Ed Lenzs' microwave generator

[artv]

I was wondering about the turn table motor its just one coil of very thin wire with a circular magnet in the center that has four poles 2 of each ,when I spin it with my cordless drill ,my meter says I'm getting 40-50vac but won't read any current why is this I forget the resistance but is...E=I*R

[ghurd]

Obvious common problems is the meter's fuse is blown, or the ammeter is set to DC.
G-

[artv]

yes I think it's a blown fuse in meter reads 115vac plugged into wall socket but no current what so ever....................thanx for your help

[ghurd]

yes I think it's a blown fuse in meter reads 115vac plugged into wall socket but no current what so ever....................thanx for your help

No current in a 110VAC socket?
That's what blows fuses!

[artv]

lol......no I had the turn table motor plugged in and was checking leads on it for volts ac 115 and current but no current reading

[Bruce S]

Another reason could be that you're trying to read Amps while the meter is in Voltage mode?

Even the cheapo DMMs is have, you have to move the Red to a different plug in and switch to Amps, start out highest possible selection switch to lower readings while working with motor.

Cheers;
Bruce S

[zap]

A little off topic but...

Grab a pair of pliers and give the motor a good turn whilst the two leads are touching you or a loved one

Or... use it out in the yard and get enough worms to fill a coffee can.

[Norm]

Note to self: Do Not try to read voltage of a battery or whatever while
DMM is in Ammeter mode !
Seems like it usually blows the DMMs fuse ( voice of experience.....many times )
LOL

[dsmith1427]

don't you need a know load to measure amps?  I thought you had to add a load to the circuit, such as a light bult, break the circuit and measure the current in line with the load... Does this make sense?

Don

[12AX7]

just to clear up some confusion (maybe on my part)

You can't measure current with out a load.    Current doesn't flow unless there is a "path".  and the path is from the voltage source through the circuit wiring through the "load" and back to the voltage source.   You should be able to measure the current at any point in the circuit by "breaking" the circuit and placing the amp meter in series with the load.
Normally you're amp meter will indirectly tell you what your load resistance/impedance is, using ohms law.

An amp meter should be thought of as a "short circuit"   you should never use a "standard" amp meter to measure the current coming from (there isn't any with out a load) a voltage/power source.
To do so would be the same as "shorting" out the power source,  whether the power coming from an homes AC outlet, a generator/alternator, AC/DC power supply or a battery.
Trying to do so will almost ALWAYS result in something ugly.   If you're lucky, just a fuse will pop,  if your not....   melting wires.. fire...  death and other nasty things.

[Junkie]

I think I've lost count of number of multi-meter fuses I've blown trying to measure voltage with it set to amps 

[artv]

so how does the flux linkage occur in this arrangement...............art v

[ghurd]

Hard to ay without a couple good photos.
Probably something on the order of Ed's Mini-Gen kit,
http://www.windstuffnow.com/main/mini-gen.htm

All the Ns line up with the inner pole piece, while the Ss line up with the outer pole piece.
Then the wind moves the magnet disk, which changes the polarity on the pole pieces, and through the coil.
G-

[joestue]

I was wondering about the turn table motor its just one coil of very thin wire with a circular magnet in the center that has four poles 2 of each ,when I spin it with my cordless drill ,my meter says I'm getting 40-50vac but won't read any current why is this I forget the resistance but is...E=I*R

you taking about those gear motors that are about 3 cubic inches in size? if by spin with a drill what do you mean? if you turn it by hand at 2-4 rpm you should get near 100 vac out of those things.

the motor itself is ac synchronous, pole pieces are made from bend sheet metal. You will need an ac current meter. At 3 watts normal operation, maybe 50% power factor you are looking at a max current of 40ma, and as you are running it backwards all those losses work against you, so at most you could get 40mA at say 60vac out of that thing.

[willib]

don't you need a know load to measure amps?  I thought you had to add a load to the circuit, such as a light bult, break the circuit and measure the current in line with the load... Does this make sense?

Don

Yes thats how its done.. Unless you are absolutely sure that the current you are trying to read is less than the rating on the fuse.
For instance i've hooked my Ammeter directly across my alternator output many times ,But each time i made sure that the current was not high enough to blow the fuse..
the fuse in my meter is rated at 10 Amps.
and then of course there have been other times when i've mistakenly had the meter on Amps and touched 120V at the breaker box , a brief spark , and a little fused metal on the meter leads ,and some time to calm down from the Whoa ! , but thats what the fuse is for, to protect the meter.
However a fuse will not protect you from your own (my own) carelessness.