Questions tagged [vintage]

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75 views

MRC Variac+ — NEED HELP identifying this antique electronic

I gather, so far, that there is a variac component to this equipment. And that it was manufactured by the MRC Manufacturing Corporation (a Subsidiary of Materials Research Corporation), which once ...
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1answer
47 views

Need Clarification on Choke Placement (Vintage PS)

I came into possession of an old Electro D-612T variable DC power supply. Based on what I've read here and other places it was manufactured in the 1950s, and sold for a whopping $39.95 US at Radio ...
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1answer
56 views

How to create an ATX -5 volt rail for vintage Macintosh

I am trying to build a simple adapter for a mini ATX power supply for a vintage mac, I need a 5 volt rail that has it’s own separate ground (+5 volts to -5 volts) how would I go about doing this?
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2answers
52 views

Trimming a power supply to 0 V output in current limit

Here is another question on the originally Czech bench power supply that I recently built, but in the version¹ of it sold by various places (e.g. eBay) very cheaply. The circuit has two potentiometers ...
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0answers
46 views

Appreciate help in identifying this vintage IC - Fairchild HL41109 QB

Trying to find out what this one is has been a real head-scratcher. Google leads me down numerous rabbit-holes to dead ends. And I see 1 or 2 for sale on eBay, but apparently they have no idea what it ...
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2answers
93 views

How to find a Pin-to-Pin Replacement for TL-081, but with higher VCC? [closed]

After ordering and assembling one of those¹ "red" 0-30V/0-3A power supplies from eBay/AliExpress and taking a bit of a closer look at it, I'd like to replace the TL-081 op-amps. It's working ...
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2answers
82 views

Converting old relaxation oscillator vacuum tube circuit to a more modern circuit?

I am trying to figure out how to convert an old relaxation oscillator circuit from the late 30's. The history of this circuit, is this is the buzz generator for the Bell Labs Voder, which is a speech ...
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2answers
74 views

Finding replacement PNP transistors

Hello and I apologise if my first question is rather basic as I am new to electronics. I have started to repair vintage amplifiers and have found transistors that I need to replace are no longer ...
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1answer
93 views

Can I replace a 101 ceramic capacitor with a close value one?

I'm kind of new to electronics and sorry if this is a bad question. I am trying to repair my father's old radio transmitter and I noticed that the PTT won't pick up your voice. I opened it up and ...
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1answer
116 views

What is this symbol on a schematic for an old milling machine?

On the schematic below, I'm having trouble identifying what the symbol drawn on top of motors 2 and 3 means. I've never seen anything like it. They're only present on the high-power spindle and feed ...
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50 views

Intercepting signals from vintage computer (common ground)

I am trying to reverse engineer the signalling for a peripheral to an old 4-bit computer and eventually I want to emulate the peripheral and send the appropriate signals back to the computer. I know ...
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1answer
62 views

Identify components in an audio circuit schematic

In the attached image you can see a circuit part of a commercial audio amplifier. I'm trying to determine what kind of component is R-CH and what role it plays in ...
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2answers
86 views

Transistor substitution guidelines? (and the BC147A)

I'm in the US and fixing a vintage German integrated amp which has a crackle static issue I've isolated to a transistor in the preamp section. The transistor is specified in the schematic (below) as a ...
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2answers
104 views

Difference between junction points in old schematic

What's the difference between the black circle and the white one in this old schematic? Of course the black ones are junctions, but are the white circles a pin, or an input of some kind? I'm trying to ...
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1answer
79 views

Replace amplifier IC with a class D amplifier (AN7133N with TPA3116 board)

Today I received this nice 90's Panasonic RX-CT900 boombox in the mail. The specs claims it is 2x60W PMPO (PMPO b**llsh*t throw-of- a-cliff specification) but in fact it is just 2x5.5W RMS (...
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1answer
131 views

IPA becoming unobtainium, can I use denatured alcohol to clean vintage computers?

