Silent ALARM KNOB as touch sensor with Telegram support

Silent ALARM KNOB as touch sensor with Telegram message support.

Functions:

• Touch sensitive knob with battery powered ESP32 microcontroller as small alarm system   to silently secure some parts/cabinets/drawers of your home.
• Even if you don’t use the alarm system part, I think the knob could look quiet good if you choose your favourite colours and wire color…
• If the button is touched/used the ESP32 will wake up from a deep sleep standby mode and will silently send a Telegram message via your WiFi to let you know about the knob usage. After that the microcontroller will fall to deep sleep again.
• The here provided knob allows to route the shown silver copper wire in Ø0.6mm diameter on the outside so that touch actions at the knob will be registered.
• With the named 1.100mAh battery the microcontroller should operate for months - depending on how often it is used and the environment conditions like your WiFi signal strength.
• Note: The device should work with any knobs that are electrically conductive.

Parts needed:

• 1x ESP32 Lolin32 
• 1x 0,25mm² wire
• 1x 1100mAh LiPo battery with JST plug
• 1x silver copper wire in Ø0.6mm diameter 
• 1x cable lug M4
• 1x M4 countersunk screw
• 2x M4 washer
• 1x M4 nut
• 2x M2x10 screw to fix the ESP32 inside its case 
• 2x 4mm wood screw (if you want to screw the case in place)

Code:

• The required code can be found in my GitHub repository.
• Adding the device to your WiFi and changing the settings for f.e. your Telegram config can simply be done by changing the code in the settings file. Please see extra descriptions there…
• A small manual how to setup the required Telegram bot for the device can be found in the settings of the code as well.

Wiring: 

• The silver copper wires ends are hidden inside the knob and the electric signal is transferred by the used screw to the inside of your cabinet or drawer, so no extra wire needed though the hole of the cabinet or drawer. On the inside of the cabinet or drawer an extra wire is attached to the end of the screw with a cable lug to be able to contact the knob to the ESP32 pin 4 in its case. That’s it… 1 wire to attach only…
• Solder the wire to the cable lug, attach it to the screw between the washers.
• Route the wire into the case and solder it to pin 4 of the ESP32. 
• Plugin the LiPo battery with the JST connector to the microcontroller.

Adding the silver copper wire to the knob:

• Mounting the wire to the knob should be easy with the holes and channels added to the knob for 0.6mm wire. 
• Route the beginning of the wire through the holes of the back and inner part of the knob like shown in the pictures.
• It really makes a difference to straighten slightly the wire before using it by pulling it a little bit. I had no vise available for this little project, so my wires are not really straight…
• Add the 12 silver copper wires to the 12 channels/holes as shown and fix them in the base like shown.
• Make sure not to make the wires too tight because the M4 countersunk screw is supposed to clamp them even more when screwing the knob in place with the nut.
• Take care to hide and bend all sharp wire ends inside of the ring of the knobs base to avoid damage on your piece of furniture.

Printing instructions:

• Knob:
  • 0.2 speed profile
  • Supports from the print bed
  • Ironing for the top layer 
  • No brim needed
• ESP32 case:
  • 0.3 draft profile 
  • No supports needed
  • No brim needed

Happy printing :)