HT Smoothing Condensers

[Mark Hennessy]

It's an interesting question. Last time I searched, I stumbled across this discussion: http://electronics.stackexchange.com/questions/222137/why-was-a-capacitor-called-a-condensor-condenser-in-the-early-days-of-electro - where it is suggested that the electricity => water analogy was behind it. Condensing involves latent heat.

I agree about nano. I don't remember the days when it wasn't in common use in electronics, and have never come across a historical explanation for the apparent opposition to it, but am glad that I didn't have to navigate those waters...

[Nowhere-Man]

Thanks Mark. This isn't an extended visit and I don't use internet forums these days. Neither do I wish to "rock the boat", as it were. On the topic of terminology I recently was obliged to defend Rick Mcwhorter over his expression of positive grid bias. To me it seemed clear he meant "less negative" or "veering to positive" but there was an uproar on forums. At any rate this is my last post for a while but I am working on the website which is pretty demanding. If it was miguel lopez referred to I recall he works on USSR stuff and I hope to be selling Soviet radios too. Now I have a bit of work to do on that German set with the schematic but maybe chill out later. Cheers

[Valvebloke]

... I agree about nano. I don't remember the days when it wasn't in common use in electronics, and have never come across a historical explanation for the apparent opposition to it, but am glad that I didn't have to navigate those waters...

I do too. I spent some time making nanosecond (and subsequently picosecond and femtosecond) pulses for a living and one of the primer books in the field was Millimicrosecond Pulse Techniques by Lewis and Wells. This even sounded strange back in 1980. Perhaps one reason for that was the fact, well-known amongst those of us who actually had to work with physical kit, that the speed of light in vacuum is pretty accurately (within a couple of percent) one foot per nanosecond, indicating that, like the foot, the nanosecond is a 'natural' unit   .

VB

[ppppenguin]

Physicists have used "sceintific" notation for many decades. Certainly in written work, less so in speech. For example 2.7*10^-9 would be 2.7 nano (the ^ is a fairly modern convention from computer programming, traditionally the exponent was a superscript) This notation saves lots of zeros which can be confusing to anyone. Even those who are very numerate can boggle at counting up all those zeros. Another modern way of writing this is 2.7E-9. This is typically how you would enter it into a calculator.

The engineers took this one step further and used exponents that multiples of 3. This fits with pico, nano etc.

In the days before calculators people used slide rules and log tables. This only helped with the significant digits. You did the exponent manually. It gave you a very good sense of the order of magnitude of the result.

[Terry]

This notation saves lots of zeros which can be confusing to anyone. Even those who are very numerate can boggle at counting up all those zeros.

Ah yes - all those formulae where L is in Henries, C is in Farads and F is in Hertz!

You can have a lot of fun (not!) with all those zeroes!

[Valvebloke]

Physicists have used "sceintific" notation for many decades ...

Except for some of the more 'conceptual' of the theorists who simply set as many of the fundamental constants as they can get away with (speed of light, charge on the electron, Planck's constant, permittivity and permeability of free space etc, etc) to one https://en.wikipedia.org/wiki/Natural_units. Working out how their 'results' relate to anything in the real world can be a nightmare.

VB

[Nowhere-Man]

Yes, I can see how this has caused confusion. I am on an actual PC now so can paste μF. I was the mF I used that was confusing. I now have constant internet on a small Blackberry mobile but I can't copy and paste on it and so typed microfarad as mF (which I confess is misleading). It would have been better to type:

Microfarad.
Micromicrofarad.
Picofarad.
Nanofarad.

This may help:

If there are a million picofarads in one microfarad, start by 0.5 μF as 500,000 picofarads. Except, sure, nobody uses such a figure but it helps me work down to 0.0005 μF (which you do find in RF capacitor (grid coupling and so forth.)

I used to derive nanofarads from an initial picofarad value but maybe that was a bit long-winded., so now I just think of 0.01 (10 nanofarads).

I'm sorry when I use the Blackberry I can't use the symbols. However, it seems wise to type the whole words.

[ppppenguin]

If you can't use the μ symbol the convention is to use u (lower case of U). This is unambiguous. Hence 0.47uF, 4.7uF etc.

Modern usage would commonly say 470n for 0.47uF and 4u7 of 4.7uF.

[Nowhere-Man]

Well, yes, I do stand corrected for my former error. Any possibility of being understood as using millifarads was not what I intended.

I did use to have these mental blocks at Maplins some months ago when trying to locate capacitors. The staff were not much use at all, except for one guy who wasn't too bad. I recall him saying, "Well, we only have 100 nanofarads", and I'd just block because I was used to old texts and micromicrofarads. So in one case we had to google a converter.

On another theme I did solve the mystery of the low volts on a EABC80 anode. I'd been mystified to get only 60 odd volts on the anode and assumed there was an HT issue. Finally I located the workshop readings for the whole set voltages which I'd not noticed tucked away. It's meant to be 60 odd volts. Apparently Philips and some German radios do use lower voltage valves sometimes. I have more data on this valve but not time now to post details.

[Mike Watterson]

On Linux, AltGr m gives µ, but on windows (and often Linux out of habit) I only put u unless I'm doing a proper document, then I use Windows Charmap accessory, that is on my task bar.

I've never understood why UK Windows only as áéíóú €ÁÉÍÓÚ as AltGr. The default Linux UK Keyboard map has two extra AltGr (or Apple symbol key) on every typing key, that's 2 x 48 easy to type characters before invoking "Compose" key (mapped to Caps Lock). I do have to use the Linux Charmap tool (like Windows) for the full Greek and Cyrillic alphabets. The Altgr does cover Icelandic/Scandinavian, German, French, Spanish, Polish and Turkish (all accents via dead keys), but not the old Insular Gaelic/Irish characters (used in modern Cornish).