I like the Lorenz Attractor. It looks like a nice rainy-day project. However, fair warning: the MPY634 is a wee bit pricey at ~$20.00 in small qtys. However, if you save for a while and dig really deep, this is available from TI via Mouser (and others?) for $119 - about the cost of the ICs:
http://www.mouser.com/Search/ProductDet ... MIKROE-957

The manual tells more:
http://www.mikroe.com/downloads/get/174 ... manual.pdf

With a little imagination, it is a BIG step up from the Heathkit or RS 300-in-one project kits of my youth. I think maybe Santa Clause has one with my name on it!
- Jeremy

Thank you for that Jeremy. I know TI has some really nice dev kits but that's one I've not looked at before that would be a lot of fun!! In a clear case, on display too!! I could put a fiver in a sock and save up for it, may not come for this Christmas for me LOL but soon enough. And yes those MPY634 @_@ are pricey its why they are on the "I will get" list rather than the "got" list.

Many fractal maths are fairly straight up "make point, display point" and those sets would do fine with using op-amps as maths elements. Displaying in a 'human friendly' manner is where it can get tricky. There are versions of the op-amp Lorenz that will output fast enough that the owl eyes show nice, but that can also be helped by using a crt with long decay phosphor. Escape time fractal sets like the Mandelbrot present their own issues though http://mathworld.wolfram.com/MandelbrotSet.html and would be a challenge to make from electronic parts but I think it is doable.

You don't need that transformer. You can use an ordinary table radio power transformer and whatever filament transformers are needed to get the required voltage rating for the CRT and anything else that runs at high voltage (there usually isn't anything else). While these transformers are expensive if you buy them new, used ones are perfectly fine. Go to hamfests and antique radio swap meets and look in the boxes under the tables.

If you Google "charge pump" you won't find much. Use "Cockroft-Walton voltage multiplier" instead.

The CRT is rarely the limitation on bandwidth untll you get up into the 10s of MHz. The amplifiers are the limiting factor.

Jim Mueller

Rich I have seen doublers used in some CFL circuits on the larger end. Not in the consumer screw in ones. Used as part of the voltage in, double to 240v then on with SMP goodness. There are also a few (only a few) homebrew CFL circuits around too (and general 'light a florescent easy' circuits) that make use of doublers too in the same manner, moving the input voltage up. Nope, the very last thing on a CFL's mind is clean power and being RFI friendly!

Bob!! 68uF is lower than what I have seen used and made a mental note of values (easier to see 10 things and remember a range than the ten individual things). I've seen 220uF, 330uF and 470uF used in essentially that same set up.

Jim that I think I have read on, "Cockroft-Walton voltage multiplier". There was a fair bit I did read, and I did do the numbers by hand a few times. Which is how I compared that Falstad java applet and what the app does and what the maths suggested were pretty much the same.

I remember a conversation here some years ago on servicing radios that for AM at least 25mhz was needed, and 35mhz was better. I recall part of the conversation was on the development of oscilloscopes and included design methods and that one of the barriers to a scope was also construction methods, that tag board designs were part of that limitation. But, that was a good many years ago now and I may be mis-remembering that. Been on ARF since I think 2001 or so time flies by. [yup: Posted: 04 Jul 2001 19:19, that was a few years ago now lmao]

I do know there is a surplus shop I've not been to that should take if I recall the last time I thought of it, five city buses across four cities to get to (somewhere between 3 and 5 hours time there on the bus) I will have to get to. The other surplus shop that is only a train ride to doesn't have a good selection of transformers sadly I kick myself they had some toroid transformers put out 62.3v@10a for 20 bucks each that would have come in handy. But the last few times there they only had a few 5V to 12v wallwarts and nothing higher. Well summer road trips are always fun no matter

Analog multiplier chips tend to be expensive, but there are cheaper ones available than the MPY634. The venerable XR-2208 is still available for $6.29 here:
http://www.abra-electronics.com/products/XR2208.html

Go to hamfests and antique radio swap meets and look in the boxes under the tables.

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Can someone volunteer to look for him at upcoming Kutztown?

