Milli Farad or Micro Farad. - Page 1
Forum section: electronics / beginners

author: solder_boy132
author_rank: Contributor
timestamp: January 27, 2021, 05:51:12 am
content: So i put in a new CRT in my scope, works well except that when i turn it on i smell capacitor guts and electrolyte. So im new to repair and all that stuff, but the question is, is this capacitor Milli Farad or micro Farad. My Multi Meter wont ready any thing because they are all dead from the big fall some how. The Mallory says 840MF 12v but the Jamicon says 2200uf 16v. The Jamicon is smaller and higher rated than the Mallory so the Mallory may be 840 milli farad, but its from 1980s era so idk.

author: solder_boy132
author_rank: Contributor
timestamp: January 27, 2021, 05:51:59 am
content: Quite the storm here in Sacramento right now.

author: fourfathom
author_rank: Super Contributor
timestamp: January 27, 2021, 06:05:01 am
content: "MF" on old electrolytic capacitors = uF = microfarads.Finally getting some rain (and wind) here near Bodega Bay. Power keeps coming and going. Glad we've got a diesel auto-switch generator and UPS.

author: bob91343
author_rank: Super Contributor
timestamp: January 27, 2021, 07:15:30 am
content: Until the advent of super capacitors, there were no capacitors available in convenient sizes that were anywhere near 1 Farad. So the M incorrectly means micro. Millifarad is a relatively new word that unfortunately starts with the same letter as microfarad.So 1 F = 1000 mF = 1,000,000 uF = 1,000,000,000 nF and so on through pF and fF.

author: ledtester
author_rank: Super Contributor
timestamp: January 27, 2021, 07:26:33 am
content: Not having use of your multimeters, to distinguish milli- from micro- farads you could set up this circuit:The time for the LED to turn on will be roughly R*C/V where V is measured in volts. For V=5V, R = 10K and C = 840uF this comes to a couple of seconds. If the cap is milli-farads the time will be 1000 times longer.

author: gnuarm
author_rank: Super Contributor
timestamp: January 27, 2021, 12:48:27 pm
content: Quote from: bob91343 on January 27, 2021, 07:15:30 amIt may or may not frighten you to know that the medical and pharmaceutical industry eschews the use of the greek µ (mu) symbol or even the 'u' character for micro. They use "mc" for micro and "m" for milli. One of the reasons for "250,000 deaths per year are due to medical error in the U.S."

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 30, 2021, 09:06:46 pm
content: Quote from: gnuarm on January 27, 2021, 12:48:27 pmIn Russia, the designation mk (in the Russian alphabet) is accepted, which means mc. In the diagrams, it is customary to indicate the capacity in microfarads with the letters mkF, and to indicate the other capacity in picofarads and not to indicate the letters. Similarly, a resistor whose resistance is indicated in Ohms is not indicated by letters.

author: TimFox
author_rank: Super Contributor
timestamp: January 30, 2021, 10:03:59 pm
content: Even more frightening is the use (in accounting, etc.) of majuscule M to indicate 1,000 (from the Roman numeral M) but not 1,000,000 (mega). I have a pre-war Simpson meter that uses M for 1,000 ohms instead of k.I often find modern misuse of m and M by careless people. I remember a relay with an insulation spec of 100 mand a contact resistance of 20 M, and said to myself “What a useless switch!”.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 30, 2021, 10:36:00 pm
content: When we have someone who does not mean something as usual and is asked, he answers "so that the enemies do not guess".

author: TimFox
author_rank: Super Contributor
timestamp: January 30, 2021, 11:10:17 pm
content: By the way, here is the US NIST list of standard prefixes for metric units:https://www.nist.gov/pml/weights-and-measures/metric-si-prefixesfrom "yotta" Y (10+24) down to "yocto" y (10-24)Unfortunately, some of the prefixes for greater than unity (k, h, and da) are minuscules, while all prefixes less than unity are minuscules. From M up, the other greater-than-unity prefixes are majuscules. I was surprised to see that their preferred pronunciation for "giga" uses a soft initial "g" and a hard final "g", but that follows the rule for romance languages for g before i and a.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 30, 2021, 11:23:18 pm
content: Quote from: TimFox on January 30, 2021, 11:10:17 pmThis is the international SI system, isn't it? In Russia, such prefixes have always been used if the designation was written in latin.Russian letters are exactly the same, except for micro = мк.We do not pronounce these letters in english, but in latin. We even say "drive tse", not "drive si".

author: TimFox
author_rank: Super Contributor
timestamp: January 30, 2021, 11:50:18 pm
content: Yes, this NIST table is for SI units. I found the English pronunciation of the names interesting: “kill-oh” (not “keel-oh”) for “k”, which sounds normal to me, personally, and the above pronunciation of “giga”. In spoken English, especially for bit rate, frequency, and resistance, I almost always hear it start with a hard g (gorilla, not giraffe).

author: golden_labels
author_rank: Super Contributor
timestamp: January 31, 2021, 01:44:49 am
content: Quote from: gnuarm on January 27, 2021, 12:48:27 pmIt’s the opposite. “mc” is used instead of “µ” or “u” topreventmistakes. In quick handwriting “m”, “u” and “µ” are practically undistinguishable.

