jawari ?

troubledtom · December 24, 2003, 12:27:17 PM

hey all , i got some extra time to mess around. so i made a jawari. it has very low output , i don't think that's normal . is it ?
i'm not a transformer expert by any means. but i figured since the primary[sp?] and other side were the same value it wouldn't make a differance the way i wired it, true?
the only parts i changed was the ge diodes , i used other ge diodes that i had.
the circuit is wired perfectly believe me i checked over and over again.
now that i have egg splatered all over my face i'll wait for a little help :oops:
peace and thanx,
- tom

petemoore · December 24, 2003, 12:39:28 PM

Your deescription fits my attampt perfectly...what are the odds of that?
I dunno but Im pretty sure somethin's 'funky' with mine...yep I looked it over under awhile sideways and down but still I think there's something amiss...because it doesn't work right er sounds more like an octave thing.
It went to the 'backburner' section...[set aside]...I'll watch to see if anything gets figured I could use to try again with this ckt on this topics..

sfr · December 24, 2003, 02:30:41 PM

I was looking at the Jawari today, and noticed some differences between Charlie's perf layout at Moosapotamus and the current schematic up on Tim's site. Specifically, the version on Tim's site has the center tap of the TF going to ground, and Charlie's has it going to Silicon Diode. There might be some more differences. Has there been some updates to this circuit? Sounds like it from the Moosapotamus site. Might building the "older" version using Charlie's layout yield better results? Anyone care to comment on the differences between the two? I know there were a lot of people building this circuit and loving it, but the last couple of times it's been mentioned people have been less than thrilled. Maybe I'll breadboard both versions of it and see if there's a difference, but not 'till after the holiday.

troubledtom · December 24, 2003, 02:37:32 PM

huh, yep !
sounds like the same thang. it's a drag bacause my devices are 10 times harder to build and 8 out of 10 times they fire right up.
i've been meaning to build the jawari for a long time , i hope i haven't wasted my time. i'd really like to get it working in all it's greatness.
i have a vg-88 v.2. that gives killer sitar sounds , but that's beside the point.
peace and thanx again,
- tom :?

Tim Escobedo · December 24, 2003, 04:09:48 PM

The Jawari isn't very loud at all. However, it should be at least unity gain. The diodes used should have low forward voltage, such as Ge or Schottkys. Assuming the transformer is a 10k 1:1 windings, it doesn't seem to matter which side is used as a primary. Also, it works best with single notes rather than chords. Lastly, it's meant to be used with the bridge pickup. Using a neck pickup sounds like a weak octave up circuit.

troubledtom · December 24, 2003, 04:19:56 PM

Quote from: Tim EscobedoThe Jawari isn't very loud at all. However, it should be at least unity gain. The diodes used should have low forward voltage, such as Ge or Schottkys. Assuming the transformer is a 10k 1:1 windings, it doesn't seem to matter which side is used as a primary. Also, it works best with single notes rather than chords. Lastly, it's meant to be used with the bridge pickup. Using a neck pickup sounds like a weak octave up circuit.

it's not even close to unity gain :?
thanx for any help tim! you have alot of great ideas!!
peace,
- tom

troubledtom · December 24, 2003, 04:47:57 PM

Quote from: sfrI was looking at the Jawari today, and noticed some differences between Charlie's perf layout at Moosapotamus and the current schematic up on Tim's site. Specifically, the version on Tim's site has the center tap of the TF going to ground, and Charlie's has it going to Silicon Diode. There might be some more differences. Has there been some updates to this circuit? Sounds like it from the Moosapotamus site. Might building the "older" version using Charlie's layout yield better results? Anyone care to comment on the differences between the two? I know there were a lot of people building this circuit and loving it, but the last couple of times it's been mentioned people have been less than thrilled. Maybe I'll breadboard both versions of it and see if there's a difference, but not 'till after the holiday.

tim ? what do yah say bro ?
- tom

troubledtom · December 25, 2003, 09:44:43 AM

bump

mattv · December 25, 2003, 07:18:29 PM

I haven't built this one, but on Charlie's layout, the center tap is connected to ground, as is the cathode of the silicon diode - same as Tim's schematic. I noticed that Charlie didn't include the 1k between the silicon diode and ground though, and there's no output cap. Not to mention the feedback loop and all that fancy stuff.

