Re: Good humidity meter?
Richard wrote: Most of the cheap hygrometers are adjustable but are very slow in response and not very accurate at the ends of the range. You can adjust them using the psychrometer and at least get some idea of the trend of RH.I have six of a now-discontinued Radio Shack "LCD Indoor Thermo-Hygrometer," Catalog No. 63-855. I have always been very pleased with these, and they still read within 1 degree and 2% humidity of each other. (The oldest one must be approaching 20 years old by now.) I check them every now and then against some very expensive lab instruments, and they always seem to read within +/- 3% of the humidity indicated by the lab instruments from 20-95% RH and from 5 to 95 degrees C. Plenty good enough for my needs! I have never adjusted any of them. Some more recent Radio Shack units I have (also no longer supplied by RS, as far as I can tell from their on-line catalog) are inferior in a number of ways, and one failed on me outright, but their basic accuracy seems substantially the same (I have several, and they also seem to read within 1 or 2 degrees and 2% RH of the six older ones). RS does still list even newer units. The current RS Cat. No. 63-1032 appears most similar to the older ones I like, with the added feature of a second, remote temperature sensor: http://www.radioshack.com/product/index.jsp?productId=2049773 NB: This type of unit can take as much as 15-20 minutes to stabilize when you move it from one environment to another, or even longer if the temperature or RH change is large. I assume that is true of most of the low-priced electronic sensors. Best regards, etienne |