Resistor values

[Stephen]

Hi

The lowest value resistor I have in my junk box is 15k 1/8w. The circuit  calls for 22k 1/8w can I get away with my 15k or
should I use 2 x 15k in series ?

Regards to all.

Stephen

[Steve Gibson]

Hi Stephen,

The lowest value resistor I have in my junk box is 15k 1/8w. The circuit  calls for 22k 1/8w can I get away with my 15k or should I use 2 x 15k in series ?

The value is not super critical, so 15k ought to work well too.  What we care most about is the RC time constant of the R1/C2 pair. So if it's convenient for you to sneak C2's value up a bit above 4700pf, perhaps by the same ratio that you reduced R1, that would tend to hold the time constant steady.  But, again... it's not super critical.

/Steve.

[Stephen]

Thanks Steve, as I have already scrounged the 4700pf from a friend I'll try just the 15k.
Regards Stephen

[Steve Gibson]

Stephen...

Thanks Steve, as I have already scrounged the 4700pf from a friend I'll try just the 15k.

I'm sure it'll work fine.  Your 8khz loudness (with both S1 & S2 depressed) may be a bit diminished, since the R1/C2 combination is there to introduce a time-dependent phase shift delay, and my choice of 22k & 4700pf was an optimal compromise for operation in both the 16khz and 8khz modes.  So the 15kohm & 4700pf combination would biase that tradeoff a bit toward the higher frequency mode at the expense of the lower frequency.

/Steve.