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Author Topic: Tubes?  (Read 191850 times)

Offline Super God

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Tubes?
« on: July 19, 2007, 12:46:18 AM »
SM said transistors were far too noisy to use for prototyping, so I figured, "let's use tubes, he did say to use them, right?".  But, I don't know the first thing about electron tubes!!  I've never seen one, let alone use one.  Right now I'm looking on TubeDepot.com for some tubes, and I don't know what I'm looking for.  Ugh, frustrating!  Anyone with some tube experience here?  I could really use some help!  Thanks!!
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Offline tao

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Re: Tubes?
« Reply #1 on: July 19, 2007, 12:49:23 AM »
Quote from: Super God on July 19, 2007, 12:46:18 AM
SM said transistors were far too noisy to use for prototyping, so I figured, "let's use tubes, he did say to use them, right?".  But, I don't know the first thing about electron tubes!!  I've never seen one, let alone use one.  Right now I'm looking on TubeDepot.com for some tubes, and I don't know what I'm looking for.  Ugh, frustrating!  Anyone with some tube experience here?  I could really use some help!  Thanks!!

I think that the majority of people here don't know how to use them either, you are not alone................... 

;)
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Offline Super God

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Re: Tubes?
« Reply #2 on: July 19, 2007, 12:50:56 AM »
They cost an arm and a leg too, jeez 44.95$ for a tube...wow :o
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Offline Super God

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Re: Tubes?
« Reply #3 on: July 19, 2007, 01:21:25 AM »
The 12AT7 looks good for my design, I can use either 6 volts or 12 volts for the heater, I think I'm going with 12 for now.  It seems weird using a transistor to switch a tube on and off rapidly.  Oh well, in SM we trust :D  Heh.  I hope these tubes work well.
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Offline nutekk

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Re: Tubes?
« Reply #4 on: July 19, 2007, 01:34:39 AM »
wouldnt you want to be making a tube oscillator circuit
maybe a VCO ?
i guess you would need 3 of them.
look for some micro-tubes.
they will be small enough to fit in the center of the ring.
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Offline Super God

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Re: Tubes?
« Reply #5 on: July 19, 2007, 01:40:19 AM »
Yeah, this one is a dual triode so I figure 5 should be good for mine, I have nine controls instead of three.  So 1 tube for every 2 controls seems good.
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Offline Super God

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Re: Tubes?
« Reply #6 on: July 19, 2007, 01:41:05 AM »
Wait, how much voltage to you need to pulse the tube with in order to make it conduct?
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Offline innovation_station

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Re: Tubes?
« Reply #7 on: July 19, 2007, 02:21:42 AM »
hello all

in 1 of my last posts i said i was going to use tubes hummmmm


how am i going to use them  well i thought a tube freq generator and a tube amp has anyone seen the video from border land sciences i posted a link a while ago wich i saw in another thred it is how i would start using tubes in a tpu type setup i will look for the link and post it when i find it


ist
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Offline BEP

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Re: Tubes?
« Reply #8 on: July 19, 2007, 05:17:47 AM »
It would be agood idea to look up tube theory for those who don't know it.

They are virtually the same in function as transistors. There are some very useful differences.

Diodes/rectifiers use the same charts except they will conduct almost any current you apply at almost any level. There is a turn-on point but it can be extremely low. There is a reverse current stoppage also but in both cases there is virtually no wishy-washy turning off and on points
(noise/harmonic generation). You want fast - you got it! Think check vavle.

Gated tubes - triodes and other extensions with grids are analogous to water valves with knobs or transistors.

Basically a tube diode has a cathode and a plate (all have heaters). Think of the plate as the banded end of a 1n2004 and the cathode as the unbanded end.

A triode is the same as the diode but it also has a grid. Think of the grid as the base of a transistor, the cathode as the emitter and the plate as the collector. Tubes require little or no feedback to trigger the input - depends on circuit.

Tetrodes, pentodes, beam tubes, etc, etc, are all variations of the above.

The main difference is that on a SS circuit light comming from your board is a very bad thing. Light comming from a tube circuit is a good thing. There are limits in light and all the other things just like SS.

Another difference is that they are all mini-particle accelerators! If you want to use them as fast switches go for VHF/UHF class tubes. On there turn-on point they are simply ON.

I feel sorry for those who haven't used them. You think you've made smoke? No way! I've burned things down with them!

SM was completely right when he said something like start with tubes to figure it out - why? Because there are fewer extremely fine details to consider during design and they will only conduct what they are capable of. SS blows up instead. Fewer supporting parts also, when done right.

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Offline Super God

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Re: Tubes?
« Reply #9 on: July 19, 2007, 05:37:29 AM »
So if I applied a 12 volt DC current to the grid pin it would start conducting over the anode and cathode?  No resistor like a transistor would need?  If so then yeehaw.  I found one that looks good, it was designed for VHF/UHF!  So, I may have an easy time finding the right frequencies!  Yay.  It's two in one, too :)

Thanks!
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Offline Super God

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Re: Tubes?
« Reply #10 on: July 19, 2007, 05:40:30 AM »
Tubes may be my new best friend!  Nothing to blow out or anything like that, and they aren't small enough for me to lose like a transistor.  Sweet.  Fast on and off times?  YES!  I need super fast nano second on and off times :D  I need KICKs!  Weee.
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Offline innovation_station

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Re: Tubes?
« Reply #11 on: July 19, 2007, 05:49:13 AM »
here is the link i spoke of earlyer

http://video.google.ca/videoplay?docid=-721789270445596549

if you watch this i think it is a big part of the tpu and how it works using tubes

ist
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Offline innovation_station

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Re: Tubes?
« Reply #12 on: July 20, 2007, 06:50:31 AM »
doing some more reading and i found thease are the tubes steven says he is using


6BQ7-A tubes

and they seam to be quite common and cheep  also who has worked with a phase invertor seams to be a big part of the tpu


ist
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Offline BEP

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Re: Tubes?
« Reply #13 on: July 20, 2007, 07:48:16 AM »
I agree on the tubes.

Anyone who does not understand the importance of magnetics or longitudinal waves absolutely MUST view this video.

Thanks innovation_station!  

This is the most applicable information I have seen ANYWHERE.
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turbo

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Re: Tubes?
« Reply #14 on: July 20, 2007, 07:56:42 AM »
Lee De Forest
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