3v Tube Hi-Fi Amp schematic I found.

[bobbletrox]

I was searching for info regarding simple low voltage tube circuits and found this gem that runs on 2 AA batteries:

3v Only Tube Hi-Fi Amp

I wonder if this circuit could be converted into a mini tube amp for guitar or even a tube boost pedal.  1S4 tubes are still available and they're cheap too, in fact there are 2 for $2.95 on eBay right now.  

I'm a total layman when it comes to tubes, but I found this schematic when I was looking for some sort of low voltage tube circuit that could be tacked onto the output of an existing pedal circuit.  Not so it can be overdriven mind you -but rather act more as tone coloration that would only break up slightly if pushed harder.  Is this actually possible?

It'd be kind of like plugging a fuzz pedal into a tiny tube amp and housing it all inside one pedal.  A Fuzz pedal with tube warmth.

[javacody]

I'm curious about this too. I hope someone on the board here has some experience or ideas to offer on this schem.

I wonder how many watts this puts out?

[mattv]

Wow, the output transformer specified is $83.50 at Parts Express

http://www.partsexpress.com/pe/showdetl.cfm?DID=7&Product_ID=3177

[mattv]

BTW, Aron posted a low voltage tube circuit of his that seemed to sound really good.

[javacody]

What the heck is a schmitt trigger?

[mattv]

Simply put, I guess it's an oscillator. Look up the datasheet for that one. Judging by the 150V cap after the smaller transformer, it's helping to do some power supply magic. I wonder how long those two batteries last..

[Johan]

its not a 3volt circuit. it uses an inverter, a transistor and a small transformer to pump up the voltage to around 100-130 volts. the really interseting part is that this particular tube appearantly only needs 3 volt for its heater and must pull extremly little corrent for that heater or the batterys would run out in just minutes...if you replace the output transformer with a anoderesistor ( 10k-100k ) and a capasitor ( 0,01-0,1uF  200volt) you could have a tube-boostpedal that runs on batteries...that would be cool....

Johan

[mattv]

if you replace the output transformer with a anoderesistor ( 10k-100k ) and a capasitor ( 0,01-0,1uF  200volt) you could have a tube-boostpedal that runs on batteries...that would be cool....
Johan

Cool! Thanks Johan! Would the anode resistor just be a series resistor, or does it go to ground?

[smoguzbenjamin]

If battery life is objectionably short you could always use a wallwart. :roll: Although that does make it less portable.

[Johan]

it would be just a resistor replacing the winding in the transformer going from the plate to the voltagesupply

I looked at the datasheet and it says loadresistance-8000ohm, so I guess a 10K resistor would be perfect...

Johan

[toneman]

Hi Tubsters,
the HiV part of the circuit is remarkably similar to the
inverter in the PAiA Stack-in-a_Box (SIAB) kit.
The inverter in the SIAB makes only 40VDC, and the whole
thing runs on a wallwart  instead of  batteries.

Check out my little write up at Frank Clarkes new pages--
http://fclarke.softwareballistics.com/Distortion/DualTubeStackinaBox.html
--mines the TonyB's article---

i'm working on it again!!  I've got the PAiA headphone amp working
awesomely now.  I had a wiring error, that's why the article says i
was dissappointed with it. Not! any more.  It's ear blowing!
Also, very quiet, and very clean.
Now, it's a great headphone practice rig. Need the send/return put
back in soz i can patch in a delay box.  I'm  planning on
removing the 4 speaker sim switches and filling the holes with a
4 band EQ.   I'm reviving my plans for a SIAB with pre AND post
EQs, EnvFol, diode distortion mix-in, and small speaker driver.
LMK if U R interested....
staytuned
tone

[javacody]

I guess I'm still hung up on that schmitt trigger thing. What do they look like? Where would I get one?

[Johan]

74HC14 would probably just what you need..

johan

[Peter Snowberg]

A schmitt inverter uses a little feedback to create "hysteresis". In regular digital, the state switches from 0 to 1 and back to zero as you go above or below a specific voltage. With a schmitt like the 7414, you need to voltage to rise to one voltage to get the 1 and it must fall to a lower "trip point" to get a zero.

Say in a 9V situation you switch at 4.5volts with a normal inverter. The schmitt would require (for example) the voltage to rise to maybe 6V to get a one and then it would have to fall down to 3V to get a 0. The "dead zone" between those two voltages will not cause a change in the output. That makes schmitt inverters a good tool for cleaning up noisy digital signals, or for any application that relies on a signal raising and falling over time, like an oscillator.

Take care,
-Peter

[javacody]

Peter, what do you think of this little design? Useful for a tube preamp?

[Peter Snowberg]

I came across this same schematic in 1997 and thought it was very very cool. Triode Electronics has a ton of really cool stuff on their site.

Never built one, but I'm sure it would be worth the effort as a preamp too. Just replace the Hammond 1650P (:lol:) with a resistor of maybe 22K-100K and use a coupling cap to take the output from the anode.

If you wanted to remain more true to the original, try a Hammond 125A set for maybe 7K, dumping into a resistor instead of the 1650P. That would give you a box heading toward the "herzog device" that was at the core of the Guess Who - American Woman lead tone.

Add some stages and who knows.... you might find sonic bliss.

Take care,
-Peter

[bobbletrox]

I found a schematic of Aron's Shaka Tube, but there's a full project file for it somewhere too isn't there?

http://www.diystompboxes.com/pedals/schems/shakatube.gif

This looks like a tube circuit that won't kill me.

[Ansil]

Application
Miniature type used in output stage of lightweight, compact, portable,
battery-operated equipment. 1S4 and 3S4 are identical except for
 filament arrangement. Requires miniature 7-contact socket and may be mounted in any position.



Mechanical Data

Bulb .......................................... T-5
1/2Outline ....................................... 5-2EIA
Base ...................................... 7AVElectrical Data

Filament CharacteristicsFilament Voltage .............................. 1.4 DC
VoltsFilament Current .............................. 0.1 AmperesMaximum



http://hereford.ampr.org/cgi-bin/tube?tube=1s4