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Author Topic: Topology?  (Read 430 times)

W2EAF

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Topology?
« on: September 06, 2021, 08:40:49 AM »

I was wondering when the term "topology" came into common use when describing the layout of circuits. Back in the mid 60's through mid 70's I was very into the electronics hobby, read every article and construction project I could find, but never came across that term as I remember. Then in the late 90's, when I got back into things, the first book I bought about electronics in all those intervening years was "Tonnes of Tone", about guitar amps. That's when I first encountered the term topology, and it was used heavily in that book. Another thing from that book was the designation of component values....a 4.7uF cap was called a 4U7, a 4.7k resistor was a 4k7, etc. I wondered if this was a European type designation (even tho the book was published in Canada).
So, did topology become a "thing" since my last stint in electronics, or did I just miss it?
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AA4PB

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Re: Topology?
« Reply #1 on: September 06, 2021, 10:18:40 AM »

The term probably became popular in describing computer network topology.
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Bob  AA4PB
Garrisonville, VA

N8NK

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Re: Topology?
« Reply #2 on: September 06, 2021, 06:34:34 PM »

Starting in the late 90s, I started designing small superhet Rx, QRP Tx transceivers, including the board layout. I've always called the general placement of the various circuits.. LO, mixers, IF chain, audio section, Tx mixer, Tx RF chain, as the board topology. It's my favorite part of homebrewing.
73 from N8NK
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VK6HP

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Re: Topology?
« Reply #3 on: September 07, 2021, 08:19:23 AM »

"Topology" in a circuit or electrical network is a description of the form of the interconnection of components.  It has nothing to do with e.g. physical layout or component values.  Rather than do a lengthy description here, the Wikipedia article is pretty well written:

https://en.wikipedia.org/wiki/Topology_(electrical_circuits)

I'd have to do some digging to see when the term was first used but I'd guess it's been around a very long time indeed, given the relation between network topology and graph theory.  In the late 1970s when I completed my first degree it was a core part of the engineering network analysis and synthesis topics, as were the associated signal flow graphs.

73, Peter.
« Last Edit: September 07, 2021, 08:31:40 AM by VK6HP »
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W2EAF

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Re: Topology?
« Reply #4 on: September 07, 2021, 11:19:54 AM »

My Bad! I misspoke when I used the term "layout". Poor choice of words. I was indeed referring to the interconnection of components being described as topology and not the physical layout. It's just that by the mid to late 70's I had never come across the term, and least in Ham and hobbyist publications. Until then, the only use of the word I was familiar with was in relation to mathematics and later in computer networking. When picking up on electronics 20 years later it seemed the term had become ubiquitous.

Rob W2EAF
« Last Edit: September 07, 2021, 11:22:24 AM by W2EAF »
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JAHAM2BE

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Re: Topology?
« Reply #5 on: September 08, 2021, 05:38:15 AM »

The term "circuit topology" seems to have been in use in the 1950s, as seen in the below excerpt from the 1952 "Proceedings of the I.R.E.":


The term was also used in magazines of that period, like the 1965 "Electronics" magazine:

W2EAF

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Re: Topology?
« Reply #6 on: September 08, 2021, 06:10:33 AM »

I guess I must have missed it:D I wasn't reading high level technical journals, but certainly read magazines like Electronics. Really surprised I had never heard of it, at least not in construction articles. Ok, anyone know about the use of designations like 4U7 for 4.7uF and 4k7 for 4.7k? Part values weren't called out like that in QST, CQ.73, Popular electronics, etc. back in the day and still aren't today  as far as I know (for example in the August 2021 QST article "Adaptable AGC Circuit")

Rob W2EAF
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VK6HP

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Re: Topology?
« Reply #7 on: September 08, 2021, 07:24:16 AM »

RKM code, used in professional drafting since at least the 1950s:

https://en.wikipedia.org/wiki/RKM_code

In practice I have noticed it more in non-US publications, since at least the 1970s when I started reading hobby magazines.  I always use it in my own schematics, mainly because of the potential lack of clarity around the decimal separator.
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W2EAF

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Re: Topology?
« Reply #8 on: September 08, 2021, 10:22:13 AM »

RKM code, used in professional drafting since at least the 1950s:

https://en.wikipedia.org/wiki/RKM_code

In practice I have noticed it more in non-US publications, since at least the 1970s when I started reading hobby magazines.  I always use it in my own schematics, mainly because of the potential lack of clarity around the decimal separator.

Yes, that book where I first saw it was published in Canada

Rob
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