Counting Water Meter Pulses

[wilafau]

Hi,

I acquired a surplus Badger Meter Model 40 water meter to keep an eye on my homes well water usage. I was pleasantly surprised to discover It has a "generator-type" remote capability so I would like to hook it up via a 1-wire network using Hobby-boards dual counter board. From what I have been able to learn searching the web it looks like this style meter produces short pulses that are are about 8V. This normally drives a solenoid in a remote "Read-o-matic" display unit to advance the dials. The DS2423 spec says that max counter input is Vbat+0.3V. On the Hobby-Boards dual-counter board Vbat is 5V. Id like to know if I can drive the hobby-boards counter input directly by connecting the meter's "-" line to gnd and "+" to counter A or should I do some sort of resistor voltage divider on the meters "+" to keep the pulse under 5v?​

Regards,
Bill

 

[ericvic]

Bill,

You would need some sort of voltage reduction (like a resistor divider) to get the voltage under 5v, I would get it well under 5v since the 1-Wire net can have it's voltage dip to around 4v sometimes.

Eric

 

[sda]

If you lose the +5 (power failure), the counter will be powered by the battery. The battery is only 3v nominal.

 

[wilafau]

If you lose the +5 (power failure), the counter will be powered by the battery. The battery is only 3v nominal.

Thanks sda - good point. At this point it may be safer to use an opto-isolator. I really don't know what the waveform of this "generator" is although since it is a spinning magnet driving something in the meter head that electro-mechanically produces these 8V pulses they will probably be kinda messy. I am going to have to find a scope somewhere and take a look at what the pulses look like to see if I need to put a LPF on it to clean it up a bit before heading into the Opto. (anyone have experience with the MSO-19 USB Osc/LA?)

I'm not an EE so if I am going astray let me know! With these DS2423's being discontinued I cant afford to be blowing these things and I'd like to keep this meter reader on the 1-wire.

 

[ericvic]

I would look at the pulses on the scope and the opto-isolation is a good way to connect it.

The DS2423s are going away but we purchased a large supply on an end of life buy so we should have them available for a good while.

Eric