GGG P45

[Kipper4]

Thanks guy. It goes from q1 to positive of the cap.
I'm gonna have a go at matching some fets as soon as I get time. Mines subtle in character.
I must have tried 30 fets before I settled. I'm gonna see about getting a c500k too. I must check my pot stash.
Maybe it's the 500k with 510k in parallel trimmer that's making it subtle. The way I set it was to max out the speed pot and listen for the spot with the most tremolo effect I could get.

[disabled_shredder]

The effect is subtle in nature somewhat like a rotary or soft vibe. U will have a pronounced phase shift in the mids almost like playing w The tone knob. And rg @geo wrote a paper on pots I'm pretty sure how to make a log pot reverse log. Worth a look!

[Kipper4]

I reversed the pinout on the log pot already thanks.
I'm gonna try some rc4558 op amps too and see where it gets me.
Thanks for the help.

[disabled_shredder]

Never tried other op amps let me know how the sound is.

[Kipper4]

no better. hmmmmm.

[duck_arse]

kipper, what fets did you end up using, or are still sorting? I really should get to breadboarding this, like I've been gunna.

[Kipper4]

I just tried every 2n5457 then j201 and the best so far are the 2n5458s. MPF102 are next on the list.
Transistor roullete again. Just 'cause im too goddam lazy to make that simple fet matching board and do the work.
I'll get round to it one day.
breadboard it please and let me know how you likes it.

[bluebunny]

Transistor roullete again. Just 'cause im too goddam lazy to make that simple fet matching board and do the work.

Really mate, it's worth the teeeny amount of effort!  It'll take up a small postage stamp area on your breadboard.  You know you want to!   

Seriously, without reasonably matched FETs, it just plain won't work.

[Kipper4]

I'll do it tomorrow now. Thanks mate. I need to read up some more to know how to match them well. Somehow I'm not getting a lot from the RG  article. Mind you I had the same issue with the pnp germanium tester. I'll get there.
I know I want to.
I'm gonna get a piece of corrugated card board and as I test them number them and match them from a data base sheet. When I understand the readings.
Thanks for the encouragement Guys

[disabled_shredder]

Use the jkm jfet matcher it has a pcb image and its easier to perf and its plain and simple just pop the fets in hook up the dmm and get the readout. I've built 5 of the p45s and look for a 1.4-6 v it's more common for me I never get 2.5-6 what matters the most in my experience is that they are within .1 v dc if they match and are over 1.2 they work. But like duck said its a must to build a matcher otherwise your building a dead pedal. I can't breadboard and that matcher took me 10 mins to rig up. Worth a million if you perf it so you can throw it in the test jig bin. And don't feel bad about the ge tester I got one but can't fig out the math. But hey trial and error. We will get it just got to look forward not down. And don't be afraid to leave the project alone for a while the best help is knowing when to give it a break bc your brain is over loaded sometimes walking away and coming back to it later will reveal the mistake and you'll have an aha followed by a s@/t moment. Then you flip a component and be playing In no time! Let me know why happens.

[Kipper4]

Thanks Dizzy
I'll be sure and let you know how it goes dude.

[bluebunny]

I'll do it tomorrow now. Thanks mate. I need to read up some more to know how to match them well. Somehow I'm not getting a lot from the RG  article.

Good for you for wanting to understand it.  But just build the circuit (here) and simply take the readings.  Two that are within a couple of percent (so 0.0x volts) are "matched".  You'll probably get some bang-on, depending on the size of your batch.  Then you can do this!    

[Kipper4]

Mark. What are you doing to me?
85 fets later and they're all on sheets marked up.
When i get back in a bit i'll try some in the mini phase 45.
thanks guys
btw i had my DMM set to 20v DC. Should it be set differantly?
the variations are wild especially between differant fets j201,2n5457,2n5458,mpf102.
Does it matter if i mix and match them as long as they're closely matched?

[bluebunny]

Mark. What are you doing to me?
85 fets later and they're all on sheets marked up.

LOL!     I mean, er, sorry Rich!  (But you know it makes sense!  85?  Wow...)

btw i had my DMM set to 20v DC. Should it be set differantly?
the variations are wild especially between differant fets j201,2n5457,2n5458,mpf102.
Does it matter if i mix and match them as long as they're closely matched?

I don't think the DMM setting matters.  I don't see why different FETs, but closely matched, shouldn't work?  (But I'm prepared to be educated otherwise.)  Perhaps R.G. might like to chime in here to elucidate...?

   

[candidate]

who is jkm?

[duck_arse]

@ dis /dizzy - seeing as you said I said it, I'll say it - the fet matcher is a must build.

rich, rich, rich. buy yr fets in lots of 100. suppliers love that. then blob the top of each with white, and number each. jamb them one by one into yr new-made tester, and write the value. THEN stick the # and value into a spreadsheet, and graph the results. makes finding close matches easy, and you can work out the % mismatch with the spreadsheet, as well.

my personal taste, I tend to avoid j201's in circuits wanting resistance varying, and save them for amplifing. the 2n54xx, mpf10x, j210, bf245a/b/c, all have nice low resistance channels. plenty of people would say j201 is fine/ has used, probably, so don't listen to me.

[disabled_shredder]

Candidate jkm is a website that does DIY. I think he offers boards for the taptation and other things. I found that site through the madbean forum I think. His jfet tester is easier to work w. I don't know what it is about me but if I don't have a board to follow I can barely understand a schem. I know terrible! My mentor gets on to me a lot about it. I can read schems but its hard wo a board layout. I guess I need to physically be routed first. I'm a 1920s phone call! Aggghhhhh! But either way just google jkm DIY or jkm boards and check him out. He has some neat stuff going on and kipper if you have a 9v setting go for that honestly if your not reading above a lower setting put it on a Lower setting set it On that so you can get a more accurate number.

[Kipper4]

Thanks for the help Dizzy shredder, Mark, Duck Arse and all.
I found the j201 not terribly good for this application.
Its a fine balance getting it set right with the trim pot too.
How I did it was set the pot for the fastest setting (tremelo effect) and trimmed the pot till it did it.
I wasnt sure if there was a more scientific way. I'd be greatful if someone knows of one if they could share it.
I read somewhere that its possible to make it flange a bit depending on setting the trimmer. but i cant see that happening.
It works fine now, still subtle but when bypassed you can tell its there.
I prefer the slower settings tbh.
I love the fact i've been able to make one.
Next time i think i'll do a phase 90 for more of the effect.

[Kipper4]

I've just been over it with the DMM and found a few flaws, corrected now and sounds much better.

[Kipper4]

I've set it up with 2x mpf102
1.93v in Q1
1.92 in Q2
it swooshes nicely now and sounds sweet as a nut on all but the fastest setting when it becomes almost indicernable

I like it best with the

1 strat neck pup
2 PRS Santana neck or both
3 matsumoku les Paul neck pup
4 Tele Baja mod pup setting
5 Passive bass a bit odd but a usable special effect
6 Cort B4 active bass    meh!!!!!!

I love it now