Hey someone who hasn't been awake since for 16 hours double check me please:
This says it runs at 110 - 240 volts, 50 hz, right?
Which means I'll need a power transformer to take me from 60 hz to 50 hz, but I won't actually need to change the supplied voltage from US single phase power?
Does that make sense? I feel like it doesn't, but i can't figure out why.
which has a bunch of information on these TVs.
@ajroach42 i believe that is correct
not knowledgeable enough about electronics to know why consumption might different from, uh, tension? but the numbers you supplied do seem correct
@ajroach42 You can't power transformer from 60 to 50 Hz, unfortunately. That will require either a motor-generator or an inverter.
Depending on what it is ... it might Just Work on 60 Hz. Going the other way is more problematic (there's not enough iron in transformers), but 60 Hz is more efficient than 50 Hz, so you're unlikely to smoke transformers/etc. However, AC motors will run at the wrong speed, the waveform can't be used for timing, etc.
@elb Right. A transformer will let me lower the voltage but not increase it.
I'll need an inverter.
It's a TV from 1959 (see http://ajroach42.com/high-definition-television-in-1949/ ) which would have used the frequency of the power to build it's refresh rate. It's part of the timing circuit.
Lemme try that again.
Transformer will raise/lower the voltage, not change the frequency, yeah?
@ajroach42 You can raise or lower voltage, that's not the problem; transformers don't change _frequency_.
@ajroach42 so, going from 60 Hz to 50 Hz is relatively difficult, because it can't be done by a transformer
but yeah, same voltage
what is this device? it's possible that it'll work fine at 60 Hz
I'll need an inverter.
It's a TV from 1959 (see http://ajroach42.com/high-definition-television-in-1949/ ) which would have used the frequency of the power to build it's refresh rate.
@ajroach42 a) those are FREAKING GORGEOUS, and b) it _may_ use the line frequency for timing frames. I don't see where it's doing that on the schematic, though, so maybe not... You ought to ask @crtdude on Twitter if he knows.
@ajroach42 There's a higher quality schematic here, by the way: https://antique-tv-blazianu.pagesperso-orange.fr/TVfrance_TeleaviaP111-439T.pdf
(Linked from the page of photos.)
CRT dude says it won't break anything, and it might even work on 60 hz so I guess I'll try it.
@ajroach42 so if it actually needs 50 Hz, you end up needing a frequency converter, not a transformer (transformer just does voltage)
two ways to do that
the first is mechanical - two 120 volt synchronous motors, one 60 Hz, one 50 Hz, both wound to spin the same speed, coupled together. apply grid power to the first motor, power the TV from the second motor.
the second is electronic - basically you rectify the 60 Hz power to DC, and invert it back to 50 Hz AC. if you do this, you really really REALLY want a pure sine wave inverter.
the other possibility, of course, is that they just didn’t account for 60 Hz when writing the specs
@bhtooefr It's a TV from the 50s, so I imagine it uses the power line frequency for timing. There's a schematic at the link in the second post.
That kind of motor ... generator ?sounds like it'd be Janky and loud, but also like it'd be the quickest route to getting power for this thing.
Thanks for clarification.
@ajroach42 I was under the impression that TVs never actually used the AC line frequency as a time base, instead using RC circuits and the like? and I see a couple for vertical (fréquence image) and horizontal (fréquence ligne) on this schematic
(my understanding was that television field rates followed local grid frequencies so that the cameras could be synchronized to the studio lighting to avoid strobing in the transmitted picture, not so that televisions could use the grid frequency as a time base - if local grid frequency deviates at all from transmitter grid frequency, you’ll get a distorted/rolling picture if you’re using local grid frequency as the time base)
…and it looks like a lot of the power in this TV is immediately rectified (but not all of it) - also not sure how well it works down to 110 volts skimming the schematic in the power section, but admittedly this stuff isn’t my forte
@bhtooefr That makes way more sense.
And yeah, it looks like there's probably a switch or a jumper, but I'll figure that out when it gets here.
it’s a bit of a pita because yeah, its 420ish lines at 50hz, but you can double up under certain conditions and get 840lines out of it.
weird equipment. you could do something like this https://www.mcmaster.com/step-up-transformers/ but the problem is you’re already running 240, depending . :)
@ajroach42 If you see the thing at the lower left of the first page of the schematics that says "BC", I _think_ that's 100V vs 200V power range selector, and it looks like it plugs in in one of two positions and wires the two primary coils in different configurations depending on the mains voltage. Then I suspect the fuse can be easily jumpered to 0, +10, or +20 (the top three taps on the upper half of the primary) to make up "in between" voltages. 1/2
@ajroach42 Since we're now at more like 125 V, you may want to use the +20 tap instead of the +10 tap.
You can check all of this with the variac, of course! 2/2
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