- cross-posted to:
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- cross-posted to:
- [email protected]
cross-posted from: https://lemmy.world/post/27589038
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Ohm no !
That’s revolting.
First of all, why are they in the chip aisle looking for resistors? Everybody knows they’re in the bread aisle…
I used to make shunt resistors out of a pencil and a piece of paper. Rub pencil all over paper, cut strips to size of required resistance.
EDIT: I mean megaohm resistors not shunt resistors. 20MOhm for DIY theramin.
That’s cool, could you share some photos? The theramin I mean
I admire it but also…wtf lol
There is if you have a potentiometer and a steady enough hand!
U probably need a climate controlled box as well.
Can you even measure that accurately? Like is it physically possible?
I thought it had to do with physicists working off theoretical calculations finding precise values for the circuit and not realizing that components come in discrete values.
Yeah, but they could just calculate the right mix of parallel and series discrete resistors to get there.
It’s gonna make a long BOM though.
Lol, I was actually going to add that but decided it would be too pedantic if I said it myself.
A 11.8 and a 13 in parallel is 6.1854838709677 which is 0.01% off from that resistance. Of course even using matched 1% would screw you as soon as someone opens the door.
I’m too dumb for this joke
I think it’s a joke about physicists not understanding tolerances.
I remember hearing an old story about a company buying signs from a contractor. The contractor produced all kinds of things, so it was fairly straightforward to send them the CAD file and stop worrying about it. One manager did an audit, and realized they were paying hundreds of dollars each for these basic signs. They weren’t fancy or anything, and were just signs throughout the facility that got updated regularly. So why the hell were they paying so much for what should have been a simple print job?
After some investigating, the manager discovered it was because the company didn’t want to hire an artist to design the signs; They just had one of their engineers do it. And the engineer who did the design forgot to change their default tolerances from 3/1000 of an inch. So to comply with the order as written, the contractor was busting out calipers and meticulously measuring the spacing and sizing on each letter before it shipped out the door.
Damn, engineer time isn’t cheap either. Contractor was doing pretty well though
deleted by creator
Fixed resistors
https://en.m.wikipedia.org/wiki/Resistor
The TCR of foil resistors is extremely low, and has been further improved over the years. One range of ultra-precision foil resistors offers a TCR of 0.14 ppm/°C, tolerance ±0.005%, long-term stability (1 year) 25 ppm, (3 years) 50 ppm (further improved 5-fold by hermetic sealing), stability under load (2000 hours) 0.03%, thermal EMF 0.1 μV/°C, noise −42 dB, voltage coefficient 0.1 ppm/V, inductance 0.08 μH, capacitance 0.5 pF.Quantum based resistors :
https://en.m.wikipedia.org/wiki/Quantum_Hall_effect
Quantum Hall effect →
Applications →
Electrical resistance standards :(…) Later, the 2019 revision of the SI fixed exact values of h and e, resulting in an exact
RK = h/e2 = 25812.80745… Ω.(this is precise to at least 10 significant digits)
Quantum Ampere Standard
https://www.nist.gov/noac/technology/current-and-voltage/quantum-ampere-standard
.
https://www.nist.gov/noac/technology/current-and-voltage(…) Quantum-based measurements for voltage and current are moving toward greater miniaturization (…)
(there also been research for defining a quantum based volt standard)
just now realizing that I missed this comm actually