I wish I could say why your circuits aren't working right.

Travis · December 26, 2003, 12:21:49 AM

I built this from Charlie's layout, and I had the same problem. WAY below unity. I covered most of the difference with a 1M volume pot, but it is still very quiet.

Could this be a p/u problem? I generally use low output single coils.

troubledtom · December 26, 2003, 08:04:03 PM

i'll bump this mofo for a week til tim get's back , if need be :twisted:
- mot

nightingale · December 27, 2003, 12:31:57 AM

Quotei'll bump this mofo for a week til tim get's back , if need be
- mot

LOL! not sure why i'm still laughing... must be the word "mofo" in print... oh man!! anyway, i still have a populated jawari board put away somewhere... it's been a while, but i think mine was close to unity... and with the right pup settings i think i got some okay sitarish sounds... i will fire it back up when i get back to my bench tomorrow...

Travis · December 27, 2003, 01:19:33 AM

N, did you follow Tim's schem? I think that I may jump back into mine and redo it per the schem. 1k resist, etc. Strange that that would kill it so effectively, though.

smoguzbenjamin · December 27, 2003, 07:46:42 AM

Guys, what about adding a JFET stage at the end to crank the volume? :?

nightingale · December 28, 2003, 12:24:45 AM

travis~
yes i followed tim's schem to specs... it was over a year ago... so if the schematic has changed at all lately, it would be the "older" version that i tinkered with...

i remember using the exact transformer winding that tim uses... and the 1N34 diodes that he calls for... i still have not returned home, but i will be home pretty early tomorrow morning... this thread has kind of sparked some interest in this circuit again... i'm eager to dig that board out of the retirement box... hopefully between the four of us we can figure it out... lol!

Tim Escobedo · December 28, 2003, 12:49:55 AM

I'm not sure where the problems are. I'm not aware of any layouts specifically that are floating around. I did see one once several months ago and it seemed OK, but I didn't try building it.

The circuit is a full wave rectifier driven by a low gain stage. The very low forward voltage characteristics of the rectifier diodes gives it a distinctive sound and dynamic behavior at such low gains. The schem I have posted is DC coupled. This may cause a problem if you're feeding it with a DC bias, but that seems unusual. The biggest potential for problems seems like it would be misoriented transistor or diodes or possibly the wrong transformer.

I have had reports that several different types of transistor did work in the circuit. I had tested several brands of J201, but not other types.

Travis · December 28, 2003, 02:34:32 AM

http://www.geocities.com/tpe123/folkurban/fuzz/jawari.gif

and

http://www.moosapotamus.com/jawari/JawariLayout.gif

Aside from the obvious mods, which I did not apply, the principal differences are the 1k resistor between the si diode and ground (missing in Charlie's layout) and the output cap (also missing in Charlie's layout). I did use an output cap of .1 uF.

I forgot the schem at my office, and so built it according to the layout at moosapotamus. If I can find time today, I'll go in and bring it up to spec. I really like the sound of this thing, very proto-punk funky. Unfortunately, the volume drop kind of kills the effect.

troubledtom · December 29, 2003, 08:55:03 PM

to the top.
i 'm not gonna do it again.
if i have to breadboard the circuit and mod it . then i wished i'd not seen the schemo in the 1rst place. if i have to do that i'd design my own. but it's cool.
i work on my own devices, z said to me a long time ago ,to keep doing
what i'm doing and make a name of wwww.troubledvariance.com
i simply took a day to F(*^ around and it didn't work out , for now at least. best wishes to all !!!!!!!!
peace,
- tom

nightingale · December 29, 2003, 10:41:25 PM

yeah~
i dug mine out of the circuit graveyard shoebox... mine is built exactly to specs on tims site... mine is a hair louder than unity...
no offense to at all tim, but lets just say it's not gonna make it to my pedal board...
actually, messing around with my rambler last night... i was able to get more pronounced "sitar" type effects... i love the ramber.. also, with the right guitar settings... my friend described them as ring mod sounds...
pretty cool tho!

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jawari ?