Yes, use a converter to get high voltage. I am sure you can find a 12VDC to 110VAC converter plug into the cigarette lighter socket.Then you start for there. Be careful on the current limit of the lighter socket.
This is just one example, I am not by any means endorsing this:http://www.amazon.com/BESTEK%C2%AE-outlets-inverter-notebook-MRI3011BU/dp/B004MDXS0U/ref=sr_1_1?s=automotive&ie=UTF8&qid=1418883806&sr=1-1&keywords=12v+to+110v+converter
This is just one example, I am not by any means endorsing this:http://www.amazon.com/BESTEK%C2%AE-outlets-inverter-notebook-MRI3011BU/dp/B004MDXS0U/ref=sr_1_1?s=automotive&ie=UTF8&qid=1418883806&sr=1-1&keywords=12v+to+110v+converter
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Go to TubeCad.com. John Broskie offers a low voltage Aikido board.
New Aikido 12Vac PCB and part kits
The Aikido preamps are the cat's pajamas.
New Aikido 12Vac PCB and part kits
The Aikido preamps are the cat's pajamas.
I have seen tube guitar pedal and some design using 12V. The input impedance becomes very low. People need to have transistor to drive it for guitar. Also, the voltage swing is very small, that leads me to think the distortion will be quite high.
Why even want to design LV tube preamp? Why even want to re-invent the wheel of a 12V to 110V converter. You can buy off the shelf converter like the one I put the link in post #2. Then spend the effort to design a nice preamp using 110VAC that you can use at home or in the car!!!
Why even want to design LV tube preamp? Why even want to re-invent the wheel of a 12V to 110V converter. You can buy off the shelf converter like the one I put the link in post #2. Then spend the effort to design a nice preamp using 110VAC that you can use at home or in the car!!!
Yes it is, but the available signal level is just some 1.5 Vrms max.
I studied these circuits once and according to my notes the attached circuit worked well.
This kind of circuit needs to be adjusted individually to proper operating point.
There is 1M trimmer resistor at the gate of the 1st tube.
Adjust the cathode voltage of the 2nd tube to 6 V with this trimmer.
That's all the tuning it requires.
The load should be a 50 k volume potentiometer, not smaller.
The signal source should be have low output impedance, but this is not a problem, because today most equipment has.
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You could use a nixie driver board..
Or have a go at a converter..one of the problems with a battery is the cathode heater voltage difference.
I use a DC to DC converter to isolate the heaters from the DC supply so an Aikido might not be the way to go..YMMV
If you were using low voltage AC you could transform..however your using a battery..the other way is to use a chopper circuit..
(Like the old car radios)
I built a project for fun using only DC as an input..
http://www.diyaudio.com/forums/tubes-valves/177844-strip-board-project-completed.html
Regards
M. Gregg
Or have a go at a converter..one of the problems with a battery is the cathode heater voltage difference.
I use a DC to DC converter to isolate the heaters from the DC supply so an Aikido might not be the way to go..YMMV
If you were using low voltage AC you could transform..however your using a battery..the other way is to use a chopper circuit..
(Like the old car radios)
I built a project for fun using only DC as an input..
http://www.diyaudio.com/forums/tubes-valves/177844-strip-board-project-completed.html
Regards
M. Gregg
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You can build a tube preamp that will work very well with only 12V HT. In the very early days of transistors, they could only make low frequency transistors cheaply. So car radios went through a transition period, when they were hybrids - part tube and part transistor.
Classic tube car radios used a vibrator - a sort of self oscillating relay to chop up the 12V DC into AC, which was stepped up by transformer to 250V AC for HT. The vibrators, as they had moving contact points, were fault prone. When the early germanium power transistors were developed, but before cheap RF transistors were possible, car radios were made with a transistor audio amp and transistor power output stage, and no vibrator or 12 to 250V transformer. A special line of RF vacuum tubes were developed designed to work with 12 V on the anodes. A special "space charge" grid was included between the cathode and the control grid, to pre-accelerate electrons before the control grid, so a reasonable anode current was drawn with only 12V available. The space charge grid was internally strapped to the screen grid. 12V HT audio "triodes" were made as well - they are actually tetrodes because of the space charge grid.