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:38:11 am
content: Quote from: S. Petrukhin on January 30, 2021, 09:06:46 pmI'm an old guy. To me mc is short for mcps which is megacycles per second or MegaHz. I think the ham community may still use that considering they have lots and lots of very old, but not outdated reference materials. Seems like everything in ham radio was invented at least 60 years ago and is just being redone with newer parts and in digital versions, but still the same basic concepts. Sometimes I find the depth of knowledge of some of those guys to be amazing.

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:40:19 am
content: Quote from: S. Petrukhin on January 30, 2021, 10:36:00 pmLol!

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:44:45 am
content: Quote from: TimFox on January 30, 2021, 11:10:17 pmI don't know why you use the term "majuscules" rather than just capitals. Do you often write with uncial script? I've never heard the term before and had to look it up. Is there some special significance this is intended to bring?

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:49:15 am
content: Quote from: TimFox on January 30, 2021, 11:50:18 pmHey, if pronouncing it jiga-watts is good enough for Doc Brown, it's good enough for me.

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:51:48 am
content: Quote from: golden_labels on January 31, 2021, 01:44:49 amThink about that for just a minute. If handwriting is not good enough to distinguish between an 'm' and a 'u', how the hell can it be read at all? Which brings us to another insanity in medicine, the hand written prescription. But that's a bit off topic for this forum.

author: Zero999
author_rank: Super Contributor
timestamp: February 03, 2021, 09:55:17 am
content: I generally avoid using millifarad to avoid this sort of confussion. For values under 0.1F, I use µF, nF or pF. I know writing 22 000µF, rather than 22mF, is long winded, but at least it's unambiguous. I suppose one could write 0.022F, but µF are more common for anything below 0.1F.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 03, 2021, 10:03:07 am
content: Quote from: Zero999 on February 03, 2021, 09:55:17 amIt would be interesting to know this story, when and who decided to make such a joke with the units of capacity.After all, no one says 22 000 micrograms, but they say 22 milligrams. I think someone didn't want to mess with Millie and Micro.

author: Zero999
author_rank: Super Contributor
timestamp: February 03, 2021, 10:47:31 am
content: Quote from: S. Petrukhin on February 03, 2021, 10:03:07 amIn the old days, computers and typewriters had a limited character set, normally just ASCII, plus a few non-standard symbols, such as the local currency sign, so m or M was often used for µ. There was no need for millifarads, as large capacitors above 1000µF were rare and Farad sized units didn't exist, so it wasn't an issue. Nowadays larger capacitors are more common, so we're stuck with the big jump between µF and F and the inconvenience of using five digit numbers for large capacitance values, below supercapacitor territory. It's such a shame they didn't standardise on using u for µ, right from the beginning.

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 12:21:08 pm
content: Quote from: S. Petrukhin on February 03, 2021, 10:03:07 amIf they say 22 grams in place of 22,000 micrograms, they would be wrong. 22 milligrams perhaps, but not 22 grams.While units on a schematic do need to conserve space, in most applications the terms could easily be spelled out. It reminds me of the supermarket receipts. They use 17 characters to describe items which dates back to old days when they first started using computers at checkouts. i remember they had one computer for some 8 or so registers. So memory was an issue and they kept the field size down to keep the systems affordable. Now the MCU inside the laser scanner has more memory than the PC the shared system was based on, but they still use the absolute minimum field width for the description giving us such items as JFC HAP WAS PEA CA. Yum!I don't want my grocery store writing my prescriptions and I sure as heck don't want my doctors writing my grocery receipts.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: February 03, 2021, 12:24:47 pm
content: Quote from: gnuarm on February 03, 2021, 12:21:08 pmFixed

author: Terry Bites
author_rank: Super Contributor
timestamp: February 03, 2021, 01:53:28 pm
content: Somebody stab me please......!!!!

author: TimFox
author_rank: Super Contributor
timestamp: February 03, 2021, 02:04:49 pm
content: Quote from: gnuarm on February 03, 2021, 09:44:45 amUncial letters only exist in majuscule. The terms "majuscule" and "minuscule" are standard English, with unambiguous meanings. "Capital" is acceptable, but the antonym is "small", which I find too cute. "Upper case" and "lower case" are left over from manual typesetting. Capital letters are a well-defined term, but "small letters" could mean minuscule or just a smaller type size (8 point instead of 12 point).

