Fetzer Valve Not working!!!! Aargh!

[Rock_on]

I used 2N5458

And using the calculator from the ROG site and the average values (i dont have a digital MM so I have no idea of what my idss and vp value is)

These are these are the results I get from the calculator (12 Vcc)

Rs 347 ohms
Rd 1317 ohms
Presence capacitor 459.2 or 0.46uF

I can't find any 1.3k and 340-347 ohms resistor.

So i used

1.5k for my Rd and 340 ohms (300 + 40) for my Rs

I got no sound from it and it's SOOOO VERY SUPER ULTRA FRUSTATING!! Arrgh! 2n5458 is expensive, and i dont want to buy that again and again.

Would those values work btw? I need your help guys, really.

Oh btw, im building the Fetzer Valve deluxe version and we have no j201, mpf102, 2n5457 here... Just 2n5458

[duck_arse]

rock, you know the drill:

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

or do you have no multimeter of any description? if not, or even if so, can you post some nice clear photos of your work, we might be able to spot something? your values are close enough to get it working, if not actually fetzering.

it is much harder than you might think to render a jfet useless. start looking at your 1M level pot wiring.

[edit:] by the way, what are you feeding the input with?

[Kipper4]

http://www.runoffgroove.com/fetzervalve.html

[Pojo]

(i dont have a digital MM so I have no idea of what my idss and vp value is)

You need a DMM to setup a circuit like this, no getting around it. There's just too much variance in the way these JFETs are made.

[Kipper4]

I set mine up IIRC to 5.5v that's how I liked it best.
It's a nice little circuit.

[Rock_on]

What do you mean by what Im feeding it with? My guitar, is that what you're asking?

Is there no other way? i have no DMM.

And Im also sure that my pin is inserted correctly...

Source is always the middle isn't (or atleast for the 2N5458), i tried flipping the fet but still no sound.

For the Rd value, which is better 1.2k or 1.5k? And is my Rs useable?

I'll just start over and do the Dead bug wiring.

My 100k is wired correctly, the 3rd is always ground, middle to the jacks, the 1st is always on the board.

Tge 1m pot is also wired correctly, 3rd ground, middle to the board, 1st to the board also (connected to the 33k paralleled with the 220pf)

My power jack is also wired correctly.

[Davelectro]

i have no DMM

I don't get it. You need a DMM to measure your jfet and be able to use the fetzer calculator. 

[Pojo]

It's impossible to debug your circuit and figure out the correct resistor values if you can't measure the the voltages at source and drain. That would apply whether or not you're setting this up to fetzer valve specs or if it's just simply a common source amplifier. Without a DMM that RunOffGroove calculator is absolutely useless to you because it is absolutely critical to setup the jfet test circuit they show and measure your 2n5458 for Idss and Vp. You're shooting in the dark!

I would recommend setting the project to the side until you can pick up a DMM. You don't need anything fancy, even a cheapo $10 meter will be fine and it will be you're best friend next to your soldering iron during your adventures with this hobby.

[blackieNYC]

All good points, essential to getting the best out of it but - dudes-he should be hearing something, no?  Put a pot on the drain and the source and start off with those calculated values if you are determined to not get the meter. (Get the meter). But again, something should come out of it already if these are "typical" values for your transistor. (If the 5458 is among those sample measurements)  Skip the deluxe for now, that cap seems to push it into distortion for me.  You want to hear something.   Anything.

[Rock_on]

To those who are asking... I used the average value posted on the ROG site to use their calculator.

Aw but I really want to build this, I'm not always building styffs that's why i dont have a DMM, and breadboard too!

Im satisfied with my LPB-1 and 5th gear overdrive..

I want this coz it would be like a buffer (coz it has high in and low out) that emulates a fender input stage...

[Rock_on]

Can i just use TL072? Isn't it a FET opamp??

[Ice-9]

Really buy a DMM, you will use it on lots of things and you can buy one for LESS than £3 that will do the job or equiv price in whatever country on ebay
LOOK http://www.ebay.co.uk/itm/DIGITAL-LCD-VOLTMETER-MULTIMETER-CIRCUIT-TESTER-AMMETER-AC-DC-METER-OHM-/190774031117?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2c6b04b30d

No you can't use a TL072 in place of a Jfet, as a tl072 is an op amp not a jfet, TL072 has fet input but it is not the same thing.

[samhay]

I might be missing something - I didn't quite follow your first post, but you can probably get somewhere in the ballpark by ear.
Choose a sensible Rs resistor - 330R might be ok.
Blindly choosing a fixed resistor for Rd is almost certainly not going to work, so use a trimmer (or a pot) for Rd and tweak it until it passes audio.
You should be able to get audio out of it like this, but it may not have the magic harmonic content of the Fetzer.

[Rock_on]

I might be missing something - I didn't quite follow your first post, but you can probably get somewhere in the ballpark by ear.
Choose a sensible Rs resistor - 330R might be ok.
Blindly choosing a fixed resistor for Rd is almost certainly not going to work, so use a trimmer (or a pot) for Rd and tweak it until it passes audio.
You should be able to get audio out of it like this, but it may not have the magic harmonic content of the Fetzer.

This answer... You got it bro! LEMME------ do the job.

But, 330R? Would that affect the Fendery sound? Or just increase the gain?

Btw, should i dial it until it get overdriven or clean or what?


I'll come back here after a week maybe? College works.

[samhay]

Sorry - 330R should have read 340R, or whichever value of Rs you have already chosen.
You should dial it until it sounds good, because ultimately what else matters?