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Water Softener Flow Meter Circuit

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New Member
Hello! I've searched your forums a bit, but have such little electronic experience that I didn't really know what terms to search for. My electronic experience tops out at building a CMOY amp from VERY simple diagrams!

I have a water softner in my house and in calculating salt usage, capacity, etc. the only real variable left is water usage between regenerations e.g. how many gallons are used before it needs to regenerate the media. I'd like to know how many gallons of water I'm actually using between regenerations so I can determine if my filter media needs to be replaced or if it's actually delivering it's rated capacity.

It has a digital controler on top (Amtrol 460i) that has a simple digital readout to set hardness, capacity and current time in addition to a "flow meter" which is just a blinking LED on the display. It blinks when there's water flowing. It has a turbine wheel inside with a little magnet in it which is how it measures the total gallons used, but it doesn't give a readout of the gallons used. I noticed that the light blinks faster when the water is flowing fast and it slows way down when I turn the faucet to a slow flow.

So, I'm wondering if theres a way/easy way to "tap in" to the controller to somehow "count" the number of light blinks and multiply them by a given amount of water used/blink and display that on a readout in total gallons used?

I know I can install an inline flow meter but A) that would involve more plumbing and B) it would cause a slight reduction in flow and C) there's already a flow meter in the softnerthat I'd like to utilize!

Thanks for your advice in advance and I appreciate you keeping it simple! :eek:


You need to determine the number of pulses the turbine flowmeter produces per gallon of water which passes through it.

If you didn't want to actually get inside the controller and attach wires to the circuitry (not sure I'd recommend that anyway), you could devise a counter circuit which has: A) an optical input which gets aimed at the blinking led or B) a hall effect device which would be placed near the moving magnet to detect wheel rotation. Then, it's a matter of accumulating the pulses and performing the calculations required to display the total number of gallons measured.



New Member
Hey Jeff! Thanks for the reply. . .

Yep. .. I know I'm going to have to get a "gallon per pulse" calculation. . . I can even do that math by hand. .I just hope it's consistent.

If I just had a circuit that could count the pulses, then maybe have a "reset" button then that'd be sufficient.

I don't have too much of a problem soldering a couple of leads onto the contact points of the LED. . .after all, I did build the extremely complicated CMOY AMP! :D

However, I like your idea about that "Hall Effect Device" . . The control unit already has one with a wire coming out of it ~ can I just tap into that wire somehow? The "probe" is right next to the Turbine Wheel and has an easily accessible wire coming out and going to my control unit. Might be safer than tapping into the LED?

So. . .is there a simple circuit that can count "pulses" that either come from the LED or my existing "Turbine Wheel Sensor Probe" wire and then just multiply that by my "Pulse Constant"?

Thanks again! :)


New Member
Existing Hall Effect Circuit - Need Digital Output

Okay. . Jeff had a good idea about using a "hall effect" circuit. In fact, the water softener already has one! Theres a probe just outside the Turbine Wheel and the wire is external and goes to the Control Unit Circuit Board.

So, there's obviously an existing circuit on the board that "counts" the revolutions of the turbine and makes the LED blink when water is flowing. IT knows how much water is being used, because that's how it determines when to regenerate ~ after a certain amount of water has passed through.

Now, how do I get that information out of there? Digital readout?

I measured the voltage across the leads coming from the "Hall Effect Probe". There are 3 ~ Red, Black and Green. There's a constant 10.5 volts between the Red and Green. When water is flowing, theres between 5.6 volts and 6.1 volts between the Red and Black. When water isn't flowing, I get 5.6 volts between Red and Black.

So can I either tap into the existing circuit and then feed the output to a digital readout that'll at least give me "total pulses" or, ideally, total gallons used or is there a way to make another circuit that feeds off of the 3 lines coming from the probe?

Thanks again in advance for your help! ;)

PS I have some good close-up pictures of the existing board, probe, etc. if it'll help!


You could tap into the circuit and use the pulses coming from the existing hall-effect sensor. My questions on that would be: A) How do you know which wires to tap into and B) How will the connections you make affect the signal sent to the existing controller circuitry? That is why I would probably recommend an additional hall-effect sensor (if it's possible) which is not electrically connected to the original circuit.


New Member
Hall Effect Sensor Circuit

Hey Jeff! Thanks for getting back to me on this! I have access to the 3 wires coming from the sensor. . .the wires come out of the sensor and attach to the circuit board with a removable connector, so tapping into the sensor wires is easy.

However, you're right. . .I don't how how tapping into the wires will affect the existing signal going to the existing controller circuitry.

The existing sensor fits into a "slot" that's just outside the turbine wheel and picks up the magnetic field. Just for fun, I turned on my water so the LED was flashing which tells me that the sensor is picking up the turbine wheel rotation. Then, I removed the sensor and moved it around the outside of the casing that the turbine wheel is in, to see if I could place an additional sensor somewhere else without tapping into the existing one. . . no luck. Apparently the casing is too thick to pick up the magnetic field. . .don't know exactly what the tolerance is on how far away the sensor can be from the magnet. . .probably 1/distance squared as far as magnetic field loss?

Anyway, you'd have a better idea than me what effect tapping in would have, but I figure it's worth a try, right? IF I tapped in, then what type of circuit would I need to transform the signal/pulses coming from the sensor to a 4 digit 7 segment display? Or, is there any way to tap into my existing board if I took a really nice macro picture of the circuit board?

Thanks again and look forward to your thoughts! :)
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