dumb newbe question...regarding trim pot use...help please!!

[pinkjimiphoton]

i tried googling, and looked at brother beavis's excellent resource on the matter, but i'm all confused ...

i want to change the circled resistors to a trim pot so i can get more gain from the first fuzz circuit.. (chip is a 741)

i've tried hooking it up with the ever-present roach-clips-and-wire, and it definitely is working...kinda...

i'm using a rat shack 100k trimmer (closest thing they had in stock) but i can't figure out the proper way to hook this thing up!!

what seems to work best is to use it in place of the 39k resistor, and connect it to the 820 ohm resistor....any other way (like bypassing both and using just the pot alone) doesn't seem to work.

my question is, 2 parts...

is the lug on the trimmer that is in the middle (two on one side, one in the other, kinda in the middle) the wiper?

do i have to connect the other two terminals together, or am i cool just using it as a variable resistor since i'm leaving the 820 ohm resistor in place?

or am i completely missing something? it seems to me, i should be able to just use the trimmer in place of the two resistors, correct?

shoot...i guess that's three questions!

thanks in advance!!!!!!!!
peace
jimi

[deadastronaut]

i would think a 50k trim would be ok in there...thats what i would try anyway..thats closest to 39k.....

yep! lug at one end is wiper...

treat them as pots..

  2  *
  3* 1*   stars are lugs...... put 1 to ground like your 820 is...if you are doing it without the 820 that is...


in on 3...out on 2...ground on 1..../ or 2 out to your 820...

[pinkjimiphoton]

i'll try that as soon as i get home, rob...thanks! if it DOESN'T work , should i leave the 820 in, maybe go to a 1.5 or 2 k? it seems right now when i turn up the pot, about the same time i get the volume boost it gets kinda muddy...wondering if that's from not changing the 820 too?

no matter...i'll mess with it when i get home...thanks again!

[LucifersTrip]

If you want to keep the circuit the same, you can't sub 1 trim pot for 2 resistors that are split by another signal.

I would just sub a 50k trim pot (or a normal 50K pot) for the 39K. You can even put a 180K resistor across the 2 lugs of the pot you are using to turn it into a 39K pot....or the 100K could be cool with values above 39K.

You should definitely have some type of meter for these projects so you can measure across the pot lugss so you can easily see which is which..

btw, what 's the actual name of that..A pink jimi photon?

good luck

[pinkjimiphoton]

hi lu...love the name!! heh heh...

i got it working...when all was said and done, i swapped out the 820 ohm resistor for a 2.2k, and replaced the 39k resistor with a normal full-sized 50k pot with the wiper and third terminal connected...worked like a charm! now the "fuzz 1" is adjustable for a couple db above unity, and the gain pot actually functions....a completely different animal, it's like having a fuzz and an octavia in one box. very sweet!!

what's the name of the fuzz? it's actually this....



http://www.hobbytron.com/GMDoubleFuzzBoxKit.html   ....best 10 bux i ever spent!!
it's close enough to the circuit in the pic at the beginning of this thread that i figured i'd just use the schem to ask my question...
and it turns out that jamie and rg actually drew up the schem back in the early 90's...too cool.

as for me, well...the pink came from an excursion involving 14 windowpanes and the pink floyd movie the wall...some friends christened me pink...the jimi came from me mum, i always spelled it jimmy, but she started callin' me jimi....and the photon came from a biker i used to work with, no bloody idea why, lol...

anyways...this is a very groovy and cheap kit, comes with everything but the stompswitches and the box. i added a 3pdt switch with an led for fx in/out, and a dpdt to select fuzz/octavia with a couple led's to show which is on...red for fuzz and green for octave. now that the fuzz gain is sorted out, this puppy will get a permanent spot on my pedalboard!



thanks for the help and advice, peeps...most righteous!
peace
jimi

[LucifersTrip]

hi lu...love the name!! heh heh...

i got it working...when all was said and done, i swapped out the 820 ohm resistor for a 2.2k, and replaced the 39k resistor with a normal full-sized 50k pot with the wiper and third terminal connected...worked like a charm! now the "fuzz 1" is adjustable for a couple db above unity, and the gain pot actually functions....a completely different animal, it's like having a fuzz and an octavia in one box. very sweet!!

what's the name of the fuzz? it's actually this....



http://www.hobbytron.com/GMDoubleFuzzBoxKit.html   ....best 10 bux i ever spent!!
it's close enough to the circuit in the pic at the beginning of this thread that i figured i'd just use the schem to ask my question...
and it turns out that jamie and rg actually drew up the schem back in the early 90's...too cool.

