| General > General Technical Chat |
| What happend to 320K resistors ? |
| << < (23/27) > >> |
| drussell:
--- Quote from: Monkeh on February 26, 2021, 05:42:07 pm --- --- Quote from: Jan Audio on February 26, 2021, 03:33:16 pm --- --- Quote from: Monkeh on February 26, 2021, 02:33:41 pm ---You could be long finished by now making your two boards. --- End quote --- What boards ?, i dont make anything with this, i just have some tricks in my trickbox. --- End quote --- So let me get this straight, you're complaining about the expense of buying parts you shouldn't have chosen and don't need? --- End quote --- Yeah... Yup... Pretty much... ;) For some unknown reason, instead of just ignoring this thread from the get-go, I've been watching with :popcorn: |
| drussell:
--- Quote from: JohnnyMalaria on February 26, 2021, 05:48:37 pm --- --- Quote from: drussell on February 26, 2021, 03:22:29 pm ---I'm not sure why you can't picture this in your mind's eye, but okay then... --- End quote --- OT - not everyone has a mind's eye, including me. It's called aphantasia. It wasn't until I was about 50 that I learned that most people really can create images in their heads. Blew my mind. I can't explain it but, taking the example of the two resistors, I can conceive it in my mind and know what it's all about but I don't visualize anything. --- End quote --- I realize that someone might not be able to fully "visualize" a concept, especially one that is outside what they have really ever considered before, which is why I have no problem posting a picture of what I'm talking about. I just didn't expect that the idea of putting two resistors physically in series would be any sort of an abstract concept. There are many physical forms to easily achieve the desired result. (As to the sanity of stressing over the absolutely precise, <1% accuracy of a poorly chosen component value in this specific type of circuit, I am less sure. Why something like a 316 or 324 or somesuch value wouldn't be considered completely adequate and appropriate in a 6-bit DAC circuit, let alone choosing more sane values in the first place, I have no idea. :popcorn:) |
| drussell:
--- Quote from: Jan Audio on February 26, 2021, 02:19:20 pm ---It seems very hard to make a 320K resistor like this. --- End quote --- --- Quote from: AndyC_772 on February 26, 2021, 02:35:45 pm ---470k // 1M = 319.728k, which is an error of -0.085%. Also try 365k // 2.61M = 320.218k, or 332k // 8.87M = 320.022k. --- End quote --- Indeed. I'm not sure why the OP is so obsessed with such tight tolerance of this particular value, but even a paralleled set of commonly available 560K and 750K values gets more than close enough for any reason which I can conceive of. |
| drussell:
--- Quote from: ebastler on February 26, 2021, 08:23:33 pm --- --- Quote from: Jan Audio on February 26, 2021, 02:19:20 pm ---It seems very hard to make a 320K resistor like this. --- End quote --- If you can live with 320.5K then you could use 390K and 1.8M in parallel. Both are E12 values. --- End quote --- As long as you get 1% or better spec'd resistors you could obviously use a bunch of different combinations, and sure, many common values are available in even tighter tolerance versions which you can use for getting unnecessarily close to some particular value if you wish. I still don't think the OP is actually trying to create a .01% accurate 6-bit DAC, even though they seem to think they are. ::) Usually when precise matching is required, binned testing of incoming lower-tolerance yet stable components would be sorted into matched pairs/quads or whatever and then specifically indicated as selected components on the schematics and BOM. It still seems silly that the OP is "needing" something so precise in the first place, given the tolerance of typical components used in such situations, but... :popcorn: |
| Jan Audio:
--- Quote from: Monkeh on February 26, 2021, 05:42:07 pm ---So let me get this straight, you're complaining about the expense of buying parts you shouldn't have chosen and don't need? --- End quote --- Yes. |
| Navigation |
| Message Index |
| Next page |
| Previous page |