AMZ FX ANALOG ALCHEMY GEOFX MEF ROG MEF DIY WIKI

Spark Gap: Unusual 9V Hybrid Valve Overdrive

Started by merlinb, January 19, 2011, 12:12:31 PM

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petemoore

#20
February 01, 2011, 11:30:38 PM
   :icon_wink:
  Interesting application for a space charge device !
  Did you have to search for it or did you know what to look for ?
Convention creates following, following creates convention.

Govmnt_Lacky

#21
February 02, 2011, 08:56:16 AM
Quote from: merlinb on January 22, 2011, 06:15:54 AM
I use Evatron enclosures, but since it's 60mm wide I *think* it would fit in a Hammond 1590N.

Are you using PLASTIC cases from Evatron?
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

merlinb

#22
February 02, 2011, 03:55:04 PM
Quote from: Govmnt_Lacky on February 02, 2011, 08:56:16 AM
Are you using PLASTIC cases from Evatron?
No, they're aluminium.

Govmnt_Lacky

#23
February 02, 2011, 04:06:40 PM
Quote from: merlinb on February 02, 2011, 03:55:04 PM
No, they're aluminium.

If its not too much trouble, could you post a link to the enclosure because I could only find  that size in plastic.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

merlinb

#24
February 02, 2011, 04:21:14 PM Last Edit: February 02, 2011, 04:22:52 PM by merlinb

benl560

#25
February 02, 2011, 04:25:13 PM
merlins layout will fit in a 125b hammond without much room to spare.
i would have another one done to post, but i think smallbear forgot about me...

Govmnt_Lacky

#26
February 02, 2011, 04:43:19 PM
Quote from: benl560 on February 02, 2011, 04:25:13 PM
merlins layout will fit in a 125b hammond without much room to spare.

I would hope so because the Evatron that merlin uses is smaller!  :o

Hammond 1590N1 (125B) = 121 x 66 x 40
Evatron EVA60 = 114 x 64 x 30
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

benl560

#27
February 02, 2011, 04:53:46 PM
got me by 2 mils! so close, yet so far away...

i looked briefly for evatrons, but none of the sites i usually buy from sell them. are they nice as far as enclosures go? they appear to have a different "stance"

Joecool85

#28
February 02, 2011, 07:23:04 PM
I'm still looking forward to a sound and/or video clip.  I gotta hear this thing!
Life is what you make it.
https://www.ssguitar.com

BadIdeas

#29
February 05, 2011, 11:33:44 PM
Very intriguing. I don't really understand tubes, so forgive this possibly stupid question, but...
Are the current/voltage characteristics really a function of filament voltage or filament current?

Clearly the tube diode acts differently from the silicon and germanium diodes. I will have to try them some day. What is the filament voltage on this graph?

(From your post on my thread some time back)
How hard can it possibly be to put FRESH vegetables in a can? Seriously.

merlinb

#30
February 06, 2011, 03:53:21 PM Last Edit: February 06, 2011, 03:55:35 PM by merlinb
Quote from: BadIdeas on February 05, 2011, 11:33:44 PM
Are the current/voltage characteristics really a function of filament voltage or filament current?
Strictly it's filament power (temperature) that counts, so you can use voltage or current as the variable. However, "E" series valve have heaters designed for voltage drive -the rated current being approximate- so I stick to voltage measurement in such cases.

Quote
What is the filament voltage on this graph?
6.3V (the rated value). Here's what happens when you alter it. These curves only show what happens at less than 500uA anode current, but that's the region that matters in pedal design.

