What kind of ESP controlled servo should I use to rotate a volume control safely?

ESPHome
24

Well you can save and restore the position just like with a servo. As long as its not moving at the moment power goes out, the position can be saved.

Also true about a driver but with the exception of the little bity sg90 servo, you would need a larger PSU for any other servo because 6-7v is the next size up. Not trying to argue, just saying. Its your deal, do it how you see fit.

I got these for a project a while back. Your project made me think of using a tensioned belt around the knob and then offsetting the stepper out of the way… idk thats where my mind goes sometimes…

Screenshot_20240807-094318_Amazon Shopping
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25

@stevemann I have ordered 6 SG 90 9G with 180 and 6 with 360 (180+180) movement, so then I will try the Volkswagen, thanks! :grin: And thanks for the tips on usage too!

26

I think I asked in another thread, but where are you located?

27

Mandal, in the extreme south of Norway. Or rather on Norway’s southern tip. Ten minutes in my boat, and the closest country ahead of it will be Denmark.

28

In my specific case it’s almost always moving and I also have blackouts frequently…
The next step up from sg90 is still still ok with 5V psu (MG996, Stall torque: 9.4kg/cm (4.8v), Stall current draw 1400mA)).

Nice belt pulleys you have, plenty of times needed those (small size) and never had on hands…

29

Oh ya, i forgot about those. For what its worth, ive had horrible experiences with those. Theyd be defective, not operational, stripped gears, some were supposed to be 180 deg and the internal pot wouldnt stop them so theyd strip gears and become continuous rotation servos on the first use… Maybe it was the vendor selling junk, idk but my experience was a nightmare.

Ive been using these since. They’re a little pricier but, never had an issue or regret with them.
https://www.amazon.com/Hiwonder-LD-220MG-Digital-Bearing-Aluminium/dp/B07CMBMWZW/ref=mp_s_a_1_3_pp?crid=FUFWF77SQRJE&dib=eyJ2IjoiMSJ9.0Y1LCBY9MH0Wwk1PfyWTH2p2rh9EdHkU97LGMJXd1EGQfxVOYtH4AMJtC-XNjyo8O2NccoTpn4982Qc8ZYY_xmtjM1tgElwXyYUHICgCccw4TtAG1zEB5Mba1KFY7UrkZxUfFO7rE91Ftco48OzY3OmuFCp2fAbUpyARnzPr0XQy4EiuVAjuO2bRZANq2ZXPORI-eFNgQQcVkqqLa5cRvw.XYcg1zqNE3yhQvi389v8AR4Ee6MWbHhA6iWVn1PDwfk&dib_tag=se&keywords=20kg+servo&qid=1723042737&sprefix=20kg+servo%2Caps%2C142&sr=8-3

30

Sorry for your experiences. There are so many variants, plastic geared, metal geared, MG995, MG996, MG996R, different turn degrees etc. Hit and miss to have good ones.
The one in your link is really nice, strong and silent, I used it once. But you need 6-8V 3A supply, so it’s not so “practical” for prototyping…

31

Ya, it sucked. You can get mg995 4 packs for pretty cheap. I get where your coming from with the <5v power requirements but, IMO its just a matter of the project and your willingness to improvise. Dev boards have 12/24v regulators now, there are very small buck converters available and many projects ive done, its not unusual to need 5v, 12v, and 110vAC so, it all depends on what someone is making.

32

Of course, but I try my best not to accumulate components in my drawers, so 7V3A bucks are not always on hands while 5V2A supplies I cand find in every corner of my house. I have one 1200W programmable supply for “whatever” situations, but often it’s not the most practical choice. Call me lazy!

33

I need to get on your “no clutter” program. I was just going through some of it today and i have organzers of esp boards, sensors, buttons, through hole components, transformers, multiple raspberry pi’s… thats several years worth but, its getting ridiculous. I just know as soon as i get rid of a bunch of it, ill be back online within a month buying this or that in a 5 pack and only need 1!

34

Or like me: When I downzised from a big house when the last of our kids moved out, I threw out a bunch of old stuff that I would “never ever” use again. I have bought a bit too many of those again now, six years later.

35

Nobody knows what I have inside my 3 meters wide closet in my work room. If I die, they think I’m some fucking freak. And I do my best every day to not accumulate stuff. But 1 board cost $5, 5 boards cost $7… What can you do…

36

I did that also, at least everything is organized better after that. But still I just found arduino uno ethernet shield from 2012 never opened…

37

I use some of the 20-25kg metal gear servos in my props, but the SG90s should be good for the volume control that @Mastiff is using. In fact, he may prefer theplastic gears in an ocean environment.

@Mastiff - have you looked at solid-state potentiometers?

38

I didn’t even know solid state potentiometers excisted. But finding one that works well with audio may be a hit and miss thing, not to mention that the price for three of those probably will be rather high.

39

One chip is $8.26 and has six potentiometers in it.

40

I stand corrected. Maybe I should try those next time, if they are suitable for audio. Do you know that? But they might still be a problem because I fought like heck to get all sources of noise away from the signal path (and that was a fight in an aluminium boat full of electronics!), and that’s why I wanted to use passive volume controls driven by a separate motor. That way there’s nothing that can come in and create noise. I actually had to use an USB sound card to get the audio out signal from the Pi in optical SPDIF and then use a headset amp to convert that back to line level. That took care of the noise on the line both on the boat and in the car (elecrtical car, so not much less that can make noise there).

41

I’ve never tried one, but I knew they were available. Newer audio gear uses optical rotary encoders instead of mechanical pots because the mechanical pots were prone to getting dirty and noisy.

42

I should get the sevos in a week or so, we’ll see how that works before I get more advanced. :grin:

43

Got them today. I am testing now, but there’s something weird: The first time I use the servo after a reboot of the ESP32 and press to minimum or maximum, it jumps far too fast to the midpoint, before it starts going slow, the way I want it to (I have 3 second transition) to the desired position. And it moves when I reboot the ESP32 as well. Are those two things avoidable? This is the code:

output:
  - platform: ledc
    pin: 21
    id: frontforsterkerpinne
    frequency: 50 Hz

servo:
  - id: frontforsterker
    output: frontforsterkerpinne
    auto_detach_time: 6s
    transition_length: 3s

button:
  - platform: template
    name: "Servo to minimum"
    on_press:
      - servo.write:
          id: frontforsterker
          level: -100.0%

  - platform: template
    name: "Servo to max"
    on_press:
      - servo.write:
          id: frontforsterker
          level: 100.0%

  - platform: template
    name: "Servo to middle position"
    on_press:
      - servo.write:
          id: frontforsterker
          level: 0%

Edit: I found a thread about that, seems like it’s unavoidable on these servos: ESPHome servo slow to the intial position? - #5 by zenzay42

I think it moves too fast for the volume control, it has too much inertia for this jump. I need to think about what I can do with that.

Edit 2: restore: true fixed that big jump. Maybe a relay on the 5V power supply to the servo can stop the jump when the ESP32 restarts. But that’s a much smaller jump as well.

Edit 3: Nope, then I got about the same jump when starting the move,so I’ll use it without that relay and hope that the flex in the connection will take care of that smal jump.