You can still find these car radio tubes on ebay. Types include 12AD6, 12CX6, 12AF6. etc. There was quite a range of them. Google "12V car radio tubes" and you'll get sites that list the type numbers and data. Gm with these tubes on 12V HT is much the same as for normal tubes on 200 V HT, but the anode impedances are much lower. You could even make a power amp with 12V HT, but as no tubes were designed to be power output tubes on 12V, you'll need an awful lot of tubes in parallel just to get a 100 mW or so of audio.
For an audio preamp, choose 12V HT car radio sharp cutoff pentodes or "triodes" to taste, and use a completely conventional circuit, but with 12 V HT. Most of these 12V car radio tubes have a maximum screen and anode voltage rating of 30V. Some were rated at 16V max. If you make a small power amp, they'll produce a lot more power on 30V than on 12V.
Incidentally, before transistors, most electronics manufactuers of note made portable public address amplifiers designed to run off a 12V car battery. These used conventional tubes with teh 250 V HT generated by means of one or two car radio vibrators. You can stiil, find these vibrators on ebay too. These amp were limitted to 5 W output if one vibrator, used, 10W if two vibrators used, or about 20 to 25 W if two vibrators were used with a Class B push pull output stage.
Classic tube car radios used a vibrator - a sort of self oscillating relay to chop up the 12V DC into AC, which was stepped up by transformer to 250V AC for HT. The vibrators, as they had moving contact points, were fault prone. When the early germanium power transistors were developed, but before cheap RF transistors were possible, car radios were made with a transistor audio amp and transistor power output stage, and no vibrator or 12 to 250V transformer. A special line of RF vacuum tubes were developed designed to work with 12 V on the anodes. A special "space charge" grid was included between the cathode and the control grid, to pre-accelerate electrons before the control grid, so a reasonable anode current was drawn with only 12V available. The space charge grid was internally strapped to the screen grid. 12V HT audio "triodes" were made as well - they are actually tetrodes because of the space charge grid.
You can still find these car radio tubes on ebay. Types include 12AD6, 12CX6, 12AF6. etc. There was quite a range of them. Google "12V car radio tubes" and you'll get sites that list the type numbers and data. Gm with these tubes on 12V HT is much the same as for normal tubes on 200 V HT, but the anode impedances are much lower. You could even make a power amp with 12V HT, but as no tubes were designed to be power output tubes on 12V, you'll need an awful lot of tubes in parallel just to get a 100 mW or so of audio.
For an audio preamp, choose 12V HT car radio sharp cutoff pentodes or "triodes" to taste, and use a completely conventional circuit, but with 12 V HT. Most of these 12V car radio tubes have a maximum screen and anode voltage rating of 30V. Some were rated at 16V max. If you make a small power amp, they'll produce a lot more power on 30V than on 12V.
Incidentally, before transistors, most electronics manufactuers of note made portable public address amplifiers designed to run off a 12V car battery. These used conventional tubes with teh 250 V HT generated by means of one or two car radio vibrators. You can stiil, find these vibrators on ebay too. These amp were limitted to 5 W output if one vibrator, used, 10W if two vibrators used, or about 20 to 25 W if two vibrators were used with a Class B push pull output stage.
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This is a false assumption.
You can use many typical triodes such as ECC82, ECC88, ECC81 etc. with 12 V supply voltage, but with the limited signal level and low input impedance (some k-ohms) due to grid current required to drive the tube .
This requires that the tube must be biased with positive grid voltage to proper operating point.
During my tests I achieved 1 Vrms output level with 0.3 % THD at best.
Ofcourse the vacuum tubes are not designed for such low +Ub, but they work.
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