New expression of values - Page 1
Forum section: electronics / beginners

author: tkamiya
author_rank: Super Contributor
timestamp: July 12, 2020, 04:13:13 am
content: This is a very basic question about expression of numbers and values. When I was seriously into electronics last time, 30+ years ago, convention was different. I'd like to learn more about this.We used to call1.2V to say 1.2 volts3.8A to say 3.8 amps8.8Kohm to mean 8800 ohm.Now I see 1v2, 3a3, and 8K8 ohm.When did this convention start? I'm pretty sure this is to eliminate . and , which are not international (there are dozen more of these decimal separators around the world), and easy to misinterpret. What are these expressions called?

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2020, 04:20:54 am
content: There is real convention (one of them) abot resistors, capacitors and inductors (and how to show their value onto the schematics in a shortest possible way). So 3k3 is ok (and it was so 30 years ago to). Aplly the same way to voltages and currents is out of that convention but is understandable too (we use unit as decimal point).

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2020, 04:25:05 am
content: I apologyse but my grammar nazi wants to add that it is right to write 'kOhm' but not 'Kohm' (because there isn't a 'K' and an 'ohm').

author: tkamiya
author_rank: Super Contributor
timestamp: July 12, 2020, 04:31:31 am
content: Would that be Kelvin Ohm?It doesn't apply to resistance but I was taught to primary use lower case letters to indicate AC value and upper case letter to indicate DC value. (Applicable to voltage and Current mostly)

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2020, 04:36:57 am
content: Quote from: tkamiya link=topic=246852.msg3132596#msg3132596- this is strange and wrong. The grammar has quite strong rules and it doesn't have a rule about AC and DC.

author: tkamiya
author_rank: Super Contributor
timestamp: July 12, 2020, 04:41:23 am
content: You can invent a time machine, learn Japanese, and go tell my high school teacher.... Also, different countries used to use different conventions back then. That was 30+ years ago.

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2020, 04:42:51 am
content: We used a large 'K' with resistors may be to it was better seen for people with poor eyesight (schematics were often reprinted/copied several times). It is a reasonable exception to the rules.

author: greenpossum
author_rank: Frequent Contributor
timestamp: July 12, 2020, 04:48:04 am
content: Quote from: tkamiya on July 12, 2020, 04:13:13 amHaven't seen many 1V2 or 3A3 (are you making them up?) but 8k2 has been in use for a long time because there is no chance of missing the decimal point in schematics because the paper is worn out or your eyesight is not great.

author: bdunham7
author_rank: Super Contributor
timestamp: July 12, 2020, 04:52:30 am
content: Forcomponentslike resistors 5R6 = 5.6 ohms, 4K7 = 4700 ohms, 1M5 = 1.5 million ohms, etc.3V3 would refer to a 3.3 volt regulator or zener. You wouldn't say that you measured 3V3 or to set a trimpot to 3V3. At least as far as I know. I'm not sure if there is a standard someplace that specifies all the details.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 12, 2020, 06:50:42 am
content: Things like "3V3" are handy in netnames during design phase. Dots innamesare confusing, and short names are better, even saving 1 character is good.3A8 would be very odd, never seen it.

author: John B
author_rank: Frequent Contributor
timestamp: July 12, 2020, 06:54:42 am
content: Quote from: Vovk_Z on July 12, 2020, 04:36:57 amI've seen lower case for AC and upper case for DC, especially in amplifier analysis.

author: newbrain
author_rank: Super Contributor
timestamp: July 12, 2020, 08:33:30 am
content: Quote from: Vovk_Z on July 12, 2020, 04:25:05 amI apologyse but my grammar nazi wants to add that it is wrong to write 'kOhm' but not 'kohm' (because there isn't an 'Ohm').And, in fact, it should be kiloohm.

author: Circlotron
author_rank: Super Contributor
timestamp: July 12, 2020, 08:41:43 am
content: Quote from: Vovk_Z on July 12, 2020, 04:25:05 amI'd go for Ohm because it is a surname, like Volt and Ampere and several others.

author: newbrain
author_rank: Super Contributor
timestamp: July 12, 2020, 08:51:42 am
content: Quote from: Circlotron on July 12, 2020, 08:41:43 amBut you'd be wrong, unless you want to make your own units.SI system uses capitals for unit symbols derived by names (V, A, W, Pa), bur when spelled in the long form they must be lower case, unless, of course, at the beginning of a sentence.

author: Zero999
author_rank: Super Contributor
timestamp: July 12, 2020, 08:56:05 am
content: Quote from: Vovk_Z on July 12, 2020, 04:42:51 amStrictly speaking, it should be a lower case k, as the capital K is for Kelvin, but it's pretty obvious it's a resistance, when the number is next to a resistor.

