Pushing smartphone side buttons  - Page 1
Forum section: electronics / beginners

author: Boogami
author_rank: Contributor
timestamp: February 01, 2019, 04:49:35 pm
content: Hello,I want to push buttons on the side of the phone (volume buttons, power button) using some sort of actuator. I've tested a small open frame push solenoid at 12V but it doesn't have the necessary force to push the buttons. Do you know any solution that can do this thing? Also I am thinking about using a micro servo but I want something that doesn't make so much noise.Thank you.

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 01, 2019, 06:13:06 pm
content: Quote from: Boogami on February 01, 2019, 04:49:35 pmSure, servo with a cam would work. Not much noise IMO.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 01, 2019, 06:19:50 pm
content: I assume you can't modify the phone? Otherwise you could attach your inputs directly to the button pads.

author: soldar
author_rank: Super Contributor
timestamp: February 01, 2019, 06:31:23 pm
content: Quote from: Boogami on February 01, 2019, 04:49:35 pmUm... bigger solenoid?Seriously, how much force and travel do you need? Because some solenoids I have used would crush your phone easily.

author: Boogami
author_rank: Contributor
timestamp: February 01, 2019, 06:33:21 pm
content: Quote from: Mr. Scram on February 01, 2019, 06:19:50 pmYes, that is true. The phone is fixed on a surface and I want to mechanically interact with the buttons. Model of the phone can be changed so I can't modify the phone.

author: Ian.M
author_rank: Super Contributor
timestamp: February 01, 2019, 06:54:40 pm
content: I would suggest levers (e.g. bell cranks) to reduce the 'throw' and increase the available force the solonoid can provide.However a first step in any solution would be to determine the operating force required for the buttons. Glue a little rubber pad on the end of a bolt, and bluetak the head to the center of the platform of some digital scales of at least 1g resolution. Zero the scales. Hold the phone sideways and press the button down on the end of the bolt, gently increasing the pressure till it operates. Note the weight readout at that point, repeat a few times and average, then convert the result to Newtons force using the conversion factor of 9.8 Newtons per Kg.

author: Boogami
author_rank: Contributor
timestamp: February 