The Ossie motor

[Jimboot]

Amps somewhere around zero on the 1amp meter. voltage1.322 pu coil voltage 2.20. Now to try to get that back into the battery. rpms580

[Jimboot]

Trying to make use of the voltage on pu coils. It's coming off a schottky bridge rectifier. I measure by putting a cap in parallel. I assuming I need to ditch the cap. Not sure what after that.

[gyulasun]

trying to get an accurate amp reading. I switched to a 1 milliamp meter during the run & it was bouncing at 0.5ma then it gradually stopped & I couldn't start it again without switching it out. These are passive analogue meters as pictured above. I have it running at the moment via a multimeter on 250milliamp setting. The meter is in series like the analogue ones. ONce again it affects the tuning of the motor. It runs at around 100rpm on 10dcma according to the meter. If I use say 20milliamps I get 370rpm but the voltage fluctuates wildly. between 1.300 - 1.312. What are the meters doing to the current that would affect the motor so much?

Hi Jim,

Any meter has got an inner resistance, what is more analog meters have inner inductance due to the coil they have inside by default, and the coil has the wire resistance of course, in digital or analog multimeters this inner resistance comes from the series shunt resistances, depending on the range switch settings.

IF you have a digital meter, you can check your 1mA and your 1A analog meter inner resistances simply by measuring at their connecting points by your digital Ohm meter.  (Make sure the polarity coming from the Ohm meter tips would not bang out the 1mA meter to full deflection, this depends on the range switch on your Ohm meter, start in the kOhm range.)

Your finding with the 1mA meter halting the motor sounds strange, at the moment I can only think the meter has got high enough inner resistance to drop voltage from the battery.  And what you find with the increasing RPM by using the higher range settings on your multimeter surely means a decreasing voltage drop across the meter.
The fluctuation may come from the analog meter coil's self inductance (some L-R time constant's coincidence).

In your latest video where is the pickup coil?  (I can see a small flat coil slanting on the back of the big coil?)

Gyula

[Jimboot]

lit up a couple of leds with the pu charge. pretty dim tho.

[Jimboot]

Hi Jim,

Any meter has got an inner resistance, what is more analog meters have inner inductance due to the coil they have inside by default, and the coil has the wire resistance of course, in digital ammeters this inner resistance comes from the series shunt resistances, depending on the range switch settings.

IF you have a digital meter, you can check your 1mA and your 1A analog meter inner resistances simply by measuring at their connecting points by your digital Ohm meter.  (Make sure the polarity coming from the Ohm meter tips would not bang out the 1mA meter to full deflection, this depends on the range switch on your Ohm meter, start in the kOhm range.)

Your finding with the 1mA meter halting the motor sounds strange, at the moment I can only think the meter has got high enough inner resistance to drop voltage from the battery.  And what you find with the increasing RPM by using the higher range settings on your multimeter surely means a decreasing voltage drop across the meter.
The fluctuation may come from the analog meter coil's self inductance (some L-R time constant's coincidence).

In your latest video where is the pickup coil?  (I can see a small flat coil slanting on the back of the big coil?)

Gyula

Thanks Gyula. The pu aren't hooked up in that vid. I have 3 where I used to have the drive coils. I'll do some measuring. I'm guessing the current from the pu is very low given my test with the leds. Is it still possible to get it back into the motor if it has low amp but higher voltage?