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 12, 2020, 09:26:36 am
content: Quote from: newbrain on July 12, 2020, 08:51:42 am- oh, you are right! (Shame to me. I was hoping on short winning grammar war - but it wasn't)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 12, 2020, 10:19:47 am
content: Quote from: tkamiya on July 12, 2020, 04:13:13 amBritish standard. "We" didn't start using it (I see your US country flag?), it's been around for a long time and probably it's just leaking in among amateur groups which find whatever English language resources they find -- US or UK.Megacycles and whatnot are definitely long since passed though..Tim

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2020, 06:22:37 pm
content: SI units are SI units, nothing much to discuss there, full consensus exists; both for unit abbreviations and multipliers.Full information on SI is abundant on the web, you'd be well-advised to stick to it.That there are people around who insist on inventing their own units, eg, KWatt (KelvinWatt??), Kohm (Kelvinohm??), MA (MegaAmpere??) etc., well, that's just the way of the world.The other issue with 3V3 or 4k7 or 2n2 is different. It's steno in netlists (who mostly don't like . or , or <space> in a name), for schematics where space is often restrained, and for manufacturers who use it in part numbers.The third area is symbolic notation as used in equations.For instance R, C, L for resistance, capacitance, inductance; U and I for DC voltage and current, u and i for AC ditto and so on. In English publications, V and v are often used for voltage, ROW tries to avoid this due to possible confusion between unit and symbol.The only thing really open to discussion is actually: should you write 5V or 5 V? No consensus here

author: TimFox
author_rank: Super Contributor
timestamp: July 12, 2020, 06:51:48 pm
content: Personally, I prefer "5 V" to "5V" in text, since I would write "5 volts" when not abbreviating, but I could not find a definitive answer to that question (not even in the Chicago Manual of Style).To eliminate the confusion between "." and "," for decimal point and thousands, the AIP recommends a space (without character) for thousands (but with a decimal point on-line), but others use a vertically-centered dot for the decimal point. English-language publications try not to use the "," for decimal point, and now avoid it for thousands. I always liked hearing the Olympic judges read out "null comma sechs".I have seen absurdity when people can't bother distinguishing "m" for milli from "M" for mega. I once saw a relay where thecontactresistance was "10 Mohm", but theinsulationresistance was "100 mohm": that would be a useful switch!To avoid confusion between the variable "V" for voltage and the unit "V" for volts, careful usage will italicize the variable (as an algebraic term). Recently, I have found expensive books from reputable technical publishers that can't bother to italicize the terms in their equations. Even $200 books from Springer Verlag.

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2020, 07:10:26 pm
content: Quote from: TimFox on July 12, 2020, 06:51:48 pmYes, that's a workaround. But nothing more. Leafing through my (US/English) textbooks do not indicate that it's normal practice to italicize symbolic terms. Much easier to just use U/u, but you're stuck with V/v, I guess. ROW has no problems.

author: TimFox
author_rank: Super Contributor
timestamp: July 12, 2020, 08:14:50 pm
content: My reference is the Chicago Manual of Style, for English-language publishing. Chapter13 of the 12th edition states that mathematical terms are set in italic type, but abbreviations (e.g., “log”, units of measurement, and chemical elements) are set in Roman type. “Although it is rather uncommon, a mathematics book may require the use of some letters in Roman, usually to indicate properties different from those expressed by the same letters in italic.” Chapter 13 (Mathematics in Type) starts by referring to it as “difficult,orpenalty, copy.”My Physics textbooks follow this direction.Specifically, it is very common to have the variableVand the unit V in the same equation, where lower-case v is not appropriate. The equation editor in Microsoft Word defaults to italic, and you need to select “text” to get a non-italic letter, as in the previous sentence.A Canadian reference that specifies these rules succinctly ishttps://gradstudents.carleton.ca/2014/use-mathematical-equations-thesis/Here is the statement from NIST:https://physics.nist.gov/cuu/pdf/typefaces.pdf

author: WattsThat
author_rank: Frequent Contributor
timestamp: July 12, 2020, 08:27:16 pm
content: QuoteIt is common use in the variable speed drive industry. The A is the decimal in the amp rating, all encoded in the part number along with enclosure class and voltage rating, depending upon manufacturer.

