• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Magic Eye spectrum analyzer

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I built the 555 supply they had. The boost converter.


It worked nicely with that tube radio. the inductor did get quite warm.

it ran about 114v open circuit, and 94 with the radio on.

This is from 5volts. I havent tried 12 yet. GOD. need to build the regulated one.

For the hell of it, I change the frequency around a bit, the inductor got soo hot, it melted it and shorted the windings. LOL. Thats the fun part of electronics I love.
 
mbates14 said:
I built the 555 supply they had. The boost converter.


It worked nicely with that tube radio. the inductor did get quite warm.

it ran about 114v open circuit, and 94 with the radio on.

This is from 5volts. I havent tried 12 yet. GOD. need to build the regulated one.

For the hell of it, I change the frequency around a bit, the inductor got soo hot, it melted it and shorted the windings. LOL. Thats the fun part of electronics I love.

This is a design from a guy on the NEONIXIE-L forum - it's not mine, but an example of a 555 design that is regulated and does work.

HTH,

Nick
 

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I didnt see any strickly transistor designs, for the hell of it, I may try and make one. I do those things quite often. Thats how I made my Diy electric lawnmower. hehe.

But anyway, I replaced the inductor with another one from my parts bin, its 22 Milihenries, way to high I know, but it ran cool. and ran the tube radio no sweat. the voltage maxed out at 65. (perfect for tube radio). So I may make one for this project, and one for my tube radio!!

I need to drop the inductance to obtain a higher voltage? not sure how the inductance plays a role in this circuit, although I know it does! just dont know the theory behind it.
 
mbates14 said:
I used an IRF510. It works with it, although, I dont know if it has a low enough RDS and if it can handle the voltages its dealing with, but in a 20 minute run, it worked fine. Also got a 541, havent tried it.

Do some basic research - the IRF510 is only a 100V device - it WILL fail. Type in IRF510 to Google, and read the datasheet.

I think we've told you all we can. You need to do some basic learning on this - I've given you a tried and tested design - your inductor is WAY too high to maintain 250VDC out - you need something between 100uH and 220uH @ 1A otherwise the SMPS will not store enough charge quickly enough to maintain the output voltage.
 
AlekZ said:
My spectrum analyzer with EM84 tubes:

http://www.edw.com.pl/ea/analizator.html

Unfortunatelly in polish language, but I think that the schematic diagram is clear:)


could you explain that circuit, how it works in english? like the filters/drivers and stuff. because i want to do a 5 frequency, not a 4 frequency.

i tried a polish translator and it aint worth a crap. none of them are out on the web.
 
As the block diagram shows, mix (sum) the signals, filter into 4 or 5 bands, (and stick through an amplifying stage with enough gain to drive the magic-eyes), and hey presto!
You could use op-amps (or transistors) in place of the triodes, especially considering you don't have much power to play with. In fact, I think the entire schematic could be redrawn (or redesigned) to use only common components - Op-amps, Resistors and Caps.

Now, some guesswork as I can't read Polish :D

I guess the two inputs 'L' and 'P' are Polish Left and Right, which means V1 is just mixing the two signals together.

Next guess, it looks to me like a series of CR (i.e. high pass) filters before the next triode sections, with low filters (high in the case of the last band) between triodes. At least I think so... those CC potential dividers are confusing me a bit.
The triodes I assume are there to get the signal into the right range for the EM800s (0V to about -8V, if you use the built in triode section), and provide buffering between filters.

So to make it 4 filter not 5 filter, you'd drop off one of the filter sections and adjust the CR/CC/RC filters to get the right frequency notches you want.
Use the formula f-3dB = 1/(2*pi*C*R) to find the filter corner frequency (I believe this is the right term). If it's high pass, frequencies > f-3dB will not be attenuated, the inverse being true for low pass. If you start off with the value of one component, the corresponding value to complete the filter can be calculated using x = 1/(2*pi*Value*f-3dB (Desired)).

HTH, and hope I'm not totally wrong :p
 
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