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 10:16:29 pm
content: Quote from: TimFox on February 03, 2021, 02:04:49 pmOk, so if i understand correctly, you are using the terms "majuscule" and "minuscule" to be more clear in spite of the fact that you actually result in being less clear?You say '"small letters" could mean minuscule or just a smaller type size' while the term "minuscule" itself can simply mean a smaller type size unless the reader understands your use of the term... which btw, the first google entry on the search "minuscule type" says, "Minuscule is a typeface for extremely small sizes, which could be used under the commonly acknoweledged threshold of legibility (around 7 points)." So nothing like lower case.The idea of rejecting perfectly clear terms for your own personal jargon simply because they are "left over from manual typesetting" seems a bit... well, I can't come up with an adjective that doesn't sound insulting.Maybe I should just say, I reject your reality and substitute my own.

author: golden_labels
author_rank: Super Contributor
timestamp: February 03, 2021, 10:59:28 pm
content: Quote from: gnuarm on February 03, 2021, 09:51:48 amPrescriptions you get from a physician are not what is of concern. They are not a noticeable part of all places where dosage is used and if dose appears, it is usually used as a part of the medicine name. Not hard to tell what was the original meaning. The problem is with in-hospital use, where each day dosage is written hundreds of times per ward. In that situation the dfference between a short curve — indicating either ‘u’, ‘µ’ or ‘m’ — and a long curve — clearly indicating ‘mc’ — is clear enough to avoid mistakes.Perhaps handwriting is not the ideal method, but so far nothing better has been invented.

author: TimFox
author_rank: Super Contributor
timestamp: February 03, 2021, 11:26:14 pm
content: To gnuarm:Merriam-Webster's definitions of "minuscule" (noun) are "lowercase letter" or "one of several ancient and medieval writing styles developed from cursive and having simplified and small forms". The adjective definitions are "very small" (your favorite) or "written in the style of miniscules" (my preference), referring to the noun definition meaning lowercase letter.I shall continue to use the appropriate words when referring to "case" of letters, which are not "my personal jargon", to be clear and unambiguous.

author: gnuarm
author_rank: Super Contributor
timestamp: February 04, 2021, 03:05:23 am
content: Quote from: golden_labels on February 03, 2021, 10:59:28 pmI'm calling BS on this. Handwritten notes and prescriptions are a WELL KNOWN problem in medicine. But like many aspects of medicine the profession has a holier than thou attitude as if there is nothing they can learn from other professions. I recall watching a documentary over a decade ago about how something as simple as a check list is not used much in medicine. Pilots use check lists. Construction crews use check lists. Virtually every profession uses check lists to help avoid common mistakes. Hospitals seldom use check lists... or more accurately, doctors seldom use check lists. That is the definition of arrogance.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1676338/Dig around a little, you will find much more information on how patients die needlessly because of medical sloppiness.

author: golden_labels
author_rank: Super Contributor
timestamp: February 04, 2021, 07:37:31 am
content: Calling bullshit is very good, as long as one has arguments. Yet the response above is off-topic, not even touching the subject. Suggesting none can be delivered. Even the linked essay, being half-page long, is irrelevant: it misses the claim you are trying to counter (or at least you should). I sincerely even doubt that you have read it in the first place: you have missed that, while referencing a serious problem, it is a piece of humor.If you have some problems with medical staff and need to rant, perhaps there are more suitable places to do so. I am more than completely and utterly uninterested.

author: solder_boy132
author_rank: Contributor
timestamp: February 04, 2021, 08:07:31 am
content: I think I understand now. Im pretty sure its 850uf as in Micro Farad. Thanks!

author: Zero999
author_rank: Super Contributor
timestamp: February 04, 2021, 08:42:22 am
content: Quote from: TimFox on February 03, 2021, 11:26:14 pmAnd, by your own stubbornness, you'll continue to miscommunicate and confuse people.I've not heard those terms used in that context before and I bet you most people don't know what majuscule means, which sounds archaic. Upper and lower case are obvious, well-defined, standard terms, as are capital and small, the latter being clear by the context, as is the case for many other words in English. Take the word lead, for example, which means to cause others to follow, the person in control and the name of a metal, depending on the context.

author: TimFox
author_rank: Super Contributor
timestamp: February 04, 2021, 02:45:50 pm
content: Yes, I am a stubborn curmudgeon, whose motto is "Is that what they are calling it now?".