I am looking for a sensor that can detect a hand for a automatic soap dispenser.

Question

Hello,

I want to build an automatic soap dispenser. I already tried those cheap IR sensors (see below) they work fine but only when there is no sun.

Sunlight triggers it. Are there some other cheap alternatives that have a short-range 5-10cm but also work in daylight?

Thanks!

javagoza · Answer

I used a Vishay VCNL4040 sensor for a design that I made of an automatic faucet with proximity sensor and voice controlled water temperature. The VCNL4040 integrates a proximity sensor (PS), ambient light sensor (ALS), and a high power IRED. https://cdn.sparkfun.com/assets/2/3/8/f/c/VCNL4040_Datasheet.pdf Sparkfun has a module with that sensor https://www.sparkfun.com/products/15177 I have not used it outdoors, but if you tell me the use case I could run a test. I am located in Spain.

dougw · Answer

These low cost PIR PIR sensors work well:

fmilburn · Answer

Hi Mark, I reviewed a sensor that can work in that application here: https://www.element14.com/community/roadTestReviews/3403/l/omron-sensor-evaluation-board-2jcie-ev-review Page down to the section on optical sensors.

Jan Cumps · Answer

There are some things you can do to deal with sunlight: - put a (long) tube on top of the LEDS. So that the only valid path of light is from the sender to the receiver. - send a known pattern via the sender, and only react when that known pattern is broken.

BigG · Answer

How about proximity sensing using capacitance sensing tech.

Here's an example / app note from Infineon-Cypress on Proximity Sensing with CapSense: https://www.cypress.com/documentation/application-notes/an92239-proximity-sensing-capsense

obones · Answer

The soap dispenser that I have here, sold by LIDL, has the receiver part at the top location, facing downward inside a tunnel, while the emitting led is at the bottom facing up. This way, there is very little ambient light coming towards the sensor. You simply have to place your hand in that angled beam and the soap is pumped up. So the first thing that I would try with the "cheap" version is to separate emitter and receiver to create a real barrier, not a reflection based sensor.

I am looking for a sensor that can detect a hand for a automatic soap dispenser.

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