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Automatic dishwasher opener

Automatically open the dishwasher when it finishes to improve drying

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High-end dishwashers have drying systems by means of TEC condensers or gates for ventilation, but most don't.

Opening the door after the program finishes helps getting all the moisture out and avoids condensation and water marks on the dishes, sometimes even bad smells if you leave it overnight.

An actuator behind the scenes is commanded by a microcontroller that uses a microphone to listen for the "beep" sequence at the end of the program, then opens the door for you.


The actuator is installed in the adjacent cabinet and everything is hidden by the door (open and not seen in the video). The actuator pushes the cabinet door and the dishwasher door at the same time, then hides out of sight.

Acknowledgements: Thanks to by brother for printing the actuator "finger" and brackets in his 3D printer, to my father for helping me improve the LM358 preamp, and to my girlfriend for whistling along at exactly 3.969 kHz during the detector testing.

  • Enclosure and final setup

    Ivan Stepaniuk5 days ago 0 comments

    A cheap enclosure holds all the electronics, left to right: the H-bridge DC motor driver, ESP8266 board, STM32F103 bluepill board, and LM358 amplifier with microphone.

    During the last minute I resoldered the microphone so it aligns perfectly with the whole on the enclosure so I would not have to raise the gain. It is quite sensitive but the software waits for 3 beeps spaced 6 seconds apart. It seems quite reliable.

  • Test with the real dishwasher

    Ivan Stepaniuk11/16/2020 at 22:58 0 comments

    So far I have only tested by generating the tones with Audacity. Here is a short video of the detector reacting to the dishwasher beeps (not the end of cycle long beeps, but it's the same frequency.)

  • Detector working

    Ivan Stepaniuk11/16/2020 at 13:11 0 comments

    A cheap microphone capsule salvaged from the junk bin, together the old and ugly LM358 as preamp, feed the audio signal to the STM32F103 (bluepill, bottom dev kit). For this MCU, at 72 MHz, with a DMA capable 12-bit ADC, sampling the audio is a walk in the park. I plan to use the ESP (top) to do the IoT / wifi part of this project.

    Ideally you'd use just one MCU, but the ESP has a very slow ADC that is not intended for audio, and though I have a couple SPI codecs (the unconnected Microchip part on the upper breadboard), it was much simpler to do the heavy ADC+processing job on the ARM Cortex chip.

    Parts wise... the bluepill is even cheaper than the SPI ADC part!

  • Beep, beep, beep

    Ivan Stepaniuk11/15/2020 at 22:05 0 comments

    After a quick recording with my phone, the Audacity frequency plot reveals that my dishwasher end-of-cycle tones are at 3.969 kHz.


    At first I thought that it was probably 4 kHz and my measurement had some error, but no, it's exactly 3.969 kHz. Probably, the MCU inside the dishwasher is using an imprecise RC clock generator, or perhaps this tone was easier to obtain by dividing the MCU clock. In any case, it's different enough from 4 kHz to take it into account when detecting the tones. Nobody wants the dishwasher opening when the microwave beeps!

  • IT'S ALIVE!

    Ivan Stepaniuk11/08/2020 at 17:39 0 comments

  • Actuator clamps and business end

    Ivan Stepaniuk10/31/2020 at 01:29 0 comments

    I designed two clamps and a  "finger" (that hopefully won't snap!) It's just 3mm thick. If it breaks I will have to redo the end with something stronger

  • Chinesium actuator

    Ivan Stepaniuk06/03/2020 at 19:18 0 comments

    Most of the mechanic part of this hack will be built around a suitable actuator than can push my dishwasher door open. I ordered one of these, with a 200mm travel and rated at 700N it should be more than capable of opening the door. Speed is not really important.

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Discussions

Mike Szczys wrote 3 days ago point

Smooth operation, nice job getting this one across the finish line!

  Are you sure? yes | no

Ivan Stepaniuk wrote 3 days ago point

@BharbourI I discovered that my BOSCH dishwasher has a button combination to enable/disable the beeping. Maybe yours has such combination too.

  Are you sure? yes | no

Bharbour wrote 3 days ago point

Thanks, I will check the manual.

  Are you sure? yes | no

Dan Maloney wrote 06/01/2020 at 20:45 point

I, too, prefer my dishes air-dried - I've seen that high-power heating element warp even heavy stoneware plates.

Seems like you'll need to figure out a way to trip the mechanical lock on the door - any thoughts about how you'll tackle that?

  Are you sure? yes | no

Ivan Stepaniuk wrote 06/02/2020 at 19:34 point

Thanks for your input! By lock I think you mean the type of latch that would be actuated by the door handle; thankfully my dishwasher, a basic BOSCH, only needs you to pull the door with a certain force and it will just snap open. I think this is the case for most built-in/integrated dishwashers. I ended up ordering a slow and cheap linear actuator, china-rated at 700N. Hopefully will do!

  Are you sure? yes | no

Dan Maloney wrote 06/02/2020 at 20:28 point

Haven't seen that design before. Here in the US, most dishwashers seem to have a mechanical latch. Interesting how designs vary regionally.

Good luck!

  Are you sure? yes | no

Bharbour wrote 10/31/2020 at 02:18 point

We also have a Bosch in the US. It does not have a separate lock mechanism. Ours does not beep when done, the display shows 00 for the time and that is the end of it

  Are you sure? yes | no

Ivan Stepaniuk wrote 11/03/2020 at 10:35 point

We have both types around, but for new kitchens this side of the Atlantic, the so called "integrated" models are often used. The dishwasher comes with no latch because you have to attach an MDF/wood panel to the front of it so it looks the same as the rest of your kitchen furniture. The handle is then a regular cupboard/cabinet handle. The latch is replaced with a catching mechanism that makes closing lighter than opening (not the best for my purpose, BTW)

  Are you sure? yes | no

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