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Nicko

Tue May 25 2010, 05:52PM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

DaJJHman wrote ...

I planned a while back to just harvest parts from a giant oscilloscope I picked up at a hamfest, even though it has better specs I think than my much smaller one it takes a lot of space for what I thought was a primitive high end transistor unit... I was stupid to think so. It turns out, the thing is entirely Tube based and I can never turn down something based on tubes! I might clean up the inside, and make some Acrylic walls and make it into a table or something, where I can still use it but it looks nicer.

pics of the guts:...

The real and genuine tragedy about old tube-based Tek scopes is that some saddo so-called audio enthusiasts are buying them up and stripping them for the tubes & junking the rest. Yes, they don;t care, but some of these scopes are really rare. Over on the Tekscopes Yahoo! forum there's been loads of grumbling about this...

Sigh...

quicksilver

Wed May 26 2010, 04:08PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Got this HV power supply from Surplus Sales of Nebraska. It's a DUEL 11K supply designed for a plasma display. I can draw a 4cm arc from each....and they give you the schematic. I was told there was no obvious way to set them up in series

This actually the 1st time I've sen a LOPT being used in this manner.
However if anyone has seen them before and knows a bit about it I'd love to hear what you know. The design is very intriguing.

IntraWinding

Wed May 26 2010, 04:50PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Can you post the schematic?

quicksilver

Wed May 26 2010, 05:08PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I will do my best. I need to scan it and sharpen the image as it's poorly printed. It runs very cold. This may be not only because of the huge heat sinks but they (LOPT's) are not driven very hot but head into a voltage multiplier (black boxes). It's a neat little supply.

quicksilver

Wed May 26 2010, 06:08PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

I put up the Photo-Shopped .gif at 600dpi
If you learn anything that may be helpful, please let me know. I have many of the parts needed to make my own. I know I have two new AC LOPT's but the IC is what takes me back. It has a single Lg IC that appears to be a controller of some type. For me, it wouldn't be a light-weight project!

What I know about it is this:

It was designed as a DUEL 11k supply for a plasma sign. I don't know if drawing arcs is what it's made for; so I put a 100K 3W resistor on the ground wire prior to drawing an arc. I got a some good one about 4cm. The protection is supplied by one fuse but that seems to protect the AC input. There appears not to be anything to keep it protected on the individual units. But putting it into a plasma screen would sustain a given voltage: correct? So drawing an arc shouldn't be a big deal.
The "black box" voltage multipliers are made very well. The whole thing was produced in Japan for a sign mfg company.

quicksilver

Wed May 26 2010, 06:10PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

11k schematic

1274897434 1408 FT6000 Schematic 11k Ssn Copy

Dr. Drone

Wed May 26 2010, 06:58PM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Chris Russell

Wed May 26 2010, 07:21PM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

Dr. Spark wrote ...

Keep close to W.W.T 2011 and bring some extra underwear indeed! (bring any old tools you want to melt)

2011 is the year I'll finally be able to attend! Looks like a lot of fun is planned.

Steve Conner

Thu May 27 2010, 07:49AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

It wouldn't surprise me if the chip in that high voltage power supply were a TL494 clone. Does the pinout make sense for a TL494, and does the part number end in "94"?

Probably, you can't use the outputs in series because they're both the same polarity and both referred to ground.

Also, nice tube Dr. Spark

quicksilver

Thu May 27 2010, 02:45PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Steve McConner wrote ...

It wouldn't surprise me if the chip in that high voltage power supply were a TL494 clone. Does the pinout make sense for a TL494, and does the part number end in "94"?

Probably, you can't use the outputs in series because they're both the same polarity and both referred to ground.

Also, nice tube Dr. Spark

Yep: they use that topology. It's a pity because I got the little guy with the idea of grabbing 22k.

edit* - I mistyped the thing...sorry. I answered my own question.....But is there anyway to determine if this design is robust enough to continually draw arcs and generally experiment with? I put a 3w resister at ground to simply test it's functionality but i don't know if plasma sign PSU's are made with little slack for shorts or overvoltage.

-=-=-=-=-=-=-=-=-=-=-=-=-
For those who don't live here....We grow those tubes in Arizona. They can be seen from the highway. If you ride a motorcycle you can stop and check them out up close. The older ones have more "arms" coming out.....

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