Thanks for the heads up on this Bob. That company has a 50 minimum order and does postage on the fly I will look for that from another supply unless I come up with a bunch of funds all at once for them I do have a strong desire to purchase the Raspberry Pi though (I took Python programming and my son is taking Python next school year) and they have some nice Pi kits there so maybe it could become part of next years school budget (:P Life on a budget eh YAY).



HAHA Thank you Bill. Trouble isn't finding for a decent price through ARF. The cost of shipping a transformer here is painful at best (and even here to here, Canada Post is terrible for price. Think of the size of a standard Guitar Pedal and that from Montreal to Toronto costs over 20 to mail here). http://www.antekinc.com/transformers/ is a pretty solid company with a decent power transformer line (and they managed to recover from their fire that nearly wiped them out), their shipping north of the boarder hurts of course. There are a few other companies with good base prices like https://www.edcorusa.com/ but as soon as you tack on their shipping well (and edcore makes square transformers, whereas the toroids are more flat, the squares cost double shipping over the flat) In the end yes, I may just lump the 57 dollars (well, 35 for the antek 100va 250v transformer http://www.antekinc.com/as-1t250/ , and 22 shipping and the trouble of requesting they make it ... they have recovered from the fire but they still have not a full product line in stock) but before then I have 12v transformers and diodes and capacitors and figure 'why not try with what I have'?

On another tak can units like the one described be used for CRT tubes such as the 2BP1 nominal 1.5kV?

The 2BP1 will run, on Anode 2, with anything from 500V to 2KV (2.5KV absolute max):
http://frank.pocnet.net/sheets/049/2/2BP1.pdf
1000V is a typical operating point. Is that 1000V isolated ? Remember you want a -1000V. If its isolated, then that can be easily achieved. Also the filament needs its own 6.3V winding. You can't share it with the other 6V filament tubes.

When I once worked in a former high-voltage switching power supply design position, we built them to several kV. They were potted and they ran at high frequency (10s of kHz). None of these were built for high current loads. The supplies built for high current loads were typically made using a transformer, either multi-winding or auto-transformer.

Well what I have "on hand" is a cluster of printer transformers with around 16 to 35 volt secondariness. I have also maybe 10 or so 12.6v 1amp filament transformers that had been "realistic" branded sold though Liquidation World. That is about it. I know from some few years ago (back before Curt passed away) no one here backed the idea of running two primaries in parallel, and two secondaries in series to two secondaries in series to two primaries in series to go 'up' from 120 to 240. Actually seemed to have caused a fracas when I asked that so I gave up on that as a means of gaining HV of any kind. Filed for future pursuit this idea of using doublers instead.

When I get the CRT's (and the two I do have already) in the mail and wired for sound yes the filaments will have their own supply and have protection too. CRT's have in many cases gone up considerably in cost the past 10 years and considerably down in availability so when I get my nuts n bolts together I wont be taking big chances with them.

And the worst shock of my life was 1600 volts (I measured it after the fact to find out how much a bite I took) that threw me 10 feet through the air (gotta love spasmodic muscle reactions) when I was 10 or 11. I lived, but man did I hurt for a long time. Nothing says learnin like a little burnin! I learned a VERY deep respect that day. I have an isolation transformer (somewhere here) though I'm not sure how good it is, it is 120v:120v at 1 amp. I don't think I'd be building 120 watt devices so I am hoping it will be good enough.

I do have to say, it was a lot easier to hobby with this in the 1970's. I had my grandfather to help me back then, and parts were a lot more available back then, I didn't have the arthritis that hit me at 33 and I wasn't prone to the grey moments like I am now.

And the worst shock of my life was 1600 volts (I measured it after the fact to find out how much a bite I took) that threw me 10 feet through the air (gotta love spasmodic muscle reactions) when I was 10 or 11.
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Mine was off the old tv's in the trash in the early 50's. If you didn't go chassis ground to the top of the HV tube in the cage with a screwdriver to discharge things. Pulling that only big lead to the picture tube could getcha! It felt like 1600 but was likely far less. I never moved 10' either but rather just down and out. Purpose of grabing and stashing those long skinny chassis was for spare parts or homebrewing.

That looks amazingly similar to the Min-O-Scope from Popular Electronics, August 1960. Even the part numbers match.