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Author
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Topic: Voltage Multipliers (for our tube projects...) (Read 51328 times)
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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A verified layout for the Nixie SMPS, I just built and tested it today. It's putting out 313 volts without a load. I haven't added the snubber yet, I want to experiment with that part. The snubber is made up of the 2.2K resistor and the 100pF cap in the Nixie schematic. I've an idea that changing the snubber values slightly will keep the B+ higher, so I thought I'd build the main part and hook it up to my breadboard to test different filterings. I used two 100uF caps instead of the 330uF, mainly to save on space. Here's the link to the original file again: http://www.ledsales.com.au/kits/nixie_supply.pdf   |
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Ice-9
Posts: 1156
Mick T Newcastle England
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Thats looking really good Rick, and 313v as well. Were did you get that inductor i think i will build this SMPS to try with one of my 12ax7 designs.
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Rebel without a clue.
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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Thats looking really good Rick, and 313v as well. Were did you get that inductor i think i will build this SMPS to try with one of my 12ax7 designs.
Thanks guys. The inductor is this one: http://www.rapidonline.com/Electronic-Components/Inductors-And-Chokes/Leaded-Inductors/High-current-leaded-suppression-chokes/79278/kw/The SMPS is for my next amp. I've got some 12AX7 and 12AU7 left over from my Valvecaster builds last year, and I bought a bulk lot of Fender Reverb Transformers (for my Murder Ones), so I thought I'd try a SE amp with 'proper big tubes' and a SMPS. Just for fun, I connected the SMPS to a 9 volt battery today - and got 254 volts! I titter'd me t!ts off! Completely useless to consider a 9 volt battery powered tube amp though. |
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tranceracer
Posts: 592
-bK
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Just for fun, I connected the SMPS to a 9 volt battery today - and got 254 volts! I titter'd me t!ts off!
LOL!  |
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Ice-9
Posts: 1156
Mick T Newcastle England
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Just for fun, I connected the SMPS to a 9 volt battery today - and got 254 volts! I titter'd me t!ts off! Completely useless to consider a 9 volt battery powered tube amp though.
Yeah ! but to get 254v from a 9v battery is just something you have to try just to see it for real. Lol |
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Rebel without a clue.
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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Here's a variation on the 555 SMPS with the addition of a negative charge pump section. Probably of interest to only one person on the planet (me), but developed so I can play with negative grid biasing my 5902 beam pentodes. Verified today on the breadboard. The red stars indicate where it is possible to tap off -11.5 volts and -22 volts, possibly useful for negative grid biasing other tube types.  |
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« Last Edit: November 01, 2009, 12:10:51 PM by frequencycentral »
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earthtonesaudio
Posts: 3489
Alex
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Does this require a heatsink for the FET?
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I gotta cut down on my (ab)use of parentheses.
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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Does this require a heatsink for the FET?
Yeah, the IRF740 gets pretty hot. Without thermal dissipation it would eventually burn out I believe. I used the simplified version (ie without the negative charge pump) in my Superfly, there are pics of the heatsink I used in that thread: http://www.diystompboxes.com/smfforum/index.php?topic=78302.0 |
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maarten
Posts: 138
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Hello Rick,
why did you move the 2K2/100p to the other side of the 1N4004?
Maarten
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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Hello Rick,
why did you move the 2K2/100p to the other side of the 1N4004?
Maarten
Bummer! My mistake, I'll correct the layout and schematic......  |
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Cliff Schecht
Posts: 1187
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It looks like a snubber circuit to me which goes in parallel with the FET's drain and source terminals. Or in this case, because you've got voltage-mode control, it goes from the drain to ground. These can increase efficiency in the FET by 20-30%, sometimes more with excessively ringing circuits!
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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Hello Rick,
why did you move the 2K2/100p to the other side of the 1N4004?
Maarten
Bummer! My mistake, I'll correct the layout and schematic...... Ok, both the layout and schematic (above) are now corrected. You may need to refresh your browser to see them. Oops.  |
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g.
Posts: 151
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thanks for sharing !
i'm curious,
how many mA this supply can output ?
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frequencycentral
Posts: 4880
Kicking the sh!t of of your speakers since 2008
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^ ^ Not sure how to measure for how many ma it puts out.  I was thinking that it should be possible to double the ma output by dupilcating the IRF740, snubber, inductor, diode and reservoir cap. ie two parallel SMPS running from the same 555. Obviously the current draw would be significantly higher, but using each of the parallel outputs to drive one dual triode (in a two dual triode design) should give significantly higher voltages and increased performance before saturation of the inductors occurs. |
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crystal
Posts: 2
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Neat design, but I do wonder why you've connected the negative grid biasing circuit to the gate of the mosfet. As long as there is virtually no load on the negative rail you will be fine else it will reduce the efficiency of the mosfet because the gate isn't driven hard enough. Wouldn't it be better to connect the negative charge pump to the drain of the mosfet?
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Cliff Schecht
Posts: 1187
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^ ^ Not sure how to measure for how many ma it puts out. I was thinking that it should be possible to double the ma output by dupilcating the IRF740, snubber, inductor, diode and reservoir cap. ie two parallel SMPS running from the same 555. Obviously the current draw would be significantly higher, but using each of the parallel outputs to drive one dual triode (in a two dual triode design) should give significantly higher voltages and increased performance before saturation of the inductors occurs. You would have to sync the two oscillators to prevent beat frequencies from occurring. Just being 30 Hz off is enough to give you audible noise.. Also, I'm not sure how well a direct duty cycle supply will handle being paralleled. Current mode supplies are good at this because both can sense when the load has changed and will adjust accordingly. Direct duty cycle control OTOH just knows that more current = more duty cycle. One of the supplies may be able to try to pull too much current and fail. It may not be a problem with what you're trying to do but it's something to be aware of with simple switchers like these. |
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niopren
Posts: 56
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thanks for sharing !
i'm curious,
how many mA this supply can output ?
Nixie PS max. 10ma just for one or two 12a*7 |
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g.
Posts: 151
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i found this one : here http://www.unitechelectronics.com/NE-555.htm A simple circuit to power a NEON lamp. Primarily used to test neons where safety is a requirement.
The R1 - R2 - C1 circuit determines the NE-555 to oscillate producing a voltage at Pin 3 driving
the small 8 ohm transformer's primary windings, the secondary windings are 1K ohms. It works.
This results in a ratio of 125 times gain, however we all know that's not going to fly. Losses ??
The theoretical voltage of 500 Volts AC passing through R3 10K dropping to around 180V AC
thus striking the gas within the neon and lighting it. This circuit was designed for pocket use.
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manis404
Posts: 32
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Is it possible to obtain like 400-422v with this system? I would use it to build a tube dual rectifier preamp - 4 12AX7s.
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Sometimes to do it right, you have to Do It Yourself.
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