See now there is another one that was also thought about. But im asking enough , i saw a flow meter from someone on the internet i may take a look at but it will need to output to a warning light.

<b>Mikebits If you monitor motor current you would get instant feedback of a motor failure on a gauge, like no current, max current etc. I suppose while your speeding down the track, you may not look at a gauge. </b>

Thats the issue with the gauge but its true that hte current monitoring is prolly the simlest since even if the impeller came off the motor the load/current would drop since it was just free spinning in liquid but also hard to look at another gauge.

Also the new dash i just ordered this morning


Thanks Mike

 

hi mike,

I have circuit, which detects the extra current that flows in the 12v line, when the motor is not rotating.

Its logic is like, 0.05 ohms resistor is kept in series with the 12v line and during the normal running conditions the drop accross the resistor would be 0.326v.

Whenever the motor is still, the current would increase, thereby increasing the voltage drop accross the resistor. The increase in drop can be identified by a comparator. The comparator output drives the LED.

Whenever the motor is still the LED glows. I have attached the circuit schematic.


Note: The circuit is not tested. This is just a rough design.

Attached Images

Circuit.jpg (29.7 KB, 9 views)

 

Thanks Beenuseren, Ill try building that this week and let ya know how it works out once the pump arrives should be just as easy as removing the motor and stopping the impeller with my hand i would guess * or just using another motor

Regards Mike

 

Two pressure sensors; at inlet and outlet being read by a differential amplifier will tell if it is pumping.
A single differential pressure switch can also be used to turn on a lamp/buzzer.

Miguel

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Abolish the deciBel !

 

Now in a engine application would that work where there is a residual say 16 psi in the cooling system ? I suppose you are just comparing the pressure to see if there is more pressure on the pressure side then the intake side i suppose


Regards Mike

 

Differential pressure sensors and a narrow outlet will not work for liquids as they are incompressible- only for gasses. That's one of the things I learned at work. They also told me if I could figure out a way to measure both high and low liquid flow rates accurately in a small in-line device I'd be rich.

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NO, that picture isn't me so don't bother asking if we can be friends.

 

I have a circuit here;
http://www.romanblack.com/current.htm
that uses one transistor to measure motor over-current and light a LED.
It will also drive a 0-5v signal line you can use to send to a PIC etc.

This is a circuit I have used for years for the same need you have, ie to sense motor jamming or bearing failure.