Interesting comments, thank you.
1. The DS18S20 is a sensor I happened to have around unused. Tim is
correct - it doesn't need/use the 5v.
2. It WAS the freezer. I turned it off for two hours and the
oscillation stopped and resumed after switching on again. The air in the
summerhouse is very static - only ventilation is what comes through the
keyhole. The heat given off from the condenser cooling coils must be
what's driving the temperature variation, and I know that RH varies with
temperature, but why such a small variation can affect humidity readings
by 2 % points I can't imagine. Any physicists out there?
I think I'm not going to concern myself further now that I know the cause.
Regards to all
Graeme
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