JFET Splitter

[j.d.roost]

Hello.
Building the Jfet splitter tonight and I have a few questions.
In the original schematic here.

http://www.muzique.com/lab/splitter.htm

r1 (10m) is inline before c1. But in the pcb layout here .

http://www.muzique.com/images/split3.gif

Its placed after the cap.

Also
R4 (10k) in the org. schematic is connected to the + side of c2/ground and r5 (100k) connects to the - side then to output.
This is reversed in the pcb layout (r4 10k hits the - side of cap/ground/output and r5 100k grounds the + side of the cap).
So what layout is correct?
Does it matter?
Thanks.
JD

[ianmgull]

I'm not sure about the output cap but the input section doesn't matter. The pulldown resistor (r1) can go on either side of the input cap.

[j.d.roost]

Ok, that helps with the 1st problem (thanks fo rthe quick reply).

Hope someone can help out on the others.
JD

[ianmgull]

As for the second part of your question if the output electrolytic cap is reversed that absolutely would matter. It's hard to tell though because there is no parts overlay in the second image you linked to, only the pcb transfer.

[j.d.roost]

Sorry about that.
Layout here is not labeled..
http://www.muzique.com/images/split4.gif
You need to go toward the bottom of the page of the 1st link to see parts .
http://www.muzique.com/lab/splitter.htm
(sorry for all the links... my picture host is down right now)

As you can see r4 and r5 are swapped from the original diagram.
Thanks again for your time.
JD

[ianmgull]

The layout looks fine to me. On the parts overlay you posted the polarity of the caps aren't even labled (nor are the specific resistors). The output is taken from the source of the FET. It then goes through the output cap and the 100k to ground.

Does this answer your question? I'm not sure if I'm understanding you properly.

[Leston Braun]

When building this thing for a bass player, should one make any other modifications than increase the input cap, maybe to somewhere around 0.68uf?

[PRR]

> increase the input cap, maybe to somewhere around 0.68uf?

? ? ?

The proposed 0.1u value against 2M2||2M2 gives a -3dB point at 1.5hz, -1dB at 3Hz, and unmeasurably down at the lowest note on a bass. It does not have to be increased.

> before c1... ...  placed after the cap.

The unmarked split3 diagram appears to be correct.



Yes, the IN "hits" the C before the 10Meg, but if the copper is a perfect conductor then you can connect the parts anywhere along the conductor. Copper is not perfect, but it's only 1/4" difference, and against 10,000,000 ohms the 0.001 ohm "long-path" resistance is utterly insignificant. Schematics show parts for best thinking (or should); layouts place parts for best fit or best electrical performance.