What does the R in resistor value 240R mean? - diyAudio
 What does the R in resistor value 240R mean?
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 16th April 2005, 07:43 PM #1 diyAudio Member   Join Date: Apr 2005 Location: Missouri What does the R in resistor value 240R mean? I'm a newbie in the world of DIY electronics, and was wondering where I can get info on what the R means in 240R resistor on a schematic. I know it's probably a simple question, but I am a beginner.
 16th April 2005, 07:46 PM #2 Banned   Join Date: Apr 2002 240R means 240 Ohm : O )
 16th April 2005, 07:53 PM #3 diyAudio Member   Join Date: Feb 2003 Location: At home 1R8 = 1,8 ohm 10R = 10 ohm 1k2 = 1,2 kohm 12k = 12 kohm 1M = 1 Mohm Get it?
 20th April 2005, 09:50 PM #4 diyAudio Member   Join Date: Jul 2003 Location: S Yorkshire OK The 'letter marker for decimal point' system was introduced to reduce reading errors on schematics; with resistors using 'R' also means you don't have to remember how the heck to get the ohm symbol ( Ω ) - more info here (pdf).
 20th April 2005, 10:17 PM #5 diyAudio Member     Join Date: Jan 2001 Location: Germany R means resistance and is used instead of the decimal point. The decimal point is sometimes hard to see.
 20th April 2005, 11:35 PM #6 diyAudio Member   Join Date: Jul 2004 Location: Berlin to complicate things here's the info I got on caps ratings: QUICK REFERENCE CHART (Decade values) 1R0 = 1pF 103 = .01uF 100 = 10pF 104 = .1uF 101 = 100pF 105 = 1uF 102 =.001uF 106 = 10uF 1010= Some numbers used on 10 meters! I saw that in datasheets too (though you very rarely come across caps smaller than 10pF, so the "R" is hardly ever seen on capacitors anyway) Just to say that "R" probably means something else than resistance in that code...
diyAudio Member

Join Date: Jul 2003
Location: S Yorkshire OK
Quote:
 Originally posted by Dominique to complicate things here's the info I got on caps ratings: QUICK REFERENCE CHART (Decade values) 1R0 = 1pF 103 = .01uF 100 = 10pF 104 = .1uF 101 = 100pF 105 = 1uF 102 =.001uF 106 = 10uF
Those numbers are usually seen marked on the part rather than in a schematic, especially on small caps. A bit like resistors, the first two give the value, the third the multiplier (number of zeroes), result in picofarads, so 472 = 4,700pf = 4.7nF; schematic may show 4n7.

diyAudio Member

Join Date: Apr 2005
Location: Missouri
Cool! Thanks for the info, guys!

What if the schematic reads just 12 for the capacitor (like C1 in the attached schematic)?? I'm having a problem getting it to work. Either my inputs are wrong, my outputs are wrong, or the schematic itself is wrong. I'm assuming the - V coming from R4 is the positive voltage. Would it need more than 9volts (I started low, and worked my way up to 9 volts)
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 22nd April 2005, 07:59 PM #9 diyAudio Member   Join Date: Dec 2003 Location: Cape Town, South Africa I would imagine it means uF or microfarads in this instance. The capacitors shown are polarised. IE there is a + and - pin. The - pin is usualy marked on the capacitor with a big black stripe on the casing. Voltage looks to be NEGATIVE voltage Is the circuit correct? - Sorry not qualified to answer that one for ya __________________ Ross Saunders
 22nd April 2005, 08:11 PM #10 diyAudio Moderator     Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6 This circuit is a common emitter amplifier using a pnp transistor, and the voltage on the collector of a pnp is negative relative to the emitter. Connect the negative side of your 9V battery to V- and the positive side of the battery to the circuit ground. The circuit as drawn is fine, and you can use 10uF electrolytics in place of the existing 12 (uF) caps shown. Kevin Edited to add additional comment.

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