Voltage Multipliers (for our tube projects...)

[rotylee]

shouldn't this be called "charge pumps" thread.?

i built i tremolo with this "multiplier", rick mentioned rick earlier and its discussion was dropped.

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   Re: Voltage Multipliers (for our tube projects...)
« Reply #79 on: May 31, 2009, 02:58:07 AM »
   
I found this over at AX84 forum, thought it may be useful to some folks:

PDF: http://ricktone.rickcampbell.org/cgi-bin/getimg.cgi/PedalPowerSupplyLayout.pdf

Link to thread: http://www.ax84.com/bbs/index.php?id=385353
<<

my comment is isn't brute force and lower part counts better except for space considerations ?

[Renegadrian]

http://electricwestern.com/diytubes.html

seems interesting...

[zambo]

Im just using small power transformers at this point. There are some cool toroidal's im going to try when i get the cash.

[waltk]

Here's my version of the nixie power supply described in numerous posts above.





If you build this layout, don't forget the jumper under the 555.



Here's a link to the full-size PCB image: http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=46574&g2_serialNumber=1

They work great.  Now I just have to find something useful to do with them.  I have a few spares if anyone is interested.

[Renegadrian]

http://powersupplycircuit.net/wp-content/uploads/2011/07/dc-to-dc-converter-circuit.gif

[Toney]

  
I am looking for ways to achieve 50-150v @ 10mA for submini tubes.

Reading this thread a few times I think the two most useful candidates are the much discussed Nixie power supply and Harry Lythall (SM0VPO)'s multiplier design.

Nixie here: http://www.ledsales.com.au/kits/nixie_supply.pdf
Harry's here: http://www.sm0vpo.com/power/vconv_01.htm

The Nixie is a great unit but as designed it is adjustable between ~100 and 200v and can put out 10mA. Perfect! But I would like the voltage to start at a lower point ~50 V or so. I think to get it lower, its simply a matter of adjusting the feedback voltage divider, reducing the 220k resistor (R5 on the schem). What I'm unsure of is the effects this may have on oscillator noise (actually I am unsure of many parts of this Lol).
Sungist mentioned on the previous page measuring 18kHz with the trimmer fully adjusted down to 90v with this unit which would possible cause noise.
So how to lower the starting voltage and keep the oscillator out or audio range?

Harry Lythall's design is very simple. He says it can produce 1-2 watts of total power and states it will do 100mA @ 24v which I get as more like 2.4 watts. This up-scales to 50mA @ 36v (1.8watts) and 30mA @ 60v (1.8watts) so approximately 10mA (maybe) after losses @ 150v if you build that many add on stages.



I would like to build this, but using a beefier transistor pair for more "reserve" current.
Any suggestions as to best replacements for the BC547/557?

[Toney]

 OK, while I am waiting for my Inductors to arrive I have put together this:

                             

It 'aint the most compact thing but by utilizing the %^&*roft-Walton capacitor approach, you can get up 93v from a 9v supply, using common low-voltage caps and no special components required. I used all 33uF 16v caps, simply because I had a bag of them. You can pretty much build this from any types you have within reason over 10uF. You can also use other common tranny types such as 2n3904 for the astable multivibrator bit. I used a combination of 1n4001 followed by 1n4148 for the diodes which are a bit lossy.
Obviously as voltage increases, current is reduced so you will only see 3-4mA at 90v but that may be OK for some single tube designs. At lower voltages there is much more current to play with. You can tap off whichever voltage you need or build it up to the required voltage. You could also tighten the layout up a bit if you wish. I built it as shown with PCB pins so I can tap off different voltages.
Schem is in post above, layout is verified

NOTE: Even at low current please take care with higher voltages

EDIT: Had to change the image link. (willy word in the title)

[merlinb]

[Renegadrian]

nice, but 10mA enough to power just one tube?! I don't remember the usual plate current of the common tubes, but 10mA is really low...

[craigmillard]

1-2ma for a 12ax7.. should power a full preamp rack unit!

