In sci.electronics.design piglet wrote:
On 12/12/2020 4:49 am, Don wrote:
The earlier Callins link was only for reference to give people an idea
of the price and physical characteristics.

My questions actually pertain to a 100 μF 6 V Callins, which looks
identical. It's used in a PAIA VCO module from the 1970s. The
schematic's shown he

https://crcomp.net/paia/2720-2A.png

C7 is the Callins. C6 is a plain vanilla electrolytic in a can. They
both have a value of 100 μF.

Although the simpleminded answer goes through everyone's mind first, it
doesn't add up. Why pay more for a Callins back in the day? Why not buy
twice as many electrolytics in cans to get a better price break?
Or, if Callins was the cheap alternative back then, why pay more
for electrolytics in cans?

Perhaps the answer's as simple as the late John Simonton inheriting a
pile of Callins. It's too late to ask John, but there's a PAIA forum,
which may supply some answers, provided they process my registration.
For the time being, the Callins will be substituted with a new
electrolytic in a can.

Danke,


I have some similar epoxy sealed aluminum electrolytics from the mid
1970s made by Roederstein (now incorporated into Vishay). At the time
they cost only a few percent more than metal can/elastomer seal
capacitors. There is absolutely nothing special about the electrical
characteristics needed of C6 and C7 in that unsavoury circuit and my
guess is that the assemblers just randomly picked that brand.

Thank you for confirming my suspicions. It turns out there's a typo on
the schematic. The actual Callins capacitor on the board is 25 V.

As an aside, perhaps the circuit's relaxation oscillator looked a little
less unsavory back in the hazy 1970s, back when Woz won Bushnell's
bonus to minimize the chip count.

Danke,

--
Don, KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.