SHO Debuggin

[jayp5150]

I wasn't measuring resistance I was seeing if their was continuity.

I check the datasheets but I will try flipping theJ201.

That's what I was trying to say. Depending on where the pot is positioned, there will be continuity between lugs 3 and 2.

And you wouldn't need to flip the J201, just swap the gate and source by bending the two rightmost legs around each other.

[kurtlives]

Ok I see what are saying about the pot now and I have it wired right then.

I have the pinout of the J201 correct and I am still getting a farty low volume sound.

[earthtonesaudio]

I think the SHO circuit won't work (at least not well... "farting" is not the same as working!) with a JFET unless you mess with the biasing.

...But it will be a lot more static-proof.

[ambulancevoice]

i agree with alex, sounds like the JFET needs to be rebiased

get a BS250, there similar to the BS170 (and i dont think they need rebiasing) and have less noise
but only thing is, there p channel so they need a positive ground supply

if not, you can always get an anti static wrist band and table mat, ground the wrist band to the table mat (they come with connectors) and then install the bs170

[Jered]

  The last two post's are correct for vthe most part. JFET's and mosfet's are two different animals. But you can drop a J201 in the SHO and it doesn't sound half bad. It doesn't have the output a BS170 or 2N7000 does. It just sounds like a medium output JFET gain stage. So if your still getting a farty sound somethings wrong. Have your voltage readings changed?
  Jered

[kurtlives]

Ok I am pretty sure its the transistor...Reasons..

1. The vero board is getting 9V
2. The switch and board seem to be wired perfectly. The switch for sure, the vero should be. I have gone over it countless times and I cant find an issue.
3. I get some audio with a J201 but none with the BS170.

I tried all my BS170s (all were in a zip lock type baggie) not a single one worked.  I have ordered a bunch more from Futurlec, hopefully they come in an anti static bag.

Voltages...
D. 8.23V
G. 7.30V
S: 6.79V then drops slowly

[earthtonesaudio]

If you're concerned about static, just buy some MOSFETs that have a built in gate-protection zener. 

[Jered]

  Chris, try this. Put the J201 back in and get voltages at the drain with the gain minimum, then with the gain knob maxed. Do the same at the gate, and source and post what you get. This will help narrow it down.
  Jered

[kurtlives]

D: 8.19V (min gain)
D: 8.19V

G: 7.74V (min gain)
G: 7.79V

S: 8.18V (min gain)
S: 8.18V

Pretty much identical...thats not right, damn.

[Jered]

  That's with the J201? Voltage didn't change when you turned the gain pot? Wow! Ok, final test, now remove the J201 from the circuit and do the same test. Measuring where the drain would be, where the gate would be, gain knob min/max etc.
  Jered

[Jered]

  hehehe...Chris, I'm messin' with ya. You don't need to touch the gain control. Just see what your voltages are where the pins would be. Bad attempt at humor.
  Jered

[Stratomaster]

I dropped a J201 in mine back when I made it[search thread: "Crackle NOT Okay"].  I didn't rebias anything, and I get tons of output and an amazing sound out of it.  I liked it so much better than the MOSFET, and it seemed to be a lot more reliable.  I did it once, loved it, and never looked back.  I never turn mine off.  Best I can say for a J201 though, is make sure you keep a full 9V of power.  If the battery has drained at all, then it makes a huge difference.  Good luck.

-OMJ

[earthtonesaudio]

For built-in static protection, try the 2N7000KL from Vishay.  Zener protected from static up to 2000V.

Mouser has 'em: http://www.mouser.com/Search/Refine.aspx?Ntt=*2n7000kl*&N=1323038&Ntx=mode%2bmatchall&Ns=P_SField&OriginalKeyword=2n7000kl&Ntk=Mouser_Wildcards

The datasheet on the Mouser site is out of date, I believe.  Vishay's site has the one showing the zener protection.
Here:
http://www.vishay.com/product?docid=72705