have the organ to hand so can't investigate any further than a photo I have. I will add the photo to my question. \$\endgroup\$ Feb 4, 2013 at 14:03
  • \$\begingroup\$ @c.cam108 1980 was a typo, I meant 1960's. But like I said, can't find a source. I listed the dates of the technology, so maybe that would help. Also I see you just added a picture too. I'll email my father, he would know. Or I can dust off one of my old Motorola parts books... \$\endgroup\$ Feb 4, 2013 at 14:10
  • \$\begingroup\$ Yes 1960s was what my dad assumed when I asked him. Definitely not 1950s though. \$\endgroup\$ Feb 4, 2013 at 14:11
  • \$\begingroup\$ @c.cam108 see my update. (If I was betting on it, it would I would probably go in around ~1974. But just a stab in the dark!) I'm out door now, but I can link a few blogs that you could ask on. They love this type of stuff... \$\endgroup\$ Feb 4, 2013 at 14:16
  • \$\begingroup\$ The resistors look like the ones in my Kosmos set: radiomuseum.org/r/kosmos_radio_elektronik_1.html \$\endgroup\$
    – starblue
    Feb 4, 2013 at 19:37
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Look for date codes on (unlikely) the transistors; (likely) any TO3 transistors in the power supply; definitely ICs if there are any; and (sometimes) large electrolytic capacitors, again in the PSU. Also that screened can (inductor?).

Earlier than 1970 I think the TO18 can would be more common (there's 1 in your picture) and much later, ICs would start appearing (along with 5% resistors rather than 10%) so I doubt it's as late as 1980.

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