Voltage Multipliers (for our tube projects...)

[zambo]

hey casio, you can fire up a 6k6gt at 250 volts ( lower if you want = less watts ) They pull around 37 ma and put out around 3.4 watts. a 2 x 12ax7 preamp would make a pretty wicked amp.
I used a 1363 smps to make one awhile ago. only one 12au7 preamp tube though. http://www.youtube.com/watch?v=pAc2FTzLwbk  . i dont really have a schematic but it was pretty basic. look up the power tube on duncan amps sight. you could just use the p1 schematic too. Good luck. send me a pm if you need anymore info. i dont check in enough on here anymore. Greg

[gtudoran]

Casiomax that is correct but in a preamp stage you will not be even close to 5mA (with nixie modifid smps i've managed to suppy 4 x 12Ax7 without any problems) so if you would like to make a small wattage amp with a 12au7 in PP configuration i guess that could work ... but a El84 i rilly doubt about it. If i can help you with smth or need other comments regarding this PM me or use my mesenger ID.

Best regards,
Gabriel Tudoran
Analog Sound

Hi Gabriel,

again, thx for the input. I know not much about SMPS, but i understand a bit now, changing the oscilator cap means changing the frequency in result different desired output voltage, like you have mentioned before.

I read the EL84 datasheet, if i am not mistaken it requires more than 60mA to operate, as for 12AX7, it only requires less than 5mA, this means firefly project will be able to use SMPS. cmiiw.

Hey casiomax,

You can't supply an output stage tube with this SMPS - don't think that this PSU will supply enough current for a EL84 outputstage. As far as the voltage output goes i was able to sqeez 280v from it (275v with load) - i've changed the oscillation capacitor with 1.5nF as fara as i remember, all the other parts are the same, i also recomand you tu use pcb and a ground plane for this PSU.

Best regards,
Gabriel Tudoran
Analog Sound

[craigmillard]

Hi Guys,

Finally got round to building the nixie supply that rick has posted on this thread!:)

Works a treat upto 250v but i would like to get 300v if possible!

The supply outputs 310v's but if i connect it too 2 12ax7's i get a pulsing noise almost tremelo like, think its moataboating!

The nixie is being supplied by a 12v 2amp powerpack and the parts are exactly as rick has, same inductor and all:(

Can the nixie supply enough current to power 2 12ax7's at 300v's?

any thoughts, or suggestions on alternative power supplies?

cheers
craig

[frequencycentral]

At these voltages you might consider conventional tube amp power arrangements. with four triode stages you've got two sets of two in phase with each other. You'll probabaly combat the motorboating by using a resistor (and a HV cap to ground) to drop the HV slightly for the first and second stage with respect to the third and fourth. That way, stages in phase with each other are seeing different voltages - B1 and B2 respectively.

[craigmillard]

Cheers rick, that is one speedy reply!I Assume your tinkering tonight to then:)

So Your saying instead of supplying the two stages direct from the nixie, Split the supply using a resistor to get a B1 and a B2. say a 1k resistor to both feeds?

           /------ 1k ----- B1
           /
Nixie----
           /
           /------ 1k ----- B2

[Hides-His-Eyes]

Could you output a high frequency from a CMOS oscillator into, a real transformer to get 230V in your pedal without the need for a mains connection inside it?

[frequencycentral]

Like this:



That should drop you enough voltage (10 or 20 volts). Play with the values.  If this were a tube amp you'd have maybe a B2 too, another resistor and cap to get a lower voltage still. Worth looking at a few tube amp schematics to get the idea. Also consider grid stoppers. And maybe adjusting the gain structure by tweaking the cathode resistors upwards slightly.

[craigmillard]

Thanks rick ill give it a whirl and see what happens:)

[craigmillard]

hey guys,

Finally got round to trying ricks suggested ideas! Seems to have helped a bit, not getting squealing but still getting the pulsating effect???

If i play guitar the pulse is only audible if i not playing, its louder if i drag my hand across the strings? It only happens when the gain is turned up?

Sounds mean at low gain settings but want the full range.

The effect i have combined the power supply with is the soldano supercharger gto:

http://hayashimasaki.net/WP2/wp-content/uploads/2010/10/superchargerschematic.jpg

I cant see anything up with the schematic, and have built it on turret board!?

Any further ideas would be a great help?

[zambo]

I am guessing from what i read you have the ps going nixie>>cap to ground>>>>resistor>>>>>cap to ground right? try bigger reservoir caps like in a tube amp. I am using the 1363 smps and running two power tubes ( 12au7) and a preamp tune all off of one smps at 200 ish volts. Its arranged like  I wrote above. capa are 22uf 400v and resistor is 100ohm so i dont drop to much voltage. No squeels etc. it was motorboating a little and scrackling before i did the ps like this though. Hope that helps it..good luck and post results of the gto!!! I want to hear that thing!