author: TimFox
author_rank: Super Contributor
timestamp: July 12, 2020, 08:47:45 pm
content: “4R7” is better than jumping through hoops to get a majuscule omega.

author: newbrain
author_rank: Super Contributor
timestamp: July 12, 2020, 09:28:44 pm
content: Quote from: Benta on July 12, 2020, 06:22:37 pmThere might be no consensus, but there is a rule.The space is needed, - I'm guilty of forgetting it more often than not, though - as stated by 5.3.3here, a brochure from the primary source: Bureau International des Poids et Mesures (BIPM):QuoteUse of space as a multiplication is extremely important when the unit might be ambiguous: a speed can be expressed inm s-1, a decay rate inms-1

author: John B
author_rank: Frequent Contributor
timestamp: July 12, 2020, 09:44:07 pm
content: Can we all agree that mF is actually a millifarad and that old caps are labelled incorrectly?

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2020, 09:58:19 pm
content: @newbrain:Very interesting. I've always used space between value and unit (it just felt right), but that there's a recommendation is new to me. Thanks for the hintI love precise communication on technical issues (call me "unit nazi"), it eliminates unnecessary discussions and ensures that everyone is speaking about the same thing in the same language.

author: TimFox
author_rank: Super Contributor
timestamp: July 12, 2020, 09:59:43 pm
content: I am old enough to remember "mmf" (pronounced "micky-mikes") for what modern man would call "pF". I also remember when "nF" became popular. Occasionally, one will see "M" sneak into otherwise civilized discussion from accounting sources, meaning one thousand "k". Most authorities permit "uF" for microfarad, to avoid Greek letters. Of course, "F" for "farad" is always capitalized, as in "fF" for femtofarad.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 12, 2020, 10:12:49 pm
content: All of this style interpretation is strange among geeks. You would think this is a forum for writers and editors.Per the OP's question I don't think there is a general move to this notation for standardization reasons, but it is creeping in, and for what I believe are the following reasons.1. As components got smaller and went away from tubular shapes the color banding system of marking got less and less practical. Color banding may also have fallen victim to equal rights petitions from color blind folk. Using an exponent character separating two digits allowed marking component value with a minimum number of characters. (Unfortunately as components continued to shrink the practicality of marking components by any method is going away).2. It then tracked to schematics as a convenience to have documentation match the hardware.3. It is now spreading because of familiarity.But in my particular circles it is common for component values including zener diodes, but relatively uncommon for voltages and currents.As long as enough Rosetta Stones are left around so that old documentation can be interpreted by people immersed in the present change like this is good. It solves a problem.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 13, 2020, 01:39:44 am
content: Spacing is part of the standard, too!https://physics.nist.gov/cuu/Units/checklist.htmlNot precisely from the source, but NIST of course adopts SI in whole so this is adequate.Heh, hmm, the page is only 2004 -- I don't think much if anything has changed in formatting in that time but you may want to check it from the source anyway..Anyway, down by #15 is what we're looking for.Quote from: CatalinaWOW on July 12, 2020, 10:12:49 pmGeeks do have to write, from time to time. Sometimes grudgingly. Many of us are aware of the shortcut -- in LaTeX, just toss it through siunitx, all the formatting has already been done for us by other geeks.Tim

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 13, 2020, 12:44:05 pm
content: I was always told that the reason for writing 4k7 instead of 4.7 kohm (forgive me for not bothering to find the ohm symbol, which is actually a different character than omega: "U+03A9: Greek Capital Letter Omega" vs "U+2126: Ohm Sign") was for printing reasons. I was told only to ever do this on schematics, and there is was actually supposed to be 'good' practice, because after photocopying or low resolution prints on a background that might have a grid and so on, the dot between the 4 and 7 could be hard to spot, and it could be mistaken for 47 kilo ohm instead. By writing 4k7 you avoid this from happening.Regarding spaces between unit and number: I do try and use siunitx when using latex, though I try to avoid latex as much as possible. Another big advantage of siunitx is that it (should) prevent the typesetter from breaking up the number from the unit, so you never get'blahblah blah was 5V and alallalala is 2.3m. Therefore, ...'I try to avoid using italic, as usually italic is used for mathematical operations, and I want to avoid any confusion between mathematical variables and units (especially since standard practice is to use capital 'V' for variables denoting voltage, which could easily be confused with the unit being represented by V). My absolute preference is to use a math-font separate from the general font, but from the same family of fonts, and within that 'math font', use standard letters for variables, and in this case italics for units.

