Strangest component i have seen so far

the red one in the front.
is that a cap?

its in a device i took apart to repurpos the awesome switches and knobs and the front panel.
its a medical device (cardioscript) from the pre transistor era. now i am curious, what that red thing is.
some of those metal plates seem to be connected to some windings of the bigass transformer that is part of the psu.

The red device isn’t a capacitor. It is a selenium rectifier. Those were used before efficient diodes available

Ca i please have the 0,5µF Cap from bosch which states “Tropenfest” ? If i can get hold of 8 of these ill try them in a SMR-4

thanks cybaer! i didn’t know about those.


there are quite a few caps in there…

i think the whole device is “tropenfest” by the way :wink:

Weird, some of the capacitors have an old Draeger logo printed on it. Was it a medical device from Draeger? I’m working for over 20 years for that company but didn’t know that they made their own caps back in the days.


no it is not from Draeger, but it’s a Medical Device - a Cardiograph
The Enclosure says it is from “Elektrofrequenz Fritz Schwarzer GmbH”

I Haven’t figured out, when it was Manufactured though. The Style of the Enclosure and Panel looks like 50s/60s.

I bought it (8€) to use the switches and knobs and the front panel because they look awesome and the haptics of the Buttons and Switches feel just incredible. I think i’ll build a Spring reverb in a wooden Enclosure with it.

…according to this they started to build those kind of devices from 1948 and started with digital ones from 1973. so some time in the 50s/60s seems right.

i’ve salvaged a lot of electromechanical parts from old tube radios / tape machines. they have totally weird switch banks, those big ones almost like piano keys. would be funny to use them in some noise machine or something.
ah btw has anyone come across a use for those big adjustable capacitors that are in the old radios (to dial the frequency)? basically they’re just layers of metal plates that are moved in between each other to increase/decrease capacity. the good thing is other than pots they never wear off because there’s no friction. but i guess one would have to be lucky to find one with a usable value for eg a resonance feedback path etc

you could use them as adjustable decoupling cap…… just add some gold wires and wooden side panels :wink:

hey cool a breakout box for decoupling caps, to get the best audiophile[TM] bang out of every IC!

did anybody say banana jacks?

just plain banana won’t do. have to be laboratorium[TM] grade platinum body and gold plated.

Hi! I have the option to cannibalize several Sony Professional U-Matic Video Tape Recorders/Players. Does that make sense? Might there be something DIY-interesting inside?

Are they really dead?

I think they are only obsolete. And they are heavy and they are wasting room.

A friend of mine bought them from a studio 20 years ago. And since then they are waiting for better times.

It doesn’t go any better than U-Matic…… but i think you can grab some transformers from them that easily can power the ITER project…

O. K. Perhaps I start with collecting the knobs from the frontpanel then… I´ll have a look. I just saw that some of these recorders are sold on ebay in the range from 1 Euro up to 200 Euro.

200€ is approx the sheer metal value….

Yes… something reminds me of these subway trains that were sunk as artificial reefs. Have to have a look at the garden pond…