2sk170 pinout on schematic

[Rawkcraze]

okay so im trying to clone this MAD little green wonder pedal, but ive never taken a circuit class in my life so i dont really know how transistors/mossfets are printed on schematics.
heres the schematic: http://revolutiondeux.blogspot.com/2008/07/bjf-lgw-little-green-wonder.html (if you click in image it gets larger.)
can anyone tell me what the top, middle, and bottom (with the arrow) are? like which pin is which.
from some websites they say the arrow points to the gate, and others say the source.
the pinout for the 2sk170 is DGS instead of DSG of other mosfets.
thanks so much.

[Earthscum]

Well, first of all, the 2SK170 is a JFET, not a MOSFET (I'm not emphasizing to be mean, lol... it's Junction Field Effect Transistor, vs. Metal Oxide Semiconductor FET)

Jfets bias a little different than MOS do. The way it's used in the schematic is as a buffer. The 2SK170 Datasheet shows that it is an N-channel JFET, like the more well known J201, or just about any common JFET.

I honestly don't know why they have the symbol drawn like that, but the input is the Gate, the part that goes to V+ is the Drain, and the part that is "out" and connects to ground through the 10k resistor is the Source. Easiest way to remember, for me, is that JFETs "Source" electrons from GROUND (negative charge, electrons are negative charge), and "Drain" them to the Positive rail. The "Gate" is, obviously, the control for current flow. Some rare instances call for a aJFET to be connected differently, but there is usually a clear note indicating that it is not a typo, please note this, etc.

[PRR]

> I honestly don't know why they have the symbol drawn like that

That's just wrong. They should upgrade their schematics tool.



FWIW: in this circuit and this device, the Gate is the key connection. CHECK the pinout of the JFET you get and be sure it goes toward the Input. The Source and Drain are essentially interchangable on a JFET in audio uses. This means with a center-Gate pinout such as genuine 2SK170 you can put the part in either way.