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 13, 2020, 04:47:00 pm
content: mF is definitely millifarad.

author: Benta
author_rank: Super Contributor
timestamp: July 13, 2020, 05:49:27 pm
content: Quote from: TheUnnamedNewbie on July 13, 2020, 12:44:05 pmThis is only true for the US (I'm not sure about UK/Commonwealth). ROW uses U or u for voltage variables.

author: Benta
author_rank: Super Contributor
timestamp: July 13, 2020, 05:53:56 pm
content: Quote from: Vovk_Z on July 13, 2020, 04:47:00 pmYes, in the SI worldBut earlier it was very common in the US to use mF for microfarads. This practice ended in the 1980/90s, but try opening an old radio or TV, you'll see what I mean. The electrolytic caps are definitely not millifarads, but marked with mF.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 13, 2020, 06:22:34 pm
content: Recently I was criticized for a post I made where I used uF instead of mu, or Alt+0181, for µF. It wasn’t that my use of uF was misunderstood or even incorrect, it was just a case of OCD (or is it COD ) run amuck.Apparently no one here remembers that the letter ‘k’ or ‘K’ used with ohms is also a newer convention that I had to get used to because all the old books I had dating from around WWII used ‘M’, like the roman numeral ‘M’, for a 1000 multiplier with ohms, and megohm for 1,000,000 ohms.The schematic below should make it clear. Oh, except for the capacitor values in ‘puff’ or MMF and the inductor value in MH. Oh, and the funny stuff inside the circles are symbols for thermionic valves or tubes.

author: dbctronic
author_rank: Regular Contributor
timestamp: July 13, 2020, 07:10:00 pm
content: Quote from: ArthurDent on July 13, 2020, 06:22:34 pmFunny stuff? Was ist das 'funny stuff'? You got some other kind of electronic devices?The 5U4GB is and always will be the foundation of my designs!Those old tube radio electrolytics got away with using 'mF' for microfarads because in those days there were darned few capacitors over 1 millifarad inanykind of equipment. The dual 40/80 uF in power supplies ruled the waves.Caps are the biggest pain when it comes to units because they span the largest range of magnitudes. Right now, Digikey sells caps from 0.1 pF to at least 6000 F, a range of 6x1016to 1.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 13, 2020, 07:27:31 pm
content: ..."Digikey sells caps from 0.1 pF"...What you get if you order these is an empty bag.Do you remember what a 'gimmick' is?https://en.wikipedia.org/wiki/Gimmick_capacitor

author: tkamiya
author_rank: Super Contributor
timestamp: July 14, 2020, 07:20:14 am
content: I'd add, accepted common prefix is highly dependent on country. In Japan, we use milli, micro, and pico but never nano in component values. It's technically correct, but just never used. So as deca. It's almost never used anywhere. In US, nano is in common use especially in capacitance. Hence my confusion. My training spans two countries. It also spans 40+ years with interruption in the middle.Grammar policing is not something I'm interested in, so you guys carry on. Thanks to all who contributed to my better understanding on conventions, thank you.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 14, 2020, 07:28:28 am
content: Quote from: Benta on July 13, 2020, 05:49:27 pmI'm not from the US, nor was I educated there. I was under the impression it was more of a micro-electronics-vs-power-electrical-systems. My coursebooks on motor drives and power distribution and so on all use U for voltage variables. In my electronics courses and in my work (microelectronics EU) I've never ever seen someone use U for voltage (sometimes I see it used for EMF though).Quote from: tkamiya on July 14, 2020, 07:20:14 amI've seen the habit of avoiding nano in practice too when buying capacitors. Farnell lists capacitors in 10000 pF instead of 10 nF, which I just find frustrating since it's easy to confuse (or at least for me) 100000 pF with 10000 pF when you have a wall of values in front of you.deca is a bit different I think, since it is not a preferred multiple-of-three.

