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Luc and others:
I have read these comments about neon sign transformers allegedly being Ou many times before and let me respond to this.
For starters, I know very little about neon sign transformers per se. However, I know about transformers and I know that no matter how you cut it, a neon sign transformer is just a transformer. This reminds me a bit about the crazy debate I had on OU about ultracapacitors vs. "normal" capacitors.
The two important facts are that a neon sign transformer is just a transformer, and all transformers are under unity devices.
For the image that Luc uploaded, the neon sign transformer spec says 72 watts in and 152 watts out. (Input: 120 VAC, 06 amp, 60 Hz, Output: 5.1 KV rms, 30 ma rms)
So this appears to be over unity but this is impossible so what's going on here?
Here is where critical thinking has to come into play and follow-up research has to be done. I know that some people take these specs at face value and simply believe that neon sign transformers are over unity devices and they should get one on eBay and start playing with one.
(On a side note, these devices are probably the most dangerous things you could possibly play with and they could indeed kill you dead in a split second. I strongly advise everybody to stay away from these devices.)
Again, I will repeat that I know "nothing" about neon sign transformers, I have never even read a spec for one.
I am going to make the assumption that these specs are industry-specific. The specs mean something in the context of using the transformer in a neon sign application and are not to be literally used for a power-in vs. power-out calculation.
We know that a neon tube will do "burns" where the gas is ignited and becomes a plasma. The plasma will sustain a fixed voltage drop for a varying amount of current during one full cycle of the mains input sine wave. It is a completely non-linear load where conventional sine-wave style AC RMS output voltages and currents do not apply at all.
Therefore, the spec "30 ma rms" on the output side is most likely related to how amenable the neon sign transformer is to pulsing and sustaining a certain amount of rms current during plasma discharge "burn" cycles. These burn cycles must have a "start burn" angle and an "end burn" angle (relative to the sine wave reference timing) that is dependent on the length, pressure, and gas you are using in your neon tube. I don't know all the details and won't be looking them up. I will assume that if you exceed the spec for the rms discharge current then the transformer will get dangerously hot.
The bottom line is that the specs for a neon transformer are telling you about it's capacity to generate high voltage and sustain a burn inside a neon tube. These are industry-specific specs and you would have to do some real searching to understand all of the nuances. For sure, the specs are useful for their intended audience, the people that make neon signs.
Anyway, that's my thought process in action. I know ahead of time that it is absolutely impossible for a neon sign transformer to be an over unity device. I see that the specs look strange and appear to be over unity, and I say to myself that these must be industry-specific specs that are useful for the neon sign industry, and they are not generic transformer specs at all.
At this point for me it is case-closed, I am not going to do the digging past this point. I am satisfied that I am probably reasonably close in my assumptions. I don't even know if the "Don Smith Briefcase" makes use of a neon sign transformer, I haven't read this thread. The real moral to this posting is to not take things at face value when they go against what your common sense is telling you.
MileHigh
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Author
Topic: Don Smith's Briefcase Replication (Read 54374 times)
