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Can anyone explain why the contact DC voltage rating of relays is often much lower (5x is no exception) than the AC rating?
I think it is due to arcing. With AC an arc will extinguish itself itself when the voltage goes through 0, but for DC no such thing occurs and an long arc can damage the relay contacts.
Could this kind of computer work at 450°C?
Resistors and capacitors for RC circuits should be similar, carbon is good and capacitors are insulator/conductor layers.
I suspect making a temperature controlled oscillator will be very hard. This means power supply AC current might be hard to make.
Anyway rebuilding OP's computer that can run in your kitchen oven would be a nice hobby goal.
https://www.mcmaster.com/high-temperature-insulation/fibergl...
Could this kind of computer work at 450°C?
That's a great question if you're asking about using it on Venus. Copper melts at 1084 C, so you're good there for springs, conductors and contacts. You'd need insulation for wires and circuit boards: something like fiberglass weave would be good up to 537C. No solder, wire wrap, steel posts. Resistors and capacitors for RC circuits should be similar, carbon is good and capacitors are insulator/conductor layers. I su…
Would you really be able to make a spring out of copper? It is my understanding that copper work hardens very quickly, which is a big no-no if you're making a spring, I guess
Could this kind of computer work at 450°C?
That's a great question if you're asking about using it on Venus. Copper melts at 1084 C, so you're good there for springs, conductors and contacts. You'd need insulation for wires and circuit boards: something like fiberglass weave would be good up to 537C. No solder, wire wrap, steel posts. Resistors and capacitors for RC circuits should be similar, carbon is good and capacitors are insulator/conductor layers. I su…
Earlier quoted context omitted.
That's a great question if you're asking about using it on Venus. Copper melts at 1084 C, so you're good there for springs, conductors and contacts. You'd need insulation for wires and circuit boards: something like fiberglass weave would be good up to 537C. No solder, wire wrap, steel posts. Resistors and capacitors for RC circuits should be similar, carbon is good and capacitors are insulator/conductor layers. I su…
> Copper melts at 1084 C, so you're good there for springs Would you really be able to make a spring out of copper? It is my understanding that copper work hardens very quickly, which is a big no-no if you're making a spring, I guess
Earlier quoted context omitted.
I think it is due to arcing. With AC an arc will extinguish itself itself when the voltage goes through 0, but for DC no such thing occurs and an long arc can damage the relay contacts.
Yes I figured that, but the 50/60Hz frequency seems quite low for that to be the case.
Of course a higher frequency would heat the contacts even less, and I imagine you could get a relay rated for even higher voltages given a higher AC frequency.
Earlier quoted context omitted.
Yes I figured that, but the 50/60Hz frequency seems quite low for that to be the case.
50Hz basically means the arc is extinguished after at most 20 milliseconds, limiting how much the contacts heat up. For DC on the other hand there's no guarantee the arc will extinguish at all. You can imagine how a sustained arc would be bad for a relay. Of course a higher frequency would heat the contacts even less, and I imagine you could get a relay rated for even higher voltages given a higher AC frequency.
I suspect the arc could cause the contact to stick for a while, which may increase the arc time.
Could this kind of computer work at 450°C?
The issue with all such computers is developing significant storage. Enough RAM for scientific data and images is probably too energy intensive (electrical energy is hard to get if you have to dump heat at 450C for your RTG). So you either transmit constantly as described here: https://ntrs.nasa.gov/citations/20150002090
or you store it using maybe a magnetic tape with high curie temperature.
Earlier quoted context omitted.
50Hz basically means the arc is extinguished after at most 20 milliseconds, limiting how much the contacts heat up. For DC on the other hand there's no guarantee the arc will extinguish at all. You can imagine how a sustained arc would be bad for a relay. Of course a higher frequency would heat the contacts even less, and I imagine you could get a relay rated for even higher voltages given a higher AC frequency.
But arcs only happen when the contacts are almost-but-not-entirely closed, I suppose (ionization could be a factor). This time-period is, I suppose, very short, much shorter than the 10 milliseconds of the AC half-wave. I suspect the arc could cause the contact to stick for a while, which may increase the arc time.