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Bought some old speakers from ebay - here's what I found inside
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MrMobodies:
 
--- Quote from: DrG on May 16, 2021, 09:51:45 pm ---You could make a schematic :)

--- End quote ---



I remembered when I believed I use to recognize actors from pictures many years ago doing things like exploring abandoned buildings but no name apart from the teams who were regular in their exploration so I used this tool a number of times to see if their face match from their official photographs.

Peekthrough
https://www.lukepaynesoftware.com/projects/peek-through/

Hope the attached images helps (with different transparency levels) for someone who wants to do a schematic and would be interesting to draw it on Falstad.
themadhippy:

--- Quote ---I was curious as to what that was and found it in a 1978 Fairchild catalogue.
--- End quote ---
no need to go back to 1978,its still widely available today.
MrMobodies:
OOps I got a bit confused, "F 4013BPC" I believed I might have also made a mistake at some point which is why not much came up and looking at my history the "f" got lost somewhere leading me to that 1978 magazine. So I got the wrong part number so sorry about that. Will amend my post.

I notice some with a space inbetween the F.

F 4013BPC
https://www.ebay.com/itm/F4013BPC-IC-DIP-4-PIECES-qzty-/282952293885


F4013BPC
https://www.ebay.es/itm/303146097929


I see that putting it in exactly brings up a lot of results from foreign websites.

https://www.google.com/search?q="F+4013BPC"
james_s:

--- Quote from: Benta on May 17, 2021, 09:15:00 pm ---Anti-theft device. the coils and the two caps are resonant circuits for the theft detector at the doors. The IC and resistors are pure camouflage (very usual back then).

--- End quote ---

Camouflage for what? The device is concealed inside the speaker, what would be the point of adding gratuitous components?
Cyberdragon:

--- Quote from: james_s on May 18, 2021, 03:01:43 am ---
--- Quote from: Benta on May 17, 2021, 09:15:00 pm ---Anti-theft device. the coils and the two caps are resonant circuits for the theft detector at the doors. The IC and resistors are pure camouflage (very usual back then).

--- End quote ---

Camouflage for what? The device is concealed inside the speaker, what would be the point of adding gratuitous components?

--- End quote ---

They are all connected properly as the OP said. It is a frequency divider using a flip-flop. The resistors are probably for bias or something. What's odd is there does not seem to be a way to disable the device externally if it is a theft alarm trigger.
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