"5840 Boost" Submini Pentode Booster using 5840 Pentode

[frequencycentral]

Yes yes, I know, yet another frequencycentral submini tube circuit. Boring boring boring! This is the story, forum member Toney recently "stumbled across a metric ship-load of EF72 (or CV465, 5840) submini pentodes from some guy that buys military surplus.  I have ordered a test batch which will arrive tomorrow." He kindly sent me a few with a challenge to design something for them, they arrived a couple of days ago.

The other good news is that these tubes are not even slightly microphonic, as is often the case with submini pentodes. The heater requirement is 6.3 volts / 150ma. They glow a real nice orange too. So I'm planning to revamp a number of my old designs using these little tube, and maybe do some new designs too, basically for the common good of all mankind. I cut my teeth on this little boost, just to check the tubes out really. To power the heater I just put two tubes on the breadboard and ran the heaters together in series from a 12 volt supply. Probably the easiest way to power the heater in a pedal would be 7806 voltage regulator. More 5840 designs to come...........

5840 data sheet: http://frank.pocnet.net/sheets/127/5/5840.pdf

[Renegadrian]

You have so much time to experiment! (put an envy face here)
I wish I had more time to experiment, actually I just made one, and played around with the 6AU6 schem someone else did, changing some parts to fit a submini pentode (6205)
I still haven't managed to build every single project you developed! Damn!!! I want to try this one!!! (and create some more myself...) - thx for your efforts and your will to share them...

[biggy boy]

Cool
Hey do you have some sort of sweat shop going at your place making these circuits up?
Or do you just never sleep?

Looking forward to seeing some pictures when the time comes.

Glen

[Renegadrian]

6205 are a version of 5840 with high shock rating and with the suppressor (G3) coming out on a separate lead (so can be tied to  cathode, ground or a DC voltage) otherwise these are interchangeable with 5840 as well as some other subminiature pentode tubes.

For more info please see spec sheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/137/6/6205.pdf

Taken from an evilBay ad.

[Toney]

Champion!

Looks wonderful, Rick and I can't wait to see what else you do with these babies.
You are very much "the man" when it comes to these things.

[frequencycentral]

Important: please don't PM Toney asking to buy tubes, he's not in the mail order business!

Hey do you have some sort of sweat shop going at your place making these circuits up?
Or do you just never sleep?

I spent a couple of hours today in a frustrating breadboard wrangle with opamps, I breadboarded this boost to relax afterwards! Tubes are like being 'home' after solid state. Admittedly the three Russian scientists I kidnapped and hold hostage help out a great deal in the lab, but I have to do a lot of the work myself.......

[Ripthorn]

Crap, more tubes to buy.  The wife isn't going to be happy...

[Renegadrian]

As 5840 are quite identical to the 6205 I've been playing with, I want to share my layout...

http://www.diystompboxes.com/smfforum/index.php?topic=76372

[tranceracer]

Yes yes, I know, yet another frequencycentral submini tube circuit. Boring boring boring!

I for one don't think your creations are not boring!  I find all of them very inspiring and creative.   Looking forward to hearing clips of these puppies too!

BTW, not sure if this was mentioned in another thread but what graphic program are you and Renegadrian using to draw up these schematics?

[Renegadrian]

GIMP. a lot of patience and cut copy paste...

[tranceracer]

Thanks Renegadrian!

[Johan]

if you want to use tube-sockets for chassis mounting , EF95/6AK5/5654 is the same tube as 5840 in a 7-pin miniature bottle, about half the size of a 12ax7
j

[frequencycentral]

Yes yes, I know, yet another frequencycentral submini tube circuit. Boring boring boring!

I for one don't think your creations are not boring!  I find all of them very inspiring and creative.   Looking forward to hearing clips of these puppies too!

Aw shucks! 

BTW, not sure if this was mentioned in another thread but what graphic program are you and Renegadrian using to draw up these schematics?

MS Paint  As Adriano says, lots of cut and paste. I got the tube symbol itself from the Tung Sol data sheet.

[doitle]

Anyone have a sound clip of this thing? I'd love to hear it and then order a tube from Aron and get this thing started.

[frequencycentral]

Yep, worth mentioning that 5840 subminis are now available in Aron's Store: http://diystompboxes.com/zencart/index.php?main_page=index&cPath=19

[earthtonesaudio]

Hey Rick (or anyone who wants to chime in),

I just salvaged some 5886 submini pentode/triodes and I was wondering if you might have a circuit suggestion for them.  They are high gain, low voltage, and the cathode is direct heated (I think that's the correct terminology).
Datasheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/127/5/5886.pdf

Thanks!

[frequencycentral]

Hey Rick (or anyone who wants to chime in),

I just salvaged some 5886 submini pentode/triodes and I was wondering if you might have a circuit suggestion for them.  They are high gain, low voltage, and the cathode is direct heated (I think that's the correct terminology).
Datasheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/127/5/5886.pdf

Thanks!

Hey Alex, pretty similar to 5672 in many ways, here's a pinout comparison:

5672 pin 1 = 5886 pin 1
5672 pin 2 = 5886 pin 2
5672 pin 3 = 5886 pin 3
5672 pin 4 = 5886 pin 7
5672 pin 5 = 5886 pin 4, except that it would appear that this is also the filament -ve.

The heater appears to want 1.25 volts / 10ma, an LM317 would be a good option. But my calculations suggests a 1K ¹/₄ watt resistor would drop the voltage nicely. That current draw is measly! The plate voltage is really low at 22.5 volts.

So try it out in a Pentaboost type circuit, then cascade two for a Pentadriver. Look at Delirium if you want tremolo, but you may have to tweak the 43K/47K voltage divider. All the schematics are easily accessible by the link in my signature. Have fun, expect microphonics!

I'll take this opportunity to shamelessly plug the follow-on circuit from the 5840 Boost: "Promiscuous Girlfriend" .


EDIT: Also have a look at tranceracer's 6418 build: http://www.diystompboxes.com/smfforum/index.php?topic=76388.msg624839#msg624839

[earthtonesaudio]

Thanks Rick!  I was thinking you had to take the grid more negative than the filament...  Guess I should read up on tubes some more.

[Toney]

For those that VERO....

http://www.aronnelson.com/gallery/main.php/v/Toneys-Album/Booster+5840.gif.html?g2_imageViewsIndex=1

[iccaros]

Rick

Do you mind If I barrow this booster with my  linear Low voltage tube project, I plan on using a 6112 in front of this the same way I was using a  12AX7 in-front of a  6AU6.

Thanks