10uA*25kV = 0.25W -- How small a TV screen are you watching? Large CRTs at moderately high intensity use considerably more than that. My impression is that the HV current is around a milliamp, though I have to admit it's been quite a while since I put a meter in the HV line of one.
Cheers, Tom.
This may be of interest :
On 8 Nov 2006 00:45:31 -0800, "booth" Gave us:
A TV flyback is NOT going to give you a 30kV cap charger.
Yes, you DO need to buy one custom from a supply maker, and have THEM build them. A 30kV supply has MANY special considerations to deal with from a manufacturing viewpoint. One doesn't simply declare that one is going to start manufacturing high voltage power supplies. It is a bit more complicated than that.
Your 300W cap charger is no "build it from scratch" deal.
Even a 1kV 1kW charger is not easy.
Try a reputable high voltage supply maker and rest easy knowing you got what you paid for. Trying a project this size and complexity in house will cost you far more.
By the way, what capacitor bank that you know of charges at 10 mA rate?
I think you need to also sit down and do a requirements analysis.
How many cycles of charge per minute do you expect to see, and on what size capacitor bank?
Try these guys.
On a sunny day (Thu, 09 Nov 2006 04:57:29 GMT) it happened joseph2k wrote in :
Sorry to have to correct this, the current in a color tube is about 1.5mA max, say .5 mA per gun, at 25kV.
1.5 mA at 25 kV = 37.5 W, peak more. hard to find in a few moments on the internet, but here is a hint:So you would need 7 in parallel, and boosted up to 30kV (should work)..... But no guarantees it won't flash over and / or kill the multiplier. You can make your own HV cascade too. Winding the transformer is a bit more difficult for the HV coil, easy for the primary. Then use a bigger core and one of course.
On a sunny day (Thu, 09 Nov 2006 09:53:20 GMT) it happened Mike Harrison wrote in :
Wow :-)
On 8 Nov 2006 22:58:47 -0800, "Tom Bruhns" Gave us:
Large TVs (with large CRTs in them) don't even use 300W at the outlet so I hardly think that they are burning all they do use up in their anode supplies. Try again.
Bio capacitor charger maybe
martin
Nope. Guess again.
Several kilowatts are usually involved in the horizontal scan of a large screen tv. A special switching circuit first fills the deflection coil with positive current for the right half of the sweep, resonates it for a half cycle on retrace, and then returns the energy as a negative deflection coil current for the left half of the sweep.
The energy is borrowed and returned to the power supply storage capacitors. Only the small coil losses need be provided by the power line. And nobody notices the few initial scans needed to get up to speed.
This is an extremely elegant energy efficiency conservation scheme that has been in use for many decades. I first described it in a 1965 story.
one: (928)428-4073
I think you mean KVA not KW Don.
On a sunny day (Thu, 09 Nov 2006 08:05:29 -0700) it happened Don Lancaster wrote in :
I think you are terribly confused on the subject.
Confused since 1965.
I think you're thinking of an oscilloscope, where the beam currents are very low, as you are only painting one line, and with a high-efficiency phosphor, and no shadow mask.
In a TV-set type of CRT, the poor beam has to scan the whole screen, and on a color set, a lot of the current ends up caught by the shadow mask. A milliamp or two is more like it.
Projection CRT's use even higher current-- that's why they need liquid cooling and heat sinks.
Don's talking about the circulating currents in the yoke. The poor original poster was talking about the CRT HV supply. Two different animals.
Don's right-- there's a lot of voltage and current in the yoke circuit-- upwards of ten amps, and high voltage on the retrace-- many hundreds of volts. Luckily it's not both at once, so the real power is much lower.
On a sunny day (9 Nov 2006 08:50:48 -0800) it happened "Ancient_Hacker" wrote in :
Yes, was it you who mentioned VA? For a typical BW tube with 110 degrees deflection I remember the current something like 10A peak. But _WATTS_ requires a resistive component, the resistance of the defection coil is where the power loss is. And _that_ power is of course never 'returned'.
Exactly, Don was wrong.
Arithmetic checking time?? 1mA*25kV = 25W. Modern large CRT displays draw considerably more than that from the mains. A few watts are required to drive the vertical deflection and video output stages. A pretty big percentage of the total power goes into driving the horizontal sweep and the second anode, which of course (generally) all goes through one transformer. (I used to have a monitor that used a HV supply that was independent of the horizontal sweep, but that's pretty rare.)
Cheers, Tom
Well, a carefully designed and wound 60 cycle transformer could do this, perhaps with a doubler or tripler on the output side. The secondary would have to be wound pi style to handle the potentials involved.
What do the commercial units use?
On Thu, 09 Nov 2006 08:05:29 -0700, Don Lancaster Gave us:
That's ridiculous. How could you make such a blatant error, Don?
A wall outlet only provides a maximum of 1.2 kW, and that is on a very good day.
A TV that only consumes 350W AC Power going in does NOT produce "several kilowatts" anywhere internally.
Are you sure that you studied electronics or electrical engineering?
Power out is ALWAYS less than power in. The power supplies and circuitry in a 350W TV can consume no more than a total of 350W throughout its entire circuit. That's just the way it is.
Now, I made a pretty mean triple anode supply for a three gun projector for commercial aircraft once... But that was a different time.
You should re-examine your understanding of this/these issues.
On Thu, 09 Nov 2006 08:05:29 -0700, Don Lancaster Gave us:
It STILL is NOT kilowatts!
On Thu, 09 Nov 2006 08:05:29 -0700, Don Lancaster Gave us:
Yada yada yada... you still got the power wrong.
Even your "stored energy" calculations are miles off.
Power is power. It doesn't just appear from thin air.
On 9 Nov 2006 07:17:03 -0800, snipped-for-privacy@aol.com Gave us:
Still incorrect.
On 9 Nov 2006 08:50:48 -0800, "Ancient_Hacker" Gave us:
No s*it.
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