77
votes
What happened to electrolytic capacitors in the 21st century?
There was a period of time where lots of capacitors were made with a dodgy electrolyte, especially by some large Taiwanese manufacturers. The capacitors looked OK in a wide variety of tests when new, ...
- 12.3k
58
votes
Accepted
Why were germanium diodes so fast and germanium transistors so slow?
Major factors affecting bipolar transistor frequency response include:-
minority carrier transit time
junction resistance
junction capacitance
These can all be reduced by reducing the physical ...
- 56.8k
53
votes
Accepted
Amplification before tubes and transistors were invented
It wasn't.
In the early days (ca 1890) long-distance telephony was done from sound-proofed booths and often using non-standard (4-wire) telephones. New York to Chicago was the limit on range. By 1911,...
- 60.8k
40
votes
Amplification before tubes and transistors were invented
Amplification, before tube amplifiers were available, could be achieved in several ways. Some of them are:
Using a electrodynamic speaker coupled to a carbon microphone, to form a repeater.
Using the ...
- 5,367
33
votes
What happened to electrolytic capacitors in the 21st century?
Industrial espionage gone wrong. Verified many years after the fact.
Though it was suspected from nearly the beginning. (Article courstesy of The Wayback Machine, since the original is gone from ...
- 73.1k
24
votes
Can you help me identify this manufacturer's logo on this component
As TypeIA suspected, this is a Standard Rectifier Corporation diode. The logo below is from Electronics, Feb 3, 1961, page 81.
- 2,936
23
votes
Accepted
Why does this vintage DRAM chip enable circuit require such a beefy resistor?
Am I missing something in my understanding of the switching function of Q1?
No.
Am I missing something in my understanding of the resistor sizing?
Not in the value vs. supply voltage vs. power ...
- 46.7k
23
votes
Accepted
What is this "/|\" symbol on the enclosures of various appliances?
The Broad Arrow (aka 'pheon') indicates that the item in question was once (British) Government property - a Crown asset.
22
votes
Are there special protocols one should take when handling vintage/old electronics?
A loose list. I'm torn between this question being far too broad and far too interesting.
What I shall clearly not do is address the physiological effects of chemical compounds. Just so much: don't ...
- 98.4k
22
votes
Amplification before tubes and transistors were invented
The funnel you're supposed to yell into is actually a horn:
Horns are acoustic transformers, they are usually used the other way around: a high-pressure transducer ("compression driver") is mounted ...
- 80.3k
20
votes
Accepted
What's this vintage diode(?) from the 1970s?
initial thoughts
Every part in this circuit is doing something useful. Some of them are doing more than one thing. It's a minimal class-AB/class-B output stage, with voltage gain. I'll try and cover ...
- 12k
19
votes
Accepted
Why does this diode/capacitor combination appear on every board in a vintage computer?
The diodes are reverse voltage protection. They conduct if the voltage is reversed shorting out the supply enough to blow a fuse or trip a crowbar. It’s done this way rather than a series diode to ...
- 26.1k
18
votes
Amplification before tubes and transistors were invented
The pre-vacuum-tube telephone system used exactly the carbon-granule microphone as the amplifier. What Bell invented was the use of essentially the same device as speaker and microphone. Now we call ...
- 321
16
votes
A story behind a weird inductor
It's a once very common horizontal linearity adjstment for CRT raster scan TV sets.
It basically uses core saturation to achieve a somehow current dependent inductance. Bias magnet just changes ...
- 3,241
16
votes
Accepted
What kind of capacitor blew up in my old IBM monitor?
What you have there are metallized impregnated paper capacitors made by KEMET.
Here is a datasheet of the parts.
The most important thing you have to look for is the capacity rating which should be ...
- 17.9k
16
votes
Accepted
What is this component? 1970s electronics
What Is This Component?
It's the outer magnetic coil of a reed relay. The two axial connections connected into the glass body are for the reed contact: -
The picture above shows the coil (bottom) ...
- 467k
16
votes
Accepted
Can you help me identify this manufacturer's logo on this component
It could be a Standard Rectifier Corporation 240E10,R. It appears in this June 1960 catalog. The company seems to be defunct: it was registered in 1960 and then its registration was surrendered in ...
- 2,437
15
votes
Amplification before tubes and transistors were invented
Telephones are older than vacuum tubes and of course transistors. How
was signal amplification done?
I remember when I was a kid you could buy a plastic handset that connected to another plastic ...
- 467k
15
votes
Accepted
Replacing 1960s Motor Capacitor - Vintage Sewing Machine
Motors for household sewing machines are typically universal motors - they have brushes and run on DC as well as AC. A universal motor doesn't have a start or run capacitor like some AC motors
The ...
- 73.1k
14
votes
Accepted
Can anyone help identify this mystery integrated circuit?
Most likely a resistor network. This would be an uncommon color for an integrated circuit. CTS doesn't presently make integrated circuits, but they still make resistor networks. I can't decode the ...
- 16.6k
14
votes
Accepted
Identify this type of diode from the 1970s (1.3V forward)?
I'm going to take a wild-a** guess and suggest this is a stabistor that is intended to allow the use of a non-Hg battery after trade in those cells became restricted (typical mercury battery voltage ...
13
votes
Accepted
Fixing old CRT oscilloscopes... what to look for first?
Get ahold of the service manuals first. Make sure you are experienced enough to be comfortable working safely with multi-kV voltages such as all CRT scopes use. There is quite enough voltage and ...
13
votes
Accepted
Is there a name for this vintage 3-pin connector configuration?
Jones plug, 303 format, as made by Cinch (which acquired Jones in the 1940s):
https://belfuse.com/resources/datasheets/cinchconnectivitysolutions/industrialcinch/ds-ccs-ind-jones-plugs-300-series.pdf
...
- 4,602
12
votes
A story behind a weird inductor
In old tv sets you find a vertical and horizontal deflection system realized with inductors round the neck of the tv tube. The part in the picture comes from the horizontal or line deflection system.
...
- 3,940
12
votes
Accepted
What do "cycles" in a capacitor mean?
It's your mains frequency (cycles per second). And MFD means microfarads, which you probably know already. You won't find a spec like that on the capacitor datasheet.
That's really, really old. 25Hz ...
11
votes
Are there special protocols one should take when handling vintage/old electronics?
Try not to eat too many soldered joints. That should take care of the lead problem.
High voltage capacitors used to be filled with poisonous PCB oils until (quite) recently.
RF transistors often use ...
- 171k
11
votes
What kind of capacitor blew up in my old IBM monitor?
It's a line filter capacitor, an X2. That series has a reputation for failure after a number of years and you can find other pictures like yours on the internet. The dielectric is paper soaked with ...
- 2,207
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