where to buy a 7k9 resistor?

[JohnForeman]

i'm putting together my stock list for my next build, a GuitarPCB SWAH and it calls for a 7.9k resistor that i cant find on the smallbear website.  does anyone know where i can get this value?  Or would it be safe to sub with a 7.5k or 8.2k?  I dont want to use substitutions without making sure you guys say it's ok.
thanks
-John

[Jdansti]

Looks like you're talking about R27. Since this resistor is in series with a trim pot, it's just there to limit the lowest resistance when the pot is turned to it's lowest setting. You'd probably be fine with either a 7.5 or 8.2.

[JohnForeman]

yup.. R27 is the one.  any suggestions on which way to go with it?  up or down?
thanks for the reply.. still working on the stock list so i'll probably have more questions.

[R.G.]

I don't know the circuit in question, but I have this big suspicion that (1) a resistor in series with a trimmer is pretty arbitrary and (2) 7.9k is so nonstandard a value that there may well have been a typo in entering the value on the documentation.

Here's a handy place for resistor values: http://www.logwell.com/tech/components/resistor_values.html

If I remember right, 3.9K is the only two-digit 5% value ending in "9" and 7.5K is the only one starting with "7". Even in 2% or 1% series, the value 7.9K doesn't occur, although 7.87 is pretty darn close.

I'd agree with J.D.'s advice: stick in a 7.5K or 8.2K, but I'd add be prepared for it to be a typo and have a 3.9K in hand. Murphy is like that. 

[Jdansti]

As R.G. mentioned, you might want to get a few 7.5k, 8.5k, and 3.9k. If you order from someone like Tayda, the resistors are about $0.012 ea.  That would run you about $0.11.   

[davent]

For oddball resistor values (or simply common values i'm missing) i use an online reverse-parallel resistance calculator. Plug in the value you seek 7k9, tell it the tolerance you're willing to tolerate and it spits out all the pairs of common values that yield a value within your stated  parameters.

http://www.sengpielaudio.com/calculator-parallel.htm

dave

[armdnrdy]

If you must have a 7.9K resistor....look no further my friend!

http://www.mouser.com/ProductDetail/Vishay/RN65C7901BB14/?qs=jZi1jxfVU94YBOScB1o8sw%3d%3d

7.9Ks as far as the eye can see!!

[PRR]

I assume there is a missing VA connection on the schematic to Q2 Q3.

http://www.guitarpcb.com/PDF%20Files/SWAH%20v3.pdf

R27 >= 1.95K or you could burn the chips (if you turn TR1 all the way).

R27 really never needs to be much smaller than R26 (6K8). That would be very-mild effect. In most cases you want R27+TR1 set much larger than R26. That's why TR1 goes to 50K.

I'd use anything between 1K95 and 5K. Really, whatever several-K resistor I had too many of (in my drawers, usually 3K3).  Sure not gonna pay a buck + shipping.

[Jdansti]

>(in my drawers, usually 3K3)

I think anything over 1k in your drawers is somewhat kinky.

[JohnForeman]

Great feedback guys.  When I figure out why the notes on the guitar go together like they do,I'll try to figure out why these electronic bits go together like they do..  Until then, its comforting to know you guys are so willing to help those of us that simply glue these things together and hope they work!
Thanks again
-John

[duck_arse]

you could always replace the 7k9 with a 10k trimpot, set to 7k9 .......

[midwayfair]

(2) 7.9k is so nonstandard a value that there may well have been a typo in entering the value on the documentation.

BJFe likes using completely off-the-wall values sometimes. Like the two 31.6K biasing resistors in the Honey Bee OD. Maybe it's cynical to say so, but I would be dollars to donuts that it's so that exact clone are less likely ... most people won't go through the trouble of getting weird resistor values that are almost completely arbitrary and have no discernable effect on the sound anyway.