Hi,
I want to count pulses from a water meter that provides pulse output via reed switch.
For better noise immunity I want to increase the current thru the reed switch to about 10mA. Will there be considerable degradation of reed switch contacts due to higher current?
Thanks and Regards,
WI
Probably not but if you want to be sure you will have to look up the manufacturer's specifications of your specific reed switch.
Google will show you the spec , the ones I’ve seen will switch a lot more than 10mA.
I’m interested as to why you are having noise problems ? I don’t think reeds bounce , but I would include debouncing in your circuit , if you feeding into an Arduino with long cables I’d look at opto isolation.
Not sure what you have for a switch but my reed switches can support ~1amp.
Reed switches are notorious for bouncing.
Mercury wetted reed switches don’t usually bounce.
If you're using a magnet as a trigger, you might consider a hall-effect sensor to reduce noise instead.
Reed switches are large, fragile, wear over time, and are apparently noisy. Depending on how fast your flowmeter spins, your reed switches may be prone to error or need frequent replacing from constant mechanical deformation.
Hall effect sensors are solid-state, super-compact, and provide an unambiguous clean signal. I've used the TCS40DLR and TCS40DPR,LF quite a bit and love them.
silly_cone:
Reed switches are large, fragile, wear over time, and are apparently noisy. Depending on how fast your flowmeter spins, your reed switches may be prone to error or need frequent replacing from constant mechanical deformation.
Out of curiousity I looked it up. Indeed, they wear - typical numbers I find in the order of 107 to 109 cycles, the lower the current the greater this number. Keeping the current <1 mA will give you the maximum lifespan.