Super Hard On that doesn't feel like working (Debugging)

[LucifersTrip]

bs170 D: 4,66V
          G: 3,70V
          S: 3,65V

Pot (full counterclockwise) (5kohm) 1: 0V
                                                       2: 0V
                                                       3: 3,65V

here are the voltages from mine, which I believe works well

           G      D      S
min   2.81, 7.36, 2.48
max  1.49,  2.98,  .13

[Eric.nail]

about the super duper, that's my final goal, but being a noob, i tought it was a bit pretentious try a double stombox, so i went for the half-version and, if that would have been succesful, i would have coupled it with another one and some exra wiring into a super-duper.

if you (Eric) had bad experiences with the same layout, i feel better with my self esteem, but i would like to dig it some more, and see if the bug lays somewhere else.

It's really not to bad at all! I wouldn't be intimidated by this booster! It's a really cool build, simplistic clean layout. Just need a bit larger of an enclosure. Or really due to the board being so small anyway, You can put it in a really small case anyway! Here's my finished project. I'v added an extra tone knob though to scoop the overall mid and low end range a tad when it's on. The thing gives you all kinds of clarity boost but it can get a little muddy when it overdrives for my taste.

http://img824.imageshack.us/img824/4011/img0364j.jpg
Guts...
http://img841.imageshack.us/img841/9128/img0362zv.jpg

[pinkjimiphoton]

Super Hard On that doesn't feel like working

Try this.

that worked.

damn!

[elmo7sharp9]

I have just built a (basic, no-LED) SHO for a friend and have noticed a behaviour that I have not seen mentioned elsewhere. I'm using a 2n7000 FET.

On breadboard:
At first, I could only get Unity Gain out of the circuit - I tried a teardown and rebuild - same results.
I replaced the high-value bias resistors with a 1M trimmer and was able to dial-in a "sweetspot" for best useability.
Here is what I've found...

Irrespective of supply voltage, the ideal gate bias is 2.29V. Lower than 2.29V and the maximum gain (at the top end of the "crackle" control) drops off progressively, until I'm left with a unity-gain buffer. Biased higher than 2.29v (even at 2.300V !) I start to get a "Dead Spot" at the top end of the "Crackle" control. Naturally, if I change the supply voltage, I have to re-adjust the trimmer.

I have checked for human error, FET pinout transposition, bad FETs (4 times!) etc.

Other than this deviation from the universally accepted (and apparently working for everyone else) bias network, the circuit performs as it should.

[elmo7sharp9]

 
"I have checked for human error"

But not enough, apparently...
I had the topmost bias resistor connected to 9v instead of the bottom of the 5k1 resistor.
I had hand-drawn the schematic to plot a netlist for breadboarding and my error became set in stone.

Interestingly, this accidental variant gives even more gain than the standard SHO (when trimmed for bias = 2.29V) but is VERY much more dependent on supply voltage - it would need re-biased after each battery change or different external PSU.

[Jdansti]

"I have checked for human error"

But not enough, apparently....

Glad you got it figured out!  We've all had this type of thing happen to us.

[elmo7sharp9]

Yes, it's all fixed now...

Tried a fixed 4k7 in place of the pot, with the pot and a 220u cap progressively shorting out the new fixed resistor parallel (for AC). No crackle, but a little less gain at the highest setting of the pot.

Incidentally - why does anybody bother to switch the power off when the SHO is unplugged?

I read 2uA draw at full-tilt and less than 1uA when used as a buffer - the battery life is effectively the shelf-life of the battery!

Why introduce a possible point of failure?
 

[elmo7sharp9]

 
It's always late when I get to do electronics,  and I am - therefore - always prone to end-of-a-long-day stupidity...

Full-tilt draw is 1mA, buffer draw is roughly half that - significant enough to have socket-switching for the battery!

[R.G.]

"I have checked for human error"

But not enough, apparently....

Glad you got it figured out!  We've all had this type of thing happen to us.

It's probably a better Turing Test.

[Jdansti]

"I have checked for human error"

But not enough, apparently....

Glad you got it figured out!  We've all had this type of thing happen to us.

It's probably a better Turing Test.