as for me, well...the pink came from an excursion involving 14 windowpanes and the pink floyd movie the wall...some friends christened me pink...the jimi came from me mum, i always spelled it jimmy, but she started callin' me jimi....and the photon came from a biker i used to work with, no bloody idea why, lol...

anyways...this is a very groovy and cheap kit, comes with everything but the stompswitches and the box. i added a 3pdt switch with an led for fx in/out, and a dpdt to select fuzz/octavia with a couple led's to show which is on...red for fuzz and green for octave. now that the fuzz gain is sorted out, this puppy will get a permanent spot on my pedalboard!

Sounds great. Some of the coolest fuzzes come from the oddest places.  Coincidentally, I'm in the middle of building a Heathkit Fuzz..another fuzz sold as a kit in the 70's (maybe 60's?).

That Double Fuzz Box schematic may be considered a classic on a forum a decade from now...haha. Sad, they're sold out.

Regarding the name..good one. I'll just say SV

[pinkjimiphoton]

saint vitus...i likes it!! reminds me of the daze of my youth!! good stuff, bro...is that you? fuzzy feedbacky wah-d out goodness!

[deadastronaut]

@jimi...glad you got it going man...any soundclip of it?..

[pinkjimiphoton]

hi rob, i'll try to up a clip in a little bit! bear with me, cuz i don't really know what i'm doing, lol!!!


gonna try and layout a veroboard eventually, i'm just messing with diy layout creator right now for the first time...what a cool program!!

either i screwed up the true bypass, or it needs an input buffer, it's kinda muddy when bypassed...but sounds killer when on...the fuzz is very smooth and fuzzy, kinda "blooms", but the octave fuzz is SCREAMIN'...

this is my mockup for a simple buffer i found on beavis's site...i THINK i got it right, was trying to make it as small as possible:



if this looks alright, i'll build it on a tiny piece of vero and add it to the circuit...and maybe to your tremolooooooooooooo, too...

i know the cut at e 7 is redundant, that was leftover from an earlier attempt...ooops!

[deadastronaut]

great...

look forward to the clips..

yeah bancika's prog is great!...i use it lots for just trying small stuff...

ive tried a few fuzz's and never found one i like enough to box...they always get ripped off the breadboard after a couple of hours...if that!..

[LucifersTrip]

saint vitus...i likes it!! reminds me of the daze of my youth!! good stuff, bro...is that you? fuzzy feedbacky wah-d out goodness!

no, those guys are doom legends from LA...started in the 70's. They were always one of my favorites...and still do an occasional show!
http://en.wikipedia.org/wiki/Saint_Vitus_%28band%29

The vocalist, Wino (who usually plays guitar also) is considered an underground god, kind of like what Lemmy is to rock n roll:
http://en.wikipedia.org/wiki/Scott_Weinrich

[pinkjimiphoton]

great...

look forward to the clips..

yeah bancika's prog is great!...i use it lots for just trying small stuff...

ive tried a few fuzz's and never found one i like enough to box...they always get ripped off the breadboard after a couple of hours...if that!..

i hear ya,....fuzzes can be killer, or annoying...or both! i have been digging on them, kinda revisiting the fuzzy goodness of my youth. gonna be building a couple kay fuzz clones soon, that was my first fuzz, and i wanna build one for a bud of mine (who is horribly ill) who gave it to me in the first place back in the early 70's.

i REALLY dig the bobtavia...if ya build the one that lifts the transformer, ya get a nice overdrive, too...octave up's can be really cool.

i think fuzzes seem to work better stacked, without being pegged...like most dirt, less is more sometimes. hope ya find one you like!!

lu, thanks for the info...it's cool stuff, reminds me a lot of my youth!!

[deadastronaut]

great...

look forward to the clips..

yeah bancika's prog is great!...i use it lots for just trying small stuff...

ive tried a few fuzz's and never found one i like enough to box...they always get ripped off the breadboard after a couple of hours...if that!..

i wanna build one for a bud of mine (who is horribly ill) who gave it to me in the first place back in the early 70's.

good man...be a great prezzie..

[pinkjimiphoton]

i hope it makes him feel better. he's been battling metastatic renal cancer for the last 6 or 7 years now. one outrageous electronic mandolinist...like sonny sharock on pure lsd...
and a good dose of special k (i can vouch for the acid, not the ketamine, lol)...google up woden thoth or electric tiger.

the guy is sick!!