Is 220R = to 220 ohm - Page 1
Forum section: electronics / beginners

author: shane_95
author_rank: Regular Contributor
timestamp: July 05, 2012, 08:19:07 am
content: i have a packet of resistors and it says its 220R, is that the same as 220 ohm?

author: deephaven
author_rank: Frequent Contributor
timestamp: July 05, 2012, 08:23:57 am
content: Yes. They normally put 'R' because the omega symbol isn't in the standard character set on PCs etc.

author: Psi
author_rank: Super Contributor
timestamp: July 05, 2012, 08:29:14 am
content: you also sometimes see 4R7 which is 4.7ohms or 4k7 which is 4.7k

author: shane_95
author_rank: Regular Contributor
timestamp: July 05, 2012, 08:38:13 am
content: Ok awesome

author: EEVblog
author_rank: Unknown
timestamp: July 05, 2012, 11:04:27 am
content: Quote from: Psi on July 05, 2012, 08:29:14 amEasier to say too. "Four Kay Seven" vs "Four Point Seven Kay"Dave.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 05, 2012, 11:07:35 am
content: Quote from: EEVblog on July 05, 2012, 11:04:27 amYeah,one word less!

author: caroper
author_rank: Regular Contributor
timestamp: July 05, 2012, 11:23:13 am
content: It is also a lot easier to read on a schematic for us folk with older eyes1R2 is obvious but if you replace a 1.2 Ohm with a 12 Ohm because you didn't see the microscopic decimal you have problems debugging your circuit.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 05, 2012, 02:07:09 pm
content: Quote from: caroper on July 05, 2012, 11:23:13 amI have older eyes,but I've never had that problem!

author: Rufus
author_rank: Super Contributor
timestamp: July 05, 2012, 02:31:37 pm
content: Quote from: vk6zgo on July 05, 2012, 02:07:09 pmTry it when all you have is a grotty scan to work from like this

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 05, 2012, 02:33:54 pm
content: I think the decimal point thing has more to do with the quality of reproduction using photocopying and faxing of schematics, back in the days when PDF wasn't yet around.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 05, 2012, 03:22:20 pm
content: Quote from: Short Circuit on July 05, 2012, 02:33:54 pmThe rectangles for resistors were to save draughtsmen work.Now we can use wiggly lines like I was brought up on!

author: chrome
author_rank: Regular Contributor
timestamp: July 05, 2012, 07:01:08 pm
content: Quote from: vk6zgo on July 05, 2012, 03:22:20 pmNot everyone uses that silly symbol for a resistor, over here we use the rectangle.

author: Zad
author_rank: Super Contributor
timestamp: July 05, 2012, 08:20:04 pm
content: To my mind, the zig-zag line is the more correct way of denoting a resistor. The rectangle denotes any impedance block, which may be purely resistive, or it may have an imaginary or complex impedance value. Some standards bodies agree, some disagree...I tend to use the 4K7 method when sketching, it is easy to lose a decimal point drawn in faint pencil.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 06, 2012, 01:04:52 am
content: Quote from: chrome on July 05, 2012, 07:01:08 pmThe point I was making,was that the wiggly line was annoying to draw,hence the rectangle.With computers,there is no difference in difficulty.I don't think the wiggly line will ever die out,it is still used by so many people.The important thing is that we look at a rectangle or a wiggle,& they both say "resistor".

author: EEVblog
author_rank: Unknown
timestamp: July 06, 2012, 01:07:18 am
content: Quote from: caroper on July 05, 2012, 11:23:13 amTry reading the decimal point on Digikey bag labels!Next to impossible, and I have perfect eyesight.Dave.

author: shane_95
author_rank: Regular Contributor
timestamp: July 06, 2012, 11:59:41 am
content: Im looking at a CONTINUITY TESTER Circuit, and it says it needs 10k, 30k, and 1k resistors. Does that mean 10,000, 30,000, and, 1,000 ohm's?

author: vk6zgo
author_rank: Super Contributor
timestamp: July 06, 2012, 12:16:16 pm
content: Quote from: shane_95 on July 06, 2012, 11:59:41 amYep!Strictly speaking,the "Ohm" sign should follow "k" in each of these cases,but it is often neglected,because:(1) It isn't a letter on the standard keyboard.(2) If it is followed by the word "resistor" in a parts list,or written adjacent to a resistor symbol on a schematic diagram,the "Ohm"suffix is implied.By the way,a "30k" resistor isn't one of the so-called "preferred values"--you would probably use 27k or 33k.Why "preferred"?I could tell you,but it will probably be better explained on the 'Net,if you Google for it.

author: shane_95
author_rank: Regular Contributor
timestamp: July 06, 2012, 12:38:49 pm
content: I did the google, i now get it

author: G7PSK
author_rank: Super Contributor
timestamp: July 06, 2012, 02:55:03 pm
content: Try these links.http://www.diyaudioandvideo.com/Electronics/Color/http://www.electronics2000.co.uk/data/itemsmr/res_val.phphttp://www.electronics-tutorials.ws/resistor/res_2.htmlIt also gives the preferred values and the reason for them, start with the last link as i think that it makes the clearest explanation if you read down the page.