twong@civil.ubc.ca (Thomas Wong) (12/04/90)
Hello. I'm having problems with my aquarium heater and I was wondering
if anyone might be able to help. During the heater on/off transition stage,
the heater not only makes static noises which I can hear, but it also
creates some high frequency interference that disrupts the reception of
my AM radios. This happens on my stereo that plugs into the wall and
on my portable that uses batteries so it must be in the air and not
in the house circuit (ie. plugging the heater into a noise filter which
then plugs into the outlet would not help. I've tried that too actually,
and I was right, it didn't stop the static) I've had this problem for
a number of years actually, I finally couldn't stand it anymore earlier
this year and I replaced the heater with a new one. Then came summer and
the thing didn't have to go on anymore. Now that it's getting cold
again, the heater is being used and the static on my radio is back.
Argh! Anyone else have this problem? Anyone found a solution for this?
Thanks in advance.
Thomas.
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/*----------------------------------------------------------------------*/whit@milton.u.washington.edu (John Whitmore) (12/04/90)
In article <1990Dec3.222022.6991@unixg.ubc.ca> twong@civil.ubc.ca (Thomas Wong) writes: > >Hello. I'm having problems with my aquarium heater and I was wondering >if anyone might be able to help. During the heater on/off transition stage, >the heater not only makes static noises which I can hear, but it also >creates some high frequency interference that disrupts the reception of >my AM radios. Either switch bounce or the Neon pilot light can cause RF output from an aquarium heater. A simple ceramic capacitor across the AC power line, located as near the switch/pilot light as possible, should cut the noise. Try for 0.01 uF, 500 WVDC; Radio Shack has this as 272-131, for 500 millibucks, or 272-160 for a little higher breakdown voltage. A more elaborate scheme would be to use the mechanical switch to trigger a triac (solid state AC switch) so heater startup would make only a single 'tick' rather than multiple bounces. The last time I looked at aquarium heaters, they seemed to have room for such things. John Whitmore