- #36
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Just a few quick comments - it's very likely that one will be able to use a voltmeter as an ammeter for this application.
If one has a 2volt full-scale voltmeter witha 10 megaohm input impedance, it can be considered to be a 200na current meter with a 10 megaohm series impedance. Usually 10 megs is too high a series impedance to be useful for a current meter, but this case seems likely to be an exception.
If the brick starts to conduct too well at high temepratures, the series impedance can be reduced by adding a paralllel resistor (which will degrade the senistivity of the current meter, but this won't be a problem if the current is high).
While it would be theoretically possible to convert an old TV set to yield a 20,000 volt DC power supply, I wouldn't recommend it. Aside from the safety issues, it will probably be difficult to measure voltages much over 1000 volts with standard equipment. I'd try to keep voltages under 1000 volts unless there was no other way to do the experiment. You'd only get a factor of 20 in sensitivity from going from 1000 v to 20kv anyway.
I would suggest a transformer and a full-wave bridge rectifier circuit for the high voltage power supply if a 1000 volt variable power supply is considered to be "not standard equipment". Several approaches exist for varying the voltage (variacs are one).
Procuring an actual brick and attempting to measure it's resistance or IV curve at room temperature would probably be a good way to get a handle on what's needed.
A good experimenter would measure several points on the voltage-current curve of the brick, to see how linear it was.
The art department would probably have some sort of kiln - whether or not they'd let you drill holes in it is another issue.
If one has a 2volt full-scale voltmeter witha 10 megaohm input impedance, it can be considered to be a 200na current meter with a 10 megaohm series impedance. Usually 10 megs is too high a series impedance to be useful for a current meter, but this case seems likely to be an exception.
If the brick starts to conduct too well at high temepratures, the series impedance can be reduced by adding a paralllel resistor (which will degrade the senistivity of the current meter, but this won't be a problem if the current is high).
While it would be theoretically possible to convert an old TV set to yield a 20,000 volt DC power supply, I wouldn't recommend it. Aside from the safety issues, it will probably be difficult to measure voltages much over 1000 volts with standard equipment. I'd try to keep voltages under 1000 volts unless there was no other way to do the experiment. You'd only get a factor of 20 in sensitivity from going from 1000 v to 20kv anyway.
I would suggest a transformer and a full-wave bridge rectifier circuit for the high voltage power supply if a 1000 volt variable power supply is considered to be "not standard equipment". Several approaches exist for varying the voltage (variacs are one).
Procuring an actual brick and attempting to measure it's resistance or IV curve at room temperature would probably be a good way to get a handle on what's needed.
A good experimenter would measure several points on the voltage-current curve of the brick, to see how linear it was.
The art department would probably have some sort of kiln - whether or not they'd let you drill holes in it is another issue.
lol, reply.