[Dongle]

Hi!
I build this 555 voltage multiplier - seems to work. I want to put it in my tube pedal with one or two 12ax7.
Right now, I just switched it on alone, not buid in any pedals... I am a bit afraid of the high voltages.
If I connect the metal housing of my pedal to the gnd (signal and voltage multiplier) - will I be safe than? What else should I pay attention to - just to avoid dying?

[amptramp]

Hi!
I build this 555 voltage multiplier - seems to work. I want to put it in my tube pedal with one or two 12ax7.
Right now, I just switched it on alone, not buid in any pedals... I am a bit afraid of the high voltages.
If I connect the metal housing of my pedal to the gnd (signal and voltage multiplier) - will I be safe than? What else should I pay attention to - just to avoid dying?

Voltage multipliers have notoriously poor regulation - the voltage may drop some if you touch it (but don't touch it just to check).  I have been repairing and restoring antique radios and televisions since I was a teenager in the late Jurassic period and it is possible to get a shock but if you follow safe practices like not holding onto anything grounded, you will be OK.  In fact it was far more common for me to get burns from hot tubes than any electric shock injury.  Once you ground the negative side to the chassis, it would be more possible to get into trouble with the positive lead because now you have a large grounded box to touch as well.  You should also follow the star grounding schemes recommended in a few other threads where all ground connections are brought to one point so that you don't get ground loops that allow current to flow from one grounded point to another and add noise.

Check the voltage you are getting at the output.  Each triode in a 12AX7 is normally operated below 2 mA and is usually 0.5 to 1 mA.  The filter capacitors store most of the charge and this is where current will come from if you touch it.  If you are measuring voltages, make sure your hands do not contact the metal part of the probe, but most test leads have an insulator with a hilt on it to make sure there is little possibility of coming into contact with high voltage.

[Dongle]

Alright... thanks!
Still I am wondering: If I have that thing ready in my pedal and do not connect the housing to anything - than I might get 200 V on the housing if I get a failure (loose cable etc).
So O thought, if I connect it to ground, the circuit would be short - that would not be dangerous and one would notice the failure...

[amptramp]

The housing will eventually have to be grounded at one point, usually the input jack, to avoid noise pickup from having the housing floating.  If you are testing the power supply with the housing floating and it accidentally touches the +200 volt line, then the rest of the voltages in the circuit will be negative with respect to the housing.  But as I said, with reasonable care, you should not run into any danger with a 200 volt supply that can only supply a small current.  The televisions that I worked on in the past have had 270 volt supplies with 150 mA capability and that is not the highest voltage in the set - the damper supply was usually 550 volts and the high voltage to the CRT was in the range of 12,000 to 25,000 volts.  Only rarely would anyone get into trouble because all probes are insulated for any test equipment you would want to use.

[merlinb]

Just adding another one to the list:

[Zozobra]

Just dropping by to say wow, this is a very useful thread!  I've come into possession of a reasonably powerful laptop PSU (19VDC@7.1A)  and I was toying with the idea of building a hybrid amp and the converters here will be ideal!  I'll be sure to post up my build when it is on its way.  I'll probably start with something like an Alembic preamp with an output buffer/loop into a cheap class D poweramp board.

[GibsonGM]

Hi Zozobra, welcome to the forum!  Yeah, this is a very neat thread, really useful info on how to power your tubes without laying out the ca$h for transformers. I'm also working on some flyback-type power (just the nixie stuff, nothing special), and was checking out the schematics here, and saw your post.

So, you want to go tube pre, to SS output?  Not a bad choice if you don't want poweramp distortion. Preamp dirt is easier to control, more predictable  

[Zozobra]

Thanks   A few of the regulars will no doubt have seen my witterings on other techy forums.

That's the plan.  I've built quite a few push-pull tube amps and I fancied trying something different.  Certainly hybrid amps like the Matrix VB800 and Verellen Kalaloch look very interesting and it would great to have a light weight, high power pedal platform in the arsenal!

[duck_arse]

also hello Zozobra, and are you planning for 6V or 12V heated valves?

[GibsonGM]

Since we're reviving this thread, it seems...has anyone been able to source the 100uH inductor lately? 

I've been thru my usual haunts (Mouser, Newark etc) can can't seem to locate a suitable replacement - the listed parts appear to be out of stock permanently...