inductance of a small C-frame motor?

Hello,

What is the approximate inductance of a small 110V C-frame motor, in its native laminated core environment?

I've got a few C-frame motors in my pile of junk, and am wondering if I can just use them as-is in some MC34063 experiments.

Thanks,

Michael

 

[whit3rd]

On Tuesday, March 17, 2015 at 8:18:44 AM UTC-7, mrda...@gmail.com wrote:

Hello,

What is the approximate inductance of a small 110V C-frame motor, in its native laminated core environment?

I've got a few C-frame motors in my pile of junk, and am wondering if I can just use them as-is in some MC34063 experiments.

Basically, the inductance is undefined. If you allow the rotor to move, it turns into
a motor/generator/flywheel, and if you use higher frequency than 60 Hz, you don't
get the core to fully engage (there's a skin depth). So, it is a resistor instead of an
inductor at full power and rated frequency (60 Hz), and a lossy inductor (possibly
1 Henry or so) at low frequency if you clamp the rotor stationary, or use such low
current that friction keeps it stationary. And it's a smaller inductor at higher
frequencies with the rotor clamped.

The variable results you'd get with inductance-measurement devices will just
be confusing: it isn't really intended to be a proper linear circuit element for
the purpose of a switchmode power supply (MC34063). Scavenging a ferrite
bar with a winding from a dead wall-wart power brick is my recommendation.

 

On Wednesday, March 18, 2015 at 1:42:05 PM UTC-7, whit3rd wrote:

On Tuesday, March 17, 2015 at 8:18:44 AM UTC-7, mrda...@gmail.com wrote:
Hello,

What is the approximate inductance of a small 110V C-frame motor, in its native laminated core environment?

I've got a few C-frame motors in my pile of junk, and am wondering if I can just use them as-is in some MC34063 experiments.

Basically, the inductance is undefined. If you allow the rotor to move, it turns into
a motor/generator/flywheel, and if you use higher frequency than 60 Hz, you don't
get the core to fully engage (there's a skin depth). So, it is a resistor instead of an
inductor at full power and rated frequency (60 Hz), and a lossy inductor (possibly
1 Henry or so) at low frequency if you clamp the rotor stationary, or use such low
current that friction keeps it stationary. And it's a smaller inductor at higher
frequencies with the rotor clamped.

The variable results you'd get with inductance-measurement devices will just
be confusing: it isn't really intended to be a proper linear circuit element for
the purpose of a switchmode power supply (MC34063). Scavenging a ferrite
bar with a winding from a dead wall-wart power brick is my recommendation.

Ok thanks!