Hey there,
I have one of these:
http://www.r-type.org/pdfs/6x5g.pdf
... along with a box of 200-something other vacuum tubes.
Don't ask me why I bought them. I think I was high and it seemed like a good idea at the time XD
Anyway, I wanted to use it to generate a large potential to get an electron beam a few feet in length. I figure that'll require somewhere around 50,000V in regular atmosphere (I forget the equation; I know it's inverse exponential distance to voltage but there's some constant). I could *probably* set something up to do it under vacuum or ionic gas, but I'd rather not.
Anyway, for some reason the pins labelled "NP" are missing.
Any idea how to hook this up to just use it as an amplifier? It says it can put out 1200V.
I have another Silvertone I can't identify. The only markings on it are 3-30 188-20, and is an 8-pin with pin 6 missing. I have another RCA 6-pole one labeled the same as the first, 3-35 (with no other markings) but from here: http://frank.pocnet.net/sheets3.html it looks like the datasheet: http://frank.pocnet.net/sheets/021/3/35.pdf looks different and won't give the same Vmax.
Another labelled 6SL7 GT I could find here: https://www.tubeworld.com/6sl7.htm ; ... but not much info. One from Japan 3254, all I could find is a V *drop* and a Hitachi I2DT8 that from here: http://www.datasheet.hk/download.php?id=1828961&pdfid=6EABBD324793B7AAE38B4C2F141ADA50&file=0416\12dt8_4809708.pdf doesn't look like it'll produce that much.
My questions are:
1.) Besides the anode and cathode, how are these supposed to be hooked up? Maybe I need to read more; I know nothing about tubes since I'm not that old =P
2.) I have a BOX full of these things. How can I find ones that will do what I'm trying to do and make an arc? Or do I need to get some other kind?
3.) What the f*** do all these numbers mean?
Here are some pics, of the loose ones I mentiones, a few out of the box and the box of (mostly RCA) ones I got.



edit: oh, and just to mention I *do* have several heavy-duty line transformers if this is a silly idea. I know I've seen it done with these before though. Maybe I have the wrong kind?
Thanks!
~ Ricky
-------------------- Any research paper or book for free (Avatar is Maxxy, a character by Mizzyam, RIP)
Edited by micro (04/05/15 05:43 AM)
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Well, where to start...let's begin with a safety warning: tube electronics generally operate at high DC voltages, which constitute a safety risk. Be very *very* careful when working with tube electronics, particularly because power supplies tend to include high voltage caps that take a long time to discharge. Even when disconnected from the grid, they retain their charge for a long time, so don't touch them without safely discharging all caps in the circuit.
Concerning the rectifier tubes: * Obviously they can't be used for amplification, since they are (double) diodes. They are intended for power supply rectification. * The missing pins are absent intentionally; NC or NP means that these pins don't have a function and they aren't connected internally. Often, they are physically absent. * Just to set the record straight: they don't provide a voltage; they just rectify an AC voltage.
In general: * Make sure to look up the maximum dissipation of a tube and stay below its limits. A tube can usually handle short moments of exceeding the maximum ratings, but they will burn out/short when they are run above their maximum capacity for longer than a few seconds. * Provide sufficient ventilation/cooling. Tubes dissipate a lot of heat in comparison with solid state electronics due to their heaters.
Concerning the triodes, pentodes and heptodes you apparently have: * The model numbers can generally be looked up to locate datasheets. The model numbers mean something, yes (they indicate what kind of tube you have), and other/additional numbers generally say something about manufacturing dates etc. Only the model number and brand are generally useful information, since they determine the ratings and operating characteristics. Note that the same model tube from different manufacturers can have different maximum ratings (max. plate voltage and dissipation, for example), while other operating characteristics are generally comparable between tubes of the same type from different manufacturers. * Triodes and pentodes can usually be used for low-frequency applications (such as audio amplifiers). Heptodes or triode/heptode combinations are generally intended for TV/FM tuners and have little use in an audio amplifier. You can find out what kind of tube and the intended applications by locating the data sheet for a tube. * For common tubes, reference or example circuits are often available. Many DIY-ers still use tubes for different purposes and usually you can find a circuit for a tube that at least gives you a starting point for electrical design, especially if you combine it with the data you get from the datasheet. You can also determine a tube's characteristics experimentally, but then it's a good idea to closely monitor if it doesn't overheat (signified usually by an anode that starts to glow - power off immediately if it does this!) and/or stay within the maximum specifications outlined in the data sheet. * Lots of information is available on the general operation of electron tubes. Generally speaking, an amplification tube (triodes, [beam] tetrodes, pentodes) operate in a similar fashion to a FET, with the grid acting in a comparable way to the gate in a FET and the cathode and anode correspond with the source and the drain respectively. Of course, tubes aren't plug-in replacements for FETs and vice versa, so this is just a theoretical comparison. In tetrodes and pentodes, the additional grids (g2 and g3) act as moderators for electrons passing from the cathode to the anode. Sometimes, beam tetrodes are driven using g2 instead of with g1.
About transformers (for audio): * 100V audio line transformers may be used as plate transformers in low-power, low-impedance audio applications, but the are extremely limited in terms of possibilities since they are usually not center-tapped and therefore cannot be used in push-pull architectures and core saturation will become a problem at very low power levels in single ended topoligies. * Dedicated output transformers for amplifiers are commercially available, but can be quite expensive. A pair of high-quality single ended transformers can easily set you back many hundreds of dollars. Lower end, low-power push-pull transformers can be had for under $100 for a pair. * A cheap alternative to an audio push-pull transformer is a center-tapped power transformer for 115/230V --> 6-15V. If the primary consists of two separate windings (115-0-115), it may be used in a PP-amp. High and low frequency response tend to be compromised, but this is also true for cheaper PP audio transformers, so they can be a realistic substitute. You'll need to do some calculus, experimentation and measurements to figure out if they are useful, but in my experience, a 115-0-115 to 12V transformer is in the ballpark for a simple push-pull pentode amp using e.g. a pair of EL84's or EL34's/6L6. Impedance matching is not a very exact science; a bad impedance match will influence the frequency response and output power, but the end result can be very usable.
I have no experience with making arcs, but I would be very cautious indeed as you generally work with voltages in excess of 1kV, which, combined with the capacitance usually involved in these circuits, is lethal. If you're new to tube electronics, try a low-powered audio amp with a plate voltage around 175V-200V and limited power supply filtration first. Everyone I know who has done anything with tube electronics has been zapped at least once and usually many times and it's an experience that is best not repeated and potentially lethal if you work with higher voltages. Note that high voltage DC is particularly risky since it causes your muscles to contract, so once you make contact, it may not be physically possible to let go since your muscles cannot relax, continuing your electrocution. This is different from putting your fingers into a wall socket, as that's AC.
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To add some more info on tubes, from memory (along time ago) the first number, 6 or 12, is the voltage required by the filament. You will need the corresponding correct socket for the tube(s) you use, a chassis (usually metal) for the sockets with holes cut or punched for the sockets. I don't remember much on circuit design as tech school was 45 years ago! Tubes can be used to make gates as well as amps; and, nand, nors, ect.
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Thanks!
Yeah, I have safety in mind, not near me or anything grounded, etc. (form a barrier using the forumla for distance given V and add a bit).
I know they were used in place of transistors but I have been using transistors since I was like.. 5,6,7?
Anyway, thanks a bunch! That gives me a starting point.
I think I could do it with a graphite and mercury anode/cathode.
(or graphite and 50% of graphite 1)
-------------------- Any research paper or book for free (Avatar is Maxxy, a character by Mizzyam, RIP)
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