author: oosmile
author_rank: Newbie
timestamp: July 14, 2020, 07:35:56 am
content: i want learn from texaspyro~

author: TimFox
author_rank: Super Contributor
timestamp: July 14, 2020, 01:46:42 pm
content: Quote from: ArthurDent on July 13, 2020, 07:27:31 pmYears ago, we needed 0.5 pF C0G chip capacitors. The manufacturer’s stated tolerance was +/- 0.5 pF.

author: dbctronic
author_rank: Regular Contributor
timestamp: July 14, 2020, 06:35:11 pm
content: 0.5 +/- 0.5? That's almost an April Fool's joke! Hopefully, they are priced to account for the fact that 20% of them are ArthurDentian phantom components.I guess that a 0.1 pF cap must be two leads stuck into a blob of insulator material (through hole type) or a ceramic block with two end contacts (SMD type).That gimmick capacitor must have a horribly low self resonant frequency, innit? OK for fine trimming feedback in audio amps, maybe...

author: Benta
author_rank: Super Contributor
timestamp: July 14, 2020, 07:18:05 pm
content: Quote from: TheUnnamedNewbie on July 14, 2020, 07:28:28 amYes, your impression is right, but that's because the microelectronic/semiconductor industry started in the US, and most datasheets etc. come from there. But if you look at Siemens, Infineon, ST, etc. (European datasheets), U and u are widely used.

author: wizard69
author_rank: Super Contributor
timestamp: July 14, 2020, 07:20:35 pm
content: Quote from: tkamiya on July 12, 2020, 04:13:13 amThey are called a mistake as far as I'm concerned. I never liked this approach.Now back in the old days there was a huge problem with engineering drawings in that characters like ".", "," and others would get lost in the reproduction process. I'm not sure if this was a factor in the adoption of these expressions or not. Personally I find them to be an ignorant way to express a value on a print.

author: wizard69
author_rank: Super Contributor
timestamp: July 14, 2020, 07:24:19 pm
content: Quote from: Siwastaja on July 12, 2020, 06:50:42 amShort names are not good!!!! Anybody exposed to the early days of BASIC on microprocessors can attest to that. Today we have C++ to prove that point once again.

author: cliffyk
author_rank: Frequent Contributor
timestamp: July 14, 2020, 07:55:58 pm
content: This has been my bible in all things metric since I bought it for school (good god, that was 50 years ago):Abbreviated units are capitalised only when the unit has been derived from a proper name as in K, N, H, Hz, V, A, W (Kelvin, Newton, Henry, Hertz, Volt, Ampere, Watt). Numerical prefixes and symbols are not capitalised except for T, G, M (tera, giga, mega) to prevent confusion with non-proper unit names. Unabbreviated units are not capitalised (e.g. kelvin, newton, hertz).This guidance is profoundly and routinely ignored by advertisers, an sometimes even engineers. I see the wavelength of our curing lamps often expressed as 405 NM--405 newton megas?Here's one on Amazon for $7.54(I think it's $25 or mre from ASTM).

author: TimFox
author_rank: Super Contributor
timestamp: July 14, 2020, 08:11:25 pm
content: A quick Google search for the abbreviation for voltage (in English-language sources) has "V" as the most popular abbreviation (by far), with "E" for emf a distant runner-up, and "U" almost unheard of. Of course, this was restricted to English-language usage, and usage in other languages may differ.

author: cliffyk
author_rank: Frequent Contributor
timestamp: July 14, 2020, 08:43:50 pm
content: Quote from: wizard69 on July 14, 2020, 07:24:19 pmAnnex B of the C++ standard (July 1, 2009) states that implementations of the language should support 1024 characters as a minimum. Microsoft and Intel C++ both support 2048.What I can't abideALL_CAPS_AND_UNDERSCORES; a convention held over from COBOL and DIBOL in the 70s;MixedCaseLikeThisis my preference.I also generally use a 3-character prefix to indicate the type of what is being identified. E.g. strMyName, fncSaveMyName(), subSaveMyName, objMYName, objMYName.strFirst, intLengthMyName, etc.--saves me a lot of hassle when I have to rework code I wrote 20 years ago...

