I have a power supply that plugs into a 110 volt household outlet (a/c) and produces a 24 volt (dc) supply. I plan to use the 24vdc supply to power the heater bed on a 3D printer. The heater bed has about 6 ohms resistance, and is little more than copper traces that heat up when the power is supplied.
I have a nice Fluke multimeter and am a bit confused by its readings. When I put the positive probe on the 24v positive terminal and the negative probe on the negative terminal, it shows 24 volts. Perfect. However, if I leave the positive probe on the power supply and take the negative probe off the power supply completely, the multimeter still shows a small voltage (maybe a .1 volts); and if I touch the negative probe to anything big (like a nearby metal rack) the multimeter shows over .5 volts. Why is that?
What I'm trying to figure out is whether I can safely turn the heater bed "off" completely by switching the negative wire from the dc power supply? If .5 volts is still getting through somehow, I don't want the heater bed to be staying warm all the time even when I try to turn it off...
I have a nice Fluke multimeter and am a bit confused by its readings. When I put the positive probe on the 24v positive terminal and the negative probe on the negative terminal, it shows 24 volts. Perfect. However, if I leave the positive probe on the power supply and take the negative probe off the power supply completely, the multimeter still shows a small voltage (maybe a .1 volts); and if I touch the negative probe to anything big (like a nearby metal rack) the multimeter shows over .5 volts. Why is that?
What I'm trying to figure out is whether I can safely turn the heater bed "off" completely by switching the negative wire from the dc power supply? If .5 volts is still getting through somehow, I don't want the heater bed to be staying warm all the time even when I try to turn it off...