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Old 29th April 2007, 08:55 PM   #1
haziz is offline haziz  United States
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Join Date: Apr 2007
Default Resistor value in 3875 and 3886

Is there a typo in the parts list in the 3875 kit instructions from Audiosector? I just finished the premium kit, but was thinking of building the regular kit and was thinking of ordering the parts myself, partly as an exercise to reduce my fear and apprehension regarding ordering parts. The kit will end up being more expensive than Peter's prepackaged kit. I have wracked my brain however for the last 2-3 hours due to uncertainty regarding the value of the phoenix (or other brand) resistor. Is it 220 Ohms or 220K Ohms? It makes a difference of only 1000! The kit also intermittently refers to the 22K resistor as 22K and 22.1K. Does it make a difference? As far as I can see Digikey stocks resistors (by Phoenix) of both values, though I may be missing subtelties regarding composition and properties.

One other possible typo is in the Digikey parts list on the last page (p. 26). The parts number for the 220 "Ohms" resistor leads to a listing for a 20K resisitor.

Also is this 22.1K resistor used in the kit the same as the one in Peter and Brian's LM3886 kit?

I am enclosing a quote from the instructions PDF (LM3875)

Parts list (p 5 in PDF):
PCB containing board for 2 channels and 2 rectifiers
LM3875TF - National Semiconductor chip amplifier
1500uF 50v - Panasonic FC Capacitor
22k ohm – Phoenix SFR16S resistor (R2 and RNFB)
680 ohm – Panasonic Carbon Film 0.5w resistor (R3)
220 ohm - Phoenix SFR16S resistor (R1)
MUR860 - On Semiconductor fast diode
4.7uF 100v – Panasonic FC capacitor

Cut from p 26 of PDF
22.1k ohm resistor (min quantity = 5)

220 ohm resistor (min quantity = 5)

Any chance of getting a Digikey parts list for the LM3886 kit with the regular and possibly the premium components suggested by Peter and Brian?



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Old 29th April 2007, 09:09 PM   #2
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Location: Sydney/Australia
hi haziz,

You can assume Peter's parts list is correct. Hundreds have been built and any errors would have been discovered and fixed years ago.

220 ohms looks right.

22k and 22.1k are effectively the same. I'm sure this is a result of what was in stock at the time of ordering parts.

Greg Erskine
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Old 29th April 2007, 09:46 PM   #3
cpemma is offline cpemma  United Kingdom
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Location: S Yorkshire OK
221 is, I think, the "official" Standard EIA value in the E96 resistor range between 215 and 226; the more common E24 range quotes 220, which, in 1% tolerance, is near enough identical.
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Old 29th April 2007, 11:40 PM   #4
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Default Re: Resistor value in 3875 and 3886

Originally posted by haziz
Is it 220 Ohms or 220K Ohms? It makes a difference of only 1000! The kit also intermittently refers to the 22K resistor as 22K and 22.1K. Does it make a difference?
It is 220R and the value of that resistor is not critical. I often don't install it at all (use jumper in its place). Also, it can be as high as 1K without much difference.

The pdf manual was not written by me, and it's posted on my site mostly as general info. The parts listed on ordering page indicate currently used values (220R, 2 x 22k, 680R)

There isn't any noticable difference between 22K and 22.1K resistor values, it could be 23K equally well and things won't change much.
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
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