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.
Member
Joined 2002
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).
R means resistance and is used instead of the decimal point.
The decimal point is sometimes hard to see.
The decimal point is sometimes hard to see.
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...
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...
Dominique said:
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.
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)
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)
Attachments
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
Voltage looks to be NEGATIVE voltage
Is the circuit correct? - Sorry not qualified to answer that one for ya
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.
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.
Hi,
The schematic is effectively drawn upside down and that is causing some confusion
You should be able to improve on the performance of a single transistor.
Look up doug self's site for more detailed info on discrete amplifiers. 1 , 2 and 3 transistor versions as well as discrete opamps. http://www.dself.dsl.pipex.com
There are many other designer's sites to complement that one.
The schematic is effectively drawn upside down and that is causing some confusion
You should be able to improve on the performance of a single transistor.
Look up doug self's site for more detailed info on discrete amplifiers. 1 , 2 and 3 transistor versions as well as discrete opamps. http://www.dself.dsl.pipex.com
There are many other designer's sites to complement that one.
No, the schematic is not drawn upside down, this is a pnp transistor and following normal drawing convention this is the way a simple amplifier circuit would be represented. The only weird thing to most people is that the supply is negative relative to ground. You might find such an amplifier circuit in an old car radio of vehicles with a positive ground for example.
I've used this one as a mic preamplifier. It was my first circuit and I was surprised at how good those few cheap parts sounded!
It works great if you adapt the circuit's impedances to those of the in- and output devices! But it doesn't work well if you got a high source impedance together with a low next stage impedance!
Happy diy-ing!
Dominique
It works great if you adapt the circuit's impedances to those of the in- and output devices! But it doesn't work well if you got a high source impedance together with a low next stage impedance!
Happy diy-ing!
Dominique
- Status
- Not open for further replies.