Paper shredder auto stop?


I have a fairly substantial cross-cut paper shredder that also does CD/DVDs and credit cards that has worked fine for years. Then the optical (break beam) paper present detector failed. To get the shredder working again I simply removed / bypassed the PCB and now simply use the On / Off / Rev switch to manage the unit.

In an effort to make it semi automatic again I plugged it into a Gosund UP111 WiFi (ESP) smart socket and enabled that with a Sonoff Zigbee push-button (Toggle On/Off). Again, so far so good.

However, now I have it automatable, I created an automation that monitors the running power and it works, except that seems to vary quite a bit when idle (unit warm / cold etc) and because the on-load (shredding) power consumption isn’t hugely greater than idle, especially when shredding something light, it’s difficult to pin that down.

alias: Shredder numeric off
description: ""
  - platform: numeric_state
      - sensor.gosundplug06_power
      hours: 0
      minutes: 0
      seconds: 10
    below: 72
condition: []
  - type: turn_off
    device_id: 5334377468b7c0503d60a03d5752fd9a
    entity_id: 33328b8c13881b749498fad94242bfb5
    domain: switch
mode: single

So what I think I might need is something that stops the shredder after say 30 seconds idle, no energy spikes (shredding) but it might need something more subtle to determine when that is?

I was thinking it could be something that could be partly done in the ESP based socket where the instantaneous energy drawn could be measured fairly frequently so it can react to the load more accurately?

Could anyone point me towards something that does similar that I might be able to use please as I’m no coder. ;-(

Why not install your own break beam sensor?
e.g. IR Break Beam Sensor with Premium Wire Header Ends - 5mm LEDs : ID 2168 : Adafruit Industries, Unique & fun DIY electronics and kits

Hi Tom and thanks for the prompt reply and suggestion.

Whilst I could install my own optical sensor, one of the problems with the original setup was that you were obliged to put the paper where the sensor was and that was in the middle. Fine if it was a sheet of A4, not always quite so good if it was a receipt etc.

Ok, I appreciate I could possibly use multiple sensors and even add them to the outside to save having to faff about inside the unit with it’s heavy gears and space issues, I was hoping I could achieve the same goals ‘externally’.

I have done this with my dehumidifier where it sends me a ‘Tank full’ notification when in that state and when the power measured at the smart switch is between two particular values but they seem to be fairly constant so predictable.

I could design and 3D print a slim hopper that sits in the mouth of the shredder with say 2 or 3 sets of optical break beam and using an ESP32 but that that means I have to start designing / building stuff. :wink:

That break beam sensor works up to a max distance of 50cm. You could cover the whole slot.

Assuming it wouldn’t work running the length of the slot (seeing the paper edgewise might not be sufficient to fully interrupt the beam) I’m not sure how I could configure the RX to make it cover the whole length of the slot, no matter how far away the TX could be?

I did build some reflective and encoded IR modules (so they don’t interfere with each other) that I could put along one side of the slot that could work, given the body of the shredder is black and most paper is white? That might also not fail the ‘Don’t want it triggering if I put something on the top of the shredder’ test.

I might be able to design and print a venturi that simply sits over the existing slot and that carries said sensors and an ESP32 etc. I’ll did them out and have a play. :wink: