Is There a Type of Sensor You Need But Have Been Unable to Find?

I've had trouble finding affordable chlorine sensors.

I haven't really checked recently, but most were in the $300 range and up when I last looked. I guess they are quite industrial.

I was looking to automate adding chlorine to a hot tub, using a peristaltic pump to dose liquid chlorine as needed.

I currently use an old-school setup - a floating chlorine puck dispenser

Cheers,

-Nico

How about this reference: https://sensorex.com/pool-chemistry/  . If pH is important, try https://sensorex.com/product/ph5000-swimming-pool-ph-sensor/ . Is this what you were looking at ntewinkel ?

Clem

Thanks Clem!

The only Free Chlorine sensor I found on that site was still a whopping $1040 though - did you see one that's more in line with our usual assortment of Arduino DIY sensors?

pH doesn't change very much, so I haven't bothered with automating it, but those sensors seem to be cheap and plentiful (I see ~$10 ones for aquarium control, for example).

Also, I'm not sure if I could adjust it with a liquid - I use baking soda for alkalinity (which also brings pH up), and pH+ and pH- granules (usually only the +). I suppose they could be pre-dissolved and then dispensed with a pump.

-Nico

Sometimes its not about the type of sensor but its characteristics. For instance you may need a sensor with certain dynamic range, frequency response, noise level, size, weight, etc. A while ago I was looking for a pressure sensor to sense atmospheric pressure, there are many that do that but don't cover up to just a few hundreds meters below sea level. This is sad because it means that you can't use those sensor in deep mines. I found that higher pressure sensors were targeted at measuring pressurized gases, and were not as sensitive.

I would like to find a decent pollen sensor under $100.

Even better if it can determine what type of pollen it is.

I would like to find a throat microphone that is good enough to be used for voice recognition.

At my job, we are looking for an extensive list of exotic sensors. I'm not comfortable identifying them all here, but I can mention  one whole class of sensor we are interested in is non-invasive physiological sensors (many different physiological sensors that are not available today). This is just the tip of the iceberg, I am aware of enormous opportunities to develop new sensor technologies and new sensors. I suspect every industry could use a wide range of new sensor technologies and better sensors. In a few years we will all be amazed at the new sensors that appear in the market.

I bet there is a tamper proof sensor, but I cannot locate one. The use would be to prevent hardware associated with crypto keys from being physically touched.

Clem