author: ejeffrey
author_rank: Super Contributor
timestamp: July 14, 2020, 08:59:52 pm
content: Quote from: Circlotron on July 12, 2020, 08:41:43 amThat's certainly not the SI standard or used in any style guide I know of. Volta and Ampere are people. The units named after them are volt and ampere and are only capitalized in situations where common nouns would normally be capitalized, such as in a title or beginning of a sentence or (I think) in German. They *are* capitalized when abbreviated: 1 millivolt = 1 mV whereas units not named after people are not capitalized even when abbreviated: 1 millisecond = 1 ms.

author: Benta
author_rank: Super Contributor
timestamp: July 14, 2020, 09:31:14 pm
content: Quote from: TimFox on July 14, 2020, 08:11:25 pmQED. Stay in the ivory tower, ROW doesn't exist...

author: cliffyk
author_rank: Frequent Contributor
timestamp: July 14, 2020, 09:58:47 pm
content: Quote from: ejeffrey on July 14, 2020, 08:59:52 pm^Yup...

author: TimFox
author_rank: Super Contributor
timestamp: July 14, 2020, 10:27:06 pm
content: Quote from: Benta on July 14, 2020, 09:31:14 pm"Even that Springer Verlag English-language textbook (copyright 2011) that I complained about for non-use of italics uses "V" for voltage, and "e" for noise voltage. Appendix 4 (six pages) of abbreviations and symbols has many "V"s, a few "e"s, and only one lonely "u0" for source signal voltage (which may be a typographical error: I can't find the symbol in the 752-page book).I don't presume to tell others how to write their language.

author: fourfathom
author_rank: Super Contributor
timestamp: July 14, 2020, 10:45:42 pm
content: Quote from: dbctronic on July 14, 2020, 06:35:11 pmI can't give you any self-resonant frequency numbers, but we've used gimmicks in HF and VHF radio tuned circuits. I recall one top-coupled bandpass filter that used a gimmick for inter-stage coupling. We would cut / twist as needed to get the desired bandpass shape.

author: TimFox
author_rank: Super Contributor
timestamp: July 14, 2020, 10:54:58 pm
content: Gimmick capacitors were also common for neutralization circuits in HF and VHF receiver circuits. The inductance of such a short twisted pair can't be much, and the capacitance is small, therefore the self-resonance is high.

author: tkamiya
author_rank: Super Contributor
timestamp: July 15, 2020, 12:35:29 am
content: I've used them too in different varieties. Twisted or just two wires close together. I don't recall self-resonance ever being a problem. At least at 2 meters band, it was a non-issue. (144MHz)

author: Siwastaja
author_rank: Super Contributor
timestamp: July 15, 2020, 11:55:59 am
content: Quote from: wizard69 on July 14, 2020, 07:24:19 pmGood for you!!!! So feel free to call your CPU voltage bus std::VoltageBusFactory(VoltageGenerator::CreateSupply("3.3 Volts")); in your schematic and see how well it works during schematic capture and layout.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 15, 2020, 03:42:48 pm
content: Quote from: TimFox on July 14, 2020, 10:54:58 pmSome years ago I was troubleshooting a piece of test equipment, maybe made by HP, and found something strange. There was a solid wire about 2 inches long going to a terminal strip like the one shown below. The wire was soldered to the single insulated lug on the strip but there was nothing else connected. I checked the schematic and it showed a capacitor connected to that point but there was none there so I was wondering how this device had worked for years with a missing capacitor.What I found after further investigation and checking the parts list was that the capacitor value was very low. The designers determined that a capacitor was needed but the value needed was so low that just the 2 inch wire soldered to the terminal strip was just the value need for the circuit to work the way it was intended. This wasn't an r.f. unit so I didn't expect something like this. The wire/terminal strip was kind of like a gimmick but looked more professional.

author: Zero999
author_rank: Super Contributor
timestamp: August 17, 2020, 09:33:25 am
content: Quote from: John B on July 12, 2020, 06:54:42 amThe convention is upper case for steady state values, such as DC or the RMS value of an AC waveform and lower case for instantanious values.Quotehttps://www.ee.iitb.ac.in/~spilab/Tips/IEEE_letter_symbols_1964.pdf