Accelerometer or what?

Blackbird455

I want to use a BS1 or BS2 to sense , and act, when a 12v pump changes load. I am thinking that using an accelerometer would be the simplest route. For example, one button starts the pump,·PAUSE for 10 seconds, then ,·IF accel value is [noparse][[/noparse]within vibe range of a loaded, "pumping" pump]
THEN, pump for 20 seconds......... IF accel value is [noparse][[/noparse]outside vibe range] THEN [noparse][[/noparse]signal pump to shut down]. IF not continue pumping until accel value is OUTSIDEfor more than 10 seconds.


What do you all think? Is there a simpler , or more reliable way?

Tell me what you would do.

BS1 or BS2?

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Noli nothis permittere te terere

Bruce Bates

Blackbird -

Unless I'm missing something here, it sounds like you want to use a tachometer rather than an accelerometer. A tachometer will indicate motor or shaft speed. Increased load will generally slow a motor, even if only temporarily.

Regards,

Bruce Bates

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Gadgetman

You could also measure the current the motor draws as a motor under light or no load draws less current than one under heavy load.

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Don't visit my new website...

littlerich

Looking at current is a good option especially if you can compare it to shaft rotations.

The reason is for pumps high shaft rotation and low current most likely equals pump cavitating.

Conversely if you have high current and low or no shaft rotations you are looking at a possible jam or stall.

Both conditions you want to detect before you burn out the motor, shear the drive shaft etc

Hope this is of some help and not making matters worse.
Rich

Oh yes and remember to ignore high current while starting a pump as the motor could well draw several times the motor nameplate current while it starts however only for a very short time.

Blackbird455

Bruce,

I think you did miss something.....I want to control the motor based on its condition, not measure the shaft speed of a basically sealed motor.

How would you measure current with a stamp?

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Noli nothis permittere te terere

LilDi

Measuring the current the motor draws is a good way to sense motor load, yes!
The URL below is the specs on a specialized op amp specifically for that purpose.
The LTC6102 in conjunction with an LTC2433 will interface·to a Basic Stamp quite well.
Both of these chips are around a dollar and a half to two dollars each. Very affordable.

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1154,C1009,C1077,P38178

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