well...bread board pre amp

[LightSoundGeometry]

I am scared to fire it up and try it ! 

do you think its going to work the first time? i spent probably 3-4 hours messing around with the board tonight .

its the EP3 ..so will it work with 9v or does the echosexy need 18v ?

I added a 47u cap between the 22k and the 9V , will it work as a power filter?

Does the 3k3 and 22n coming off the Gate of the jfet look right on the BB ?

I am going to eat and stuff then kick on the amp & guitar

what should the voltage measurements be? is that something I can derive using the voltage divider principle ?

[LightSoundGeometry]

the signal comes through the guitar to the amp, but the volume level has dropped, cant tell if its adding the high end sparkle like its supposed to. I would most likely guess now from what I can tell

I do have a 9V splitter to turn into 18v ,,maybe i should try it as long as my 47 cap is large enough ?

D - .347 volts

S - .347

G - .1 mv

[antonis]

I added a 47u cap between the 22k and the 9V , will it work as a power filter?

Yew, it will..

Does the 3k3 and 22n coming off the Gate of the jfet look right on the BB ?

I'm not sure because the 3k3 and 22nF are connected between SOURCE and GND..
(maybe this causes your "wrong" measurements..)

[GibsonGM]

Running it on 9V as opposed to 18V will give you less headroom, which you do not need if this is the first stage you are using for a guitar ('stand alone preamp' thing...).   

I would vary the cap value from .22u to 1u or so, to see what tone difference you get.

To adjust (bias) this properly, make R4 (the 22k resistor) a pot wired as a variable resistance.   Dial in the voltage at the drain to about 4.5V, take pot out, measure it, and put a resistor of that value in there.  This will make the FET work equally on both sides of your input signal.

Why do you have a 100K resistor in series with the output?  That's making your signal very low    If R5 was a pot wired as a divider (signal to leg 1, output from wiper, leg 3 to ground), you would have a level control.

Look up "AMZ Mosfet Boost" and see how jack set that up; all you need to do is the same thing, and adjust the bypass cap (that 22n) for "sparkle"...

[duck_arse]

can I make some suggestions because i'm going to anyway?

PLEASE! post a circuit. (if you have, and it's at photobucket, sorry, carry on.)

instead of building across your breadboards, build on one. go up and down its length, this circuit should fit 5 or 6 times on your small board. THEN, when you take/show a photo of your bb, we'll only be seeing circuit connections instead of last months build notes and those leds.

so, put your input at the top of the board (if that makes sense to you) and your output at the opposite end. then build between, with power connections on the long busses. and just the two wires connecting from the supply to your circuit, not to all the other bbs in between.

as antonis says, the 3k3 and 22nF should be on the source, not the gate. BUT, you're circuit diagram might show those connections, and I (and antonis?) can't see it.

[antonis]

Antonis can see the diagram and it's definately the Source that is connectd to 3k3 and 22nF but he can't verify the breadboard population so he stands at LightSoundGeometry statement: "Does the 3k3 and 22n coming off the Gate" and he tries to correct the orientation because it isn't a minor interchange (like Drain - Source)...

P.S.
For my blind downunder friend: 
It's a simple jfet booster with a 22k Drain resistor, a 3k3 & 22nF from Emmiter to GND, a 1M Gate to GND bias resistor, a 22nF Input cap, a 100k - 220pF Lowpass filter before the Input cap, a 100nF Output cap forming a Highpass filter with a 220k resistor and a 100k resistor with unknown (to me) purpose..
(maybe the diagiam is part of a bigger circuit..)

[LightSoundGeometry]

 my Nfet is reading from top to bottom, with flat side facing to my left looking towards it,  and its showing the D,S,G

so I when I twist the legs to fit it in like D,G and then S to the 33k.22n nothing

i cant get anything but a faint signal no matter how I move the parts around ..trying different Jfets, parts etc ..nothing is working


so the input signal goes into gate ? Drain to 9v and source to the 3k3/22 ?

maybe my cheap 20 jfet for 5 dollars are the problem or I am not able to read them right ...somethign is going on because supposedly this is as easy as it gets

I am going to go look at the AMZ one you told me and try it out on BB

I have a photo posted ..I believe its nothing more than the Beavis Audio Jfet buffer/preamp , he calls it the tillman but I seen it called the EP3 or just echoplex ..keep reading how easy these are people are stickign them inside the guitar cavities ..

not sure what I am doing wrong here ..this is going into day 3 now of working on this on the BB with no results . I was thinking its only 8-9 parts there are only so many combinations of ways to hook this up ..woudl that be a permutation or a combination? I cant remember the probability laws lol ..I guess they have to be ordered so it would be a permutation?

[antonis]

so the input signal goes into gate ? Drain to 9v and source to the 3k3/22 ?

Right, but you must have a Drain resistor (like 22k in your schematic) connected to +9V to get some gain..

In theory, it doesn't matter if you interchage the Drain and Source but it DOES matter to do it with Gate...

[LightSoundGeometry]

I gave up on it..I am convinced the schematic is bad

i just made 3-4 other types without any problem ..got my confidence back..

I am wondering a forum member could put the echosexy together on a BB and tell me if it works for them?

I did a SHo and a delux 60 both pre amps turned out just fine

actually really proud of myself - i got the 60's boost in a 1590g which is a huge step forward for me 

only one error and that was the LED on the wrong side, as I had to run wires from the diode instead of going right to the jack ..my soldering was a little off on this one to..for some reason it wasnt bonding to the jacks even with flux ..you can see the rough solder joints on the i/o jacks

[Gus]

The schematic is good.  As posted remove the 100K series output resistor

What JFET number did you use?

You can adjust values for 9VDC operation try 10K for the drain resistor

It is a JFET circuit, and with a simple JFET circuit like this you need to select your JFET or adjust for different JFETs

I have posted about this circuit at this forum and the screenshot shows what I would adjust. 

I would adjust the source resistor(bias) and cap(RC time constant)

A search for Jfet biasing will help.  There are threads at this forum about JFET biasing.  There are things on the web about biasing JFETs

[LightSoundGeometry]

Gus, I am going to give it a shot with your advice. i really want a EP for my personal rig, its become an obsession to get me one.

I went on the "wait list" at chase_tone for one but if I can make one myself and save 200 dollars i will! although his EP clones are gorgeous and probably worth every penny ..I might buy one anyways even if I get mine working

fet was a 2n5457 , tried a 2n5458 to - they have a fD513 on them ..guessing the F is for fairchild

[davent]

This booster is based on the Echoplex, has provisions for doubling your 9v.

http://www.madbeanpedals.com/projects/FatPants/docs/Fatpants2013.pdf

[GibsonGM]

Keep at this one, LSG - you will really enjoy the FET-type boosts, I bet!   The schematic is good. 

Remember: it is very often that parts are touching each other on the BB that should not be, that causes our misery!!
We sometimes plug a resistor etc. in to "+" when it should go to "-"! 
We screw up the device PINOUT...
We sometimes have a bad guitar cord, or power connection to the breadboard.

Why don't you post voltages at each FET pin?   That will help to see what is going on.   Offhand, looks like you have power going to the resistor on the other board...I don't see a + connection to the FET tho - just the output cap!  A wire from D to the 'far end' of that resistor would get you power if that is really the case (so that power flows thru the R, of course.  The output cap is taken from there).  You'd have to route the cap off to your output jack, again, only if what I am seeing in the pic is true.   Not sure of your pinout on that device, sorry...   

>> Your build looks nice...to solder to 'weird things' like that, scuff the shiny up with sandpaper first! Some coatings blow to try to solder to.  Also, grease or production oil will do that, too.