The reason for specific passive component values

[Winston]

Didn't know this, never even wondered about it even though I should have considering the seemingly weird values.

E series of preferred numbers

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

The E series is a system of preferred numbers (also called preferred values) derived for use in electronic components. It consists of the E3, E6, E12, E24, E48, E96 and E192 series, where the number after the 'E' designates the quantity of value "steps" in each series. Although it is theoretically possible to produce components of any value, in practice the need for inventory simplification has led the industry to settle on the E series for resistors, capacitors, inductors, and zener diodes. Other types of electrical components are either specified by the Renard series (for example fuses) or are defined in relevant product standards (for example IEC 60228 for wires).

This is what made me aware of this:

 

[OverTheTop]

Geometric series

I so hate E96 resistor values.

 

[SteveThatcher]

I have been designing electronic devices from grade school on for the last 50+ years. I never took the time to find out why the values were what they were - I just accepted them. The internet certainly makes it easier to find out why, but I guess I had moved beyond even thinking about the "history and reason for values". Now that this has been pointed out, I will think about the posts here and be amused every time I design something from now on.

 

[jlabrasca]

I think asked this question when I got my first Heathkit or Radio Shack kit, but I have to admit that I did not bother to research the answer until prepping to teach a circuits class for the first time.

FWIW, I make preferred number series part of the the lecture when I teach error analysis and propagation of uncertainty.

 

[SteveThatcher]

I think asked this question when I got my first Heathkit or Radio Shack kit, but I have to admit that I did not bother to research the answer until prepping to teach a circuits class for the first time.

FWIW, I make preferred number series part of the the lecture when I teach error analysis and propagation of uncertainty.

I do the same sort of thing. You can usually work with a given list of values and not compromise your design. I put my share of Heathkits together also. My favorite "go to" part back when I was in grade school (60s) were telephone company stepping relays they used for routing calls before semiconductors devices. I scored a bunch of them from a garbage can behind the telco building... I built a few different things that needed to sequence lights. Fond memories...

 

[Winston]

I do the same sort of thing. You can usually work with a given list of values and not compromise your design. I put my share of Heathkits together also.

I built the kit for this fantastic Heathkit course on microprocessors, the course using my favorite architecture then (and forever, actually), the 68xx series, with the excellent course materials in multiple 3-ring binders. I built it as much as possible to NASA/milspec soldering standards because I was in the USAF at the time and had just attended a course on that. I sold it after completing the course and additional experimentation for what I paid for the kit. Many are on eBay because schools used them, but the course materials are nearly always missing:

 

[jlabrasca]

My first computer was a Heathkit. Or it it might have been the Radio Shack Science Fair version.


I didn't realize it was so expensive. $25 was a lot of money in 1975. I was a spoiled kid.

The Heathkit catalog was great reading.

 

[Winston]

My first computer was a Heathkit. Or it it might have been the Radio Shack Science Fair version.

View attachment 359006
I didn't realize it was so expensive. $25 was a lot of money in 1975. I was a spoiled kid.

The Heathkit catalog was great reading.

The ET-3400A was my first. I really wish I'd saved it and every other computer I owned up until I converted over exclusively to homebuilt x86 systems. BTW, I can't recommend the ET-3400A enough, even today, as a great course if you REALLY want to know how microprocessors work as long as you can get all of the course materials. It's been too long for me to be sure that they're all shown in this photo:

 

[Tobor]

The Heathkit company resurfaced a few years ago and started producing kits again (Link). If anyone is seriously interested in their Micro course, I would suggest contacting them (Link).

 

[OverTheTop]

I built their digital multimeter kit that had Nixie tubes for the display!

 

[SteveThatcher]

let's see... frequency counter with nixie tubes, multimeter with nixie tubes, 25" console TV, Shortwave receiver, vacuum tube voltmeter, H19 ASCII terminal, high voltage power supply, RF Signal generator, tube tester, and probably others that I can't remember...

 

[OverTheTop]

let's see... frequency counter with nixie tubes, multimeter with nixie tubes, 25" console TV, Shortwave receiver, vacuum tube voltmeter, H19 ASCII terminal, high voltage power supply, RF Signal generator, tube tester, and probably others that I can't remember...

Heathkit Fan Club president?

 

[jlabrasca]

I built their digital multimeter kit that had Nixie tubes for the display!

I don't think I ever saw that one.

Looking at the old catalogs I am struck by the variety of product offerings.

Growing up, one of our neighbors was a "tinkerer" or an "electronics buff" -- as we called them in those days. He had a Heathkit stereo (quadraphonic?) amplifier with a built-in oscilloscope.

He gave my family a VHF radio kit one Christmas. Which kit he then repaired and completed for us when my brother and I tried to use a wood burning pen as a soldering iron.

Those were the days. A middle-aged bachelor could lure young boys into his garage with a spool of solder and a promise of being able to listen-in on police radio calls, and their parents would thank him for it with a bottle of Canadian Mist. <g>

The Heathkit company resurfaced a few years ago and started producing kits again (Link). If anyone is seriously interested in their Micro course, I would suggest contacting them (Link).

Yeah, I looked at the Explorer radio when it was announced. I will be interested when they bring back the color-organs -- or that oscilloscope-equipped receiver.

 

[SteveThatcher]

Heathkit Fan Club president?

funny... In high school, I put together kits for the electronics class. I also did a few for friends and then there was my own stuff I worked on. I think the TV was the last thing I put together and that was late 70s. Didn't know they had a club... LOL

 

[cerving]

This was my first computer... I think I was in 4th grade.

 

[Steve Shannon]

This was my first computer... I think I was in 4th grade.

I had that same one, but I wasn’t quite the prodigy you were. I was a little older, I think, maybe 6th or 7th grade.

 

[jlabrasca]

This was my first computer... I think I was in 4th grade.

Are you using it now to upload images to TRF? (imagine that I ended that sentence with whichever smiley indicates good-natured kidding. I cannot see the images you uploaded)

I googled the file name. Apparently you can buy reproduction kits.

https://www.mindsontoys.com/kits.htm?dc1_order.htm

$60 is too dear for me, and cloning it seems like it would be a lot of work for something that would only decorate my desk.

This thing. OTOH

https://shop.evilmadscientist.com/tinykitlist/375-dcii

looks like it might be an interesting CNC project and it would look cool hanging on a wall.

Thanks, by the way, for reference. I did not know this device existed. It seems quite wonderful to me.

Sort of on topic, I am often reminded by how my understanding of the relationship between measurement and computation differs from my students' understanding of this relationship. I am just old enough to have learned how to operate a slide rule, and I learned drafting (and draftsmanship) in room next to a machine shop and free of any electronics more complicated than an HP-11C.



edit: not enough coffee in the world