Or just use a 1.2V battery... its only off by 20% right :^P<br> <br> Suppose you have a crapy meter....<br> <br> You can't measure resistance with any precision... BUT even a cheap<br> meter will usually repeat a measurement with very good repeatability.<br> <br> So you could match resistors pretty well with a crap meter. You would not<br> know if they were 1K, or 1.2K, or .90K... but you could say with some<br> "confidence" (is it ?) that they were equal in value.<br> <br> Or get just TWO precision resistors, build a Wheatstone bridge, and use your crappy meter to find the null voltage. It may be .2V or .02V... but you can usually<br> have "confidence" that the meter is monotonic at least. You can match<br> resistors to very good precision.<br> <br> Or go to Mouser.com and BUY the 0.1% resistors... they are about $1.00<br> each. I'd buy the bag of 200 1% parts and match them using the crude<br> methods I've described.<br> <b!
r> Now
the voltage reference is the ONE part you cannot easily verify with cheap<br> equipment... but as was pointed out in the "oven controlled reference" post<br> yesterday... a $5 surplus part might give you all you need and a $20 calibration<br> with a known accurate meter would finish the job.<br> <br> I made these little calibration aids for myself so that I can quickly verify<br> VCO operation. If you do that very often, maybe you can afford the very<br> expensive meter.<br> <br> I prefer to spend the money on synths...<br> <br> Samppa wrote:<br> <blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><harrybissell @prodigy.net="">Let's try this other way: Make a precision voltage reference. Then<br>take Your good old bag of 5% tolerance resistors, match a batch (I say<br>stick 'em to styrofloam, let them reach the room temperature ect.)<br>with Your badly or non-calibrated meter and build a resistive
divider<br>from Your precision voltage reference down to GND.<br><br>Then look at the results with the "Pro precision gear" - How badly<br>voltages were off?<br> </harrybissell></blockquote>If you were "MOTM" this would never work. If you were "EFM" it is precisely how you would do it. Suppose that PAiA required this kind of<br> test equipment, would they remain in business ???<br> <br> Sometimes cheap and dirty really HAS merit. Its not the ideal way to go, but<br> with careful planning you can do far better than the accuracy of your equipment seems to allow.<br> <br> H^) harry<br>