[craigmillard]

hey cheers for the fast reply:)

Just before you posted i thought id try a bigger resistor to split the two B+'s worked a treat, 10k minimised it a bit more and 22k has removed it completly!:)
Think some where in the middle might be ideal but only got 22k's at the mo!!

It is a pretty badass distortion!! very soldano:) I like!!

Only issue i have now is that it squeals when nothing is plugged into the input!? Do i need to somehow ground the input when not plugged in, to be fair this isnt on a 3pdt switch yet so that might resolve the issue anyways with a grounded input layout??

[zambo]

im not sure but i think that would squelch it. High gain makes things squeal a lot. Got sound clips of that beast? I am more than curiouse 

[zambo]

after looking at the schematic, the relay switch does ground the circuit when its bypassed. Dont know if it cures the squeal but they did do that. pin 6 on the relay i believe.

[sundgist]

I successfully built the 555 smps - I used the verified layout from Rick, then I tried to do a Vero version too...
Ended up to be a close copy of the perf one...Should work!

I'm just putting one of these together. I noticed the R6(2k2)/C2(100pF) should be on the other side of the diode as in the original schematic and Rick's perf layout.

[sundgist]

Here's a vero layout I knocked up and am starting to build. Based on this schematic posted by Frequency Central and Renegadrian's vero.



I had a piece of stripboard this size so made the layout to fit. The gaps between tracks are really thin on the stuff i've got hence the cut across row b. The jumper from e9 to f10 is on the solder side of the board.
Building now so will verify when done.


edit
*Layout about is Verified working*

[sundgist]

I'd like to make a new topic, did a quick search but there is not a similar one...
So I think it's quite useful to have all the voltage multipliers posted here...

As I wrote in the Valvy topic, here --> http://www.diystompboxes.com/smfforum/index.php?topic=63479.msg597319#msg597319
I wanted to try this circuit here --> http://w1.859.telia.com/~u85920178/power/vconv_01.htm
with 4 trannies and a low number of caps and diodes...
It works, altough I didn't put this circuit in a tube pedal like the valvy yet, I built it successfully, now I got 49.8V from the 14V I got from my unregulated wall wart - did I tell you I finally got a DMM?!  

I believe it will find a good use in a tube project!!!
Here it is, mine has just a stage less to get that 48V

and the one I made...Yellow lines are on the top side.

Here's a vero for the circuit above. Not yet verified but looks good and will be building this later.
Repeat the last stage for more voltage, I only need 48v.

[Renegadrian]

I successfully built the 555 smps - I used the verified layout from Rick, then I tried to do a Vero version too...

I'm just putting one of these together. I noticed the R6(2k2)/C2(100pF) should be on the other side of the diode as in the original schematic and Rick's perf layout.

As you can read here http://www.diystompboxes.com/smfforum/index.php?topic=74088.msg661738#msg661738 Rick made his first version like mine, then corrected it and reuploaded it - guess it doesn't change much, it's just a resistor and a cap to ground. I built mine that way and some other people too and got it working flawlessly, so I just left them that way...

[Renegadrian]

On the other layout, c4-6-8 are 220µ on the original plan.

[blackcorvo]

You know something I just though of trying? Make a self-oscillatiing relay feeding a small transformer (6v+6v) with a center tap in the secondary...

The relay must be a DPDT, so we could use one side of the switch to make the oscillator and the other side to feed the secondary of the transformer. Might be something to try out if you want a REAL portable tube-amp... maybe use one of those 12v/7A sealed batteries...?

 Oscillator
(relay's coil)
__________o            o___X            A ____o            o___ B                                     A ______      __________
(       |           \                                             \                                                                           )||(
(       | +          \ - - - - - - - - - - - - - - - - - - - - \                                                                         )||(             High Voltage
(     ===           \                                              \                                        ________________)||(
(       |               |                                              |                                       |                              )||(              Output
(____|               o                                              o                                     |                              )||(
       |               V+                                           V+                                     |                B ______)||(_________
  ___|___                                                                                           ___|___

[amptramp]

You know something I just though of trying? Make a self-oscillatiing relay feeding a small transformer (6v+6v) with a center tap in the secondary...

The relay must be a DPDT, so we could use one side of the switch to make the oscillator and the other side to feed the secondary of the transformer. Might be something to try out if you want a REAL portable tube-amp... maybe use one of those 12v/7A sealed batteries...?

 Oscillator
(relay's coil)
__________o            o___X            A ____o            o___ B                                     A ______      __________
(       |           \                                             \                                                                           )||(
(       | +          \ - - - - - - - - - - - - - - - - - - - - \                                                                         )||(             High Voltage
(     ===           \                                              \                                        ________________)||(
(       |               |                                              |                                       |                              )||(              Output
(____|               o                                              o                                     |                              )||(
       |               V+                                           V+                                     |                B ______)||(_________
  ___|___                                                                                           ___|___

You have just reinvented the vibrator power supply that was a feature of car radios until the age of the 12-volt plate tubes and 2N176 germanium power transistor.