Due to COVID-19 and peoples' practice of hoarding, IPA is becoming incredibly difficult to find where I live (and online). Since we are all home so much these days, I like spending some of that time ...
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3answers
179 views

Can you identify this diode? (vintage audio amplifier)

I am restoring a Japanese Teisco mixing amplifier from the 1970s. It's a solid state 5-channel mixer with 16ohm speaker outs and a line out. Amongst other problems, I have discovered a couple of the ...
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2answers
72 views

ID a green ceramic component from a tachometer?

This component is from a 1960-70 vintage boat tachometer. It's about 1.25" long. It generates not a single reading on my 11-function multimeter (including capacitance). I may have fried it ...
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1answer
106 views

Performance changes to metal can transistors installed 40 years ago

What problems, if any, are to be expected when using 2N4037 metal can PNP transistors that were installed 40 years ago? I can't divulge much about the design, but transistors are in a voltage ...
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1answer
268 views

Repairing power circuit with reverse polarity damage

Recently I bought an old musical keyboard (a Casio HT-3000). It came with a PSU, and when it arrived I plugged it in without paying too much attention, and... nothing but a burning smell. I quickly ...
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3answers
2k views

Are screened transistors an endangered species?

In the germanium transistor era, the RF transistors were PNP small signal devices. Some of these small metal cased BJTs had 4 leads instead of the usual 3. The metal can was isolated and the 4th ...
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1answer
38 views

Capacitor ID? Polar or Nonpolar?

I have been trying to repair an old 14 transistor radio from the mid-60's and have no sign of any image of the radio or schematics for it online. One step I'm taking is to replace old caps (mostly ...
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2answers
1k views

Fixing old CRT oscilloscopes… what to look for first?

I've been amassing a pretty large collection of these old scopes, and it's about time I got to trying to fix them. About half of the ones I run across and buy don't have traces. I don't need to get ...
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0answers
159 views

Russian germanium transistors

The germanium transistor era was long over in the west when the Berlin wall came down. Nowadays, new old stock Russian germanium transistors are appearing on world markets. Some musicians prefer ...
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1answer
90 views

Why do they not make center tapped loadspeakers?

An early Australian solid state portable receiver manufactured by AWA used a 30 ohm centre tapper speaker that was directly driven by a push pull PNP germanium output stage. The orthodox arrangement ...
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3answers
137 views

Can I replace a dual section capacitor in a tube amplifier design with two single capacitors?

I was planning on building this schematic, but found it hard to source their 20/20 dual section cap (C3/C4). Could I replace this with two single 20uF caps, or is it a dual-section for a reason?
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2answers
110 views

Ferrite rod antenna improvements

Most early solid state portable MW AM radios used a ferrite rod antenna. Some valve receivers like Phillips in the late 1950s used ferrite rods also. The early Germanium RF transistors were not too ...
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1answer
64 views

Envelope Detector Improvements?

The classic Envelope Detector is very old and very cheap and very simple .Sure there are now better schemes like synchronous detection ,PLL etc.The circuit is responding to the peak of the Amplitude ...
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1answer
5k views

Why were germanium diodes so fast and germanium transistors so slow?

Germanium diodes were used for Radar during WW2. Germanium transistors appeared about a decade later. Most early transistors were only specified for audio use, like the OC71. The specified RF types ...
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1answer
119 views

Identify component in 1970s vintage video game from photo

Can anyone identify these two components, marked "SKY 4433" and "2.000000 K.D.S", respecitvely? Are they capacitors, crystals, or something else? They are from a vintage 1970s ball-and-paddle-style ...
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2answers
142 views

Why do older (green) PCBs have primarily a darker color, whereas new ones are lighter

Note the difference in color between this old commodore board and this newer board. It might seem like lighting, but after looking at my own collection of scrap boards, the older ones tend to have a ...
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1answer
80 views

What is an impedance bridge?

Today, I saw a very old historical piece of lab equipment at the university. It had a large number of dials, although not as large as you would see in an oscilloscope. The size was similar to an ...
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1answer
199 views

What are these hybrids from National Semiconductor?