BadIdeas

#31
February 06, 2011, 07:54:39 PM
Looking again, I'm not sure I like your bypass. Don't you lose treble through the volume pot? Could you use a second BC337 between the output buffer's +input and the 10n cap or just put the existing one there? I don't have the means to cook one up right now, but what do you think? Maybe it's just fine, but it looks like a possible improvement.
How hard can it possibly be to put FRESH vegetables in a can? Seriously.

benl560

#32
February 06, 2011, 10:34:04 PM
hay merlin, are there any problems that you know of with your pcb layout? im not getting any voltage through pin 3 of transistor Q3.  ive checked everything like 5 times, no solder bridges, good joints, etc...
then i did one of those cardboard coca cola box layouts of up til the heaters and...

volla! voltage throughout.
either i got a bad diode or there's an error in that section of the pcb.
just wondered if you knew of an error..

merlinb

#33
February 07, 2011, 07:05:19 AM Last Edit: February 07, 2011, 07:09:21 AM by merlinb
Quote from: BadIdeas on February 06, 2011, 07:54:39 PM
Looking again, I'm not sure I like your bypass. Don't you lose treble through the volume pot?
No, there is no loss. The output impedance of the "ON" transistor is extremely small.

Quotehay merlin, are there any problems that you know of with your pcb layout?
Nope, it's the layout I used! One thing perhaps; the polarity of D2 is not marked (anode to ground), but that should be obvious from the schem.

misterg

#34
February 07, 2011, 12:54:09 PM Last Edit: February 07, 2011, 12:55:52 PM by misterg
Quote from: benl560 on February 06, 2011, 10:34:04 PM
hay merlin, are there any problems that you know of with your pcb layout?

...

just wondered if you knew of an error..


PCB worked for me.... (2nd build, not boxed up yet)

Sound clip of sorts

Here's some noises I recorded through the vero build. No tunes, just single note & chords:

First set clean, then I gradually increase the Fat control to max, back to clean, then increase the Mids control to max (Fat at min), clean again, then increase both together. I think it gives a fair representation of how my build sounds. I tried to be consistent from clip to clip -  Nothing was clipping except the pedal (Single coil neck pickup on a strat copy).

http://www.4shared.com/audio/JSxRgHCk/sg-ts.html



Andy

benl560

#35
February 07, 2011, 07:10:44 PM
ok thanks guys!
there has to be a bad component on there somewhere. ive checked EVERYTHING like 7 times now. i mean, ive stared at this thing for hours now.

oh well. im just gonna make a new board, get some new components, and start again.

misterg

#36
February 08, 2011, 01:36:19 PM
Quote from: benl560 on February 07, 2011, 07:10:44 PM
there has to be a bad component on there somewhere. ive checked EVERYTHING like 7 times now. i mean, ive stared at this thing for hours now.

You've done THIS, right?

Post your readings & a high res, in-focus picture of the top & bottom of the board (taken with a CAMERA, not a f%&$??g telephone) and I'll have a look :)

I think the TL074 is somewhat static sensitive, so you might have zapped it if you didn't take precautions. Maybe try plugging a different one in if you're confident that everything else is OK. (You did socket it, didn't you??)

Andy

BadIdeas

#37
February 08, 2011, 03:16:51 PM
QuoteNo, there is no loss. The output impedance of the "ON" transistor is extremely small.
OK, I get it now. Never mind me. I'm still figuring these things out. Great design.
Through Google Shopping search, I found the 6AL5 available from Triode Electronics, as well as a bunch of eBay listings. Where did you get yours?
How hard can it possibly be to put FRESH vegetables in a can? Seriously.

benl560

#38
February 08, 2011, 04:29:08 PM
yep did all of that.  i dont think its is the tl074(at least not yet) as there is NO voltage on any of the circuit past Q3, the bd435.

my power supply is a steady 9.48 volts
Q1
1, 8.87
2, 9.48
3, 0

D 1N4001
A, 0
C, 9.48

Z9V1
A, 0
C, 8.86

also, ive tried 2 different transistors for q3
i will post some pictures here in a couple hours.

benl560

#39
February 08, 2011, 04:36:29 PM
 :icon_exclaim:
what an idiot!
i believe ive gotten my transistor in backwards.
this is unbelievable. i spent the past 2 days staring at this thing angrily and checking and checking.
today, maybe 3 minutes.

jeeze... well now i can see if the rest of this is right...
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