Proximity Sensor, Mk I
Project Sheet
created February-March 2021


24 March 2021, Finished
Proximity Sensor, Mk I

This was a fun project.  I learned a lot and ended up with a very useful device.

I’m glad that I chose to utilize two different sensor technologies (PIR and UltraSonic).  These two sensors seem to compliment each other very nicely.

I took an automaton and this proximity sensor to my dentist yesterday…set everything up in the waiting room.  First time in public.  It performed very well.  I left the pair in the waiting room while I was getting my teeth cleaned.  It performed flawlessly.

I realize now that I will indeed be wanting more of these.  Already in my mind is the Mark II model, which will be built right into an automaton.  It will be composed of two components…the sensor head, and the processor/power unit.  The processor/power unit will be on the underside and to the rear of the automaton.

The Proximity Sensor Mk I with its top cover off. 21 March 2021.
Auger Lift #1 and the new Proximity Sensor Mk i. 21 March 2021.

17 March 2021.  Learning to Assemble
Proximity Sensor, Mk I

I’m at the point in this project where I know that I will be successful.  Now I’ve got to determine how to package all of this.  There are a couple of things to consider:

  • I want to be able to “aim” the unit so that it can point at the most probable traffic path.
  • I want it to be heavy enough that the two cords coming out of its rear end won’t drag it around.
  • I want it large enough that it could be ‘hidden’ under a vase of flowers or a book or whatever.

Another thing that I’m considering is that I probably will want one of these for many of the automata that I create…so I want to design such that I can sort of mass produce them.

The components need to be held down. I’m experimenting with 3d printing holders for things.  It’s interesting…I’ve roamed around the web and on YouTube and don’t see lots of consideration to packaging.  Perhaps I’m not calling things by the right name.  

I’ve decided to use 3d printed sides, and a 1/2″ plywood bottom and top.  This should give me the weight that I want.

As you can see I’m having a bit of fun with the location of the sensors and LEDs.  

Experimentation with component hold-downs. Here you see the Mean Well power supply and relay shield hold-downs. 8 March 2021
A holder for the Arduino Nano. 10 March 2021
Experimentation with 3D printed container sides. 13 March 2021.

27 February 2021, Containing
Proximity Sensor, Mk I

I’ve chosen the Arduino platform for Proximity Sensor Mk I.  This is my first “real” Arduino project.  Before starting I outlined my objectives:

  • Turn on an automaton when a human is present, and turn it off after X seconds of non-human detection.  I’m assuming that a large dog would operate this also (which my Golden Retriever has since proven to be true).
  • Additionally, be able to act as a simple on-off switch.  The sensor is bypassed in this mode.
  • The unit is to stand alone, is to be about the size of a cigar box.
  • Will have a standard receptacle on the back so that the automaton can be plugged in.  
  • A 3 amp circuit breaker.
  • Indicator lights.
  • A three-position switch.

For starters I created an Arduino ‘workbench’ for myself, using one of my cafeteria trays.  Onboard is a 110 volt supply with a 3 amp circuit breaker and an on-off switch.

The initial process is called breadboarding.  This is when the components are connected together and the software is developed.  I began this process using an Arduino Starter Kit that I acquired a few years ago.  The IDE that is used is the on-line Arduino Create IDE.

I had initially anticipated using a PIR (Passive InfraRed sensor) only, however, found that the PIR lost track of a stationary human, so I opted to use an UltraSonic sensor in addition to the PIR.  In the second image you see the PIR, Ultrasonic, and LEDs all mounted on a tree.  This tree allowed me to easily move and aim the sensors as I experimented.


The Arduino workbench and most of the Proximity Sensor components. The Arduino Uno is foreground. Immediately behind is the much smaller Arduino Nano. To the right are the PIR and the relay shield, and to the rear is the Mean Well power supply. February 23, 2021
The Proximity Sensor in the breadboard phase of development. March 7, 2021.