I finally got this taken apart.
The star wheel has magnets embedded in each point.
There is a sensor inserted in the top of the housing to pick up the rotation.
I'm not sure what type of sensor it is, maybe a Hall Effect?
If it is, then it should be possible to wire it for RPM reading?
There are two chips on the board.
One is a Fairchild CD4538BC, Dual Precision Monostable.
The other is a Onsemi MC14013B Dual Type D Flip-Flop.
I have no clue about these.
The relay is a Aromat (now owned by Panasonic) DF2E-DC24V DF Series Dual Coil DPDT 24V 300mA Latching Relay.
Maybe this can be replaced with a 12V relay?
A potentiometer was glued to the top of the relay.
It is used to set the the trigger point for the relay.
From what I understand, if the rotional speed drops below the set point the relay will be triggered.
This seems to suggest that the sensor can determine rotational speeds, not just that it's turning.
What I'd like to do is modify the circuit to give out rpm speeds to be connected to a fan header.
Use the onboard relay to shutdown the system if the rotation stops due to the pump failing and the systems fails to shut itself off.
Maybe set off an warning alarm also.
I need the real tech gurus to help me with the electronics side of things.
I can solder, etch my own boards but I'm not an engineer.
Anybody feel like helping me out?
Here are the data sheets for the chips and relay...
http://home.earthlink.net/~dsptech1/rfs-2500/1462.pdf
http://home.earthlink.net/~dsptech1/...0/CD4538BC.pdf
http://home.earthlink.net/~dsptech1/...0/MC14013B.pdf
Data sheets for the RFS-2500...
http://home.earthlink.net/~dsptech1/rfs-2500/RFS.pdf
http://home.earthlink.net/~dsptech1/...0/RFS-2500.pdf
Some images....
http://home.earthlink.net/~dsptech1/rfs-2500/Board.JPG
http://home.earthlink.net/~dsptech1/rfs-2500/Board1.JPG
http://home.earthlink.net/~dsptech1/rfs-2500/Sensor.JPG
http://home.earthlink.net/~dsptech1/...r-location.JPG