I found some parts in my junk drawer that I can't identify. I'm pretty sure they're National Semiconductor hybrid circuits from 1969-1970, but I have no access to a National Hybrid Products databook. ...
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34 views

Volume control reliability

Log potentiometers were the mainstay for volume controls in radios .I have seen values of 5 to 10K in early solid state radios .Valve radios would use 250K to 1 meg .Crystal cartridge record players ...
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2answers
1k views

RIFA PME271M547 replacement

I just broke my sewing machine (it's an old Viktoria machine about 30-40 years old) and now I am looking for a replacement safety capacitor. The one installed is a RIFA PME 271 M 547 paper capacitor. ...
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2answers
272 views

EM Vs PM Speaker

Modern Speakers have permanent magnets and are called PM speakers.Permanent magnet materials technology has improved a lot over the last 80 years .Around WW2 EM speakers were common because permanent ...
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1answer
102 views

Design questions regarding LM2735 (boost-converter) for DC-DC

I'm doodling with a future circuit. The application (Commodore 64) expects 5VDC (which I will provide with a pass-through) and 9VAC 50Hz. I do not have any working circuit or a schematic, because the ...
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2answers
405 views

What connector did this IBM Model M keyboard have?

I got got hold of an old IBM Model M (Model 1391403, to be precise). Unfortunately, the fixed cable was cut off by an unknown idiot. Does anyone know what kind of connector (I assume PS/2?) was ...
2
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1answer
124 views

old 80C31 circuit not working. EPROM data retention issue?

I have an old piece of pro-audio gear in for repair. It dates from 1990. It was a fairly high-end piece of gear at the time and still has some value so it is worth repairing. But the symptoms I see ...
2
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1answer
180 views

Can old vintage quartz crystals handle more power?

Old crystals are very large compared to present day devices. Vintage transmitter circuits did not have many valves in their line up. I have seen a 2 valve 50 watt CW transmitter for 80 meters in a ...
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1answer
539 views

Identify Vintage Power Cord for 1980s Organ [closed]

I Recently acquired a Technics SX-C600 organ but it needs a power cord. Does anyone know what type of power cord I should get for this? My understanding is that this is a rare organ.
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1answer
123 views

How does a rocking arm voltage regulator work?

I am trying to determine the suitability of replacing a (ancient) rocking arm voltage regulator with a modern digital device. I assume a rocking arm regulator has an electromechanical or magnetic ...
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1answer
49 views

Increase rotational velocity of synchronous motor

I recently got my hands on a Philips PM8110 (a single pen recorder which is basically an analog printer for voltages) which sadly provides paper with a velocity of 8 cm/hour. Although this would ...
14
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1answer
637 views

Old equipment to identify

I volunteer at the Dauphin Railway Museum in Manitoba, where we recently received a donation of equipment collected by CNCP Telecommunications in the 1970s and earlier. Most has been identified, ...
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0answers
123 views

Please help identify this vintage component [closed]

I got this item in a bidding lot and have been trying to figure out what it is ever since. The nearest I can tell it is either an electro shock therapy device or perhaps a remote detonator. It has ...
14
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1answer
2k views

What is a “universal bridge”?

I recently came across this intriguing instrument from the 1970s(?): It's a "Universal Bridge" made by Wayne Kerr. It's not a type of device I've come across before and I'm curious what these are (...
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2answers
256 views

Old-school pseudorandom pulse generator (requesting assistance with hardware design)

I would like to design an old-school pseudorandom pulse generator to trigger various types of events (hardware suggestions only please - no programmable ICs). The events that I want to control need to ...
9
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2answers
645 views

Identifying an old RF circuit

I got an old RF circuit (I guess), probably used for pedagogical purposes. Here's the schematic: I chose the positive and ground rails as it seems right to me, looking at transistors and resistor ...
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7answers
1k views

What kind of capacitor blew up in my old IBM monitor?

I pulled this out of an old IBM 5154 EGA monitor from the 80's. Clearly both are bad (though the monitor itself works anyway...). I know they're capacitors, but what kind? What would a replacement for ...
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1answer
88 views

Stereo Enhanced Mono

Medium Wave AM in most countries is monophonic. AM stereo was never universally adopted. Given a monophonic signal, how can one create a stereo output? I know there are some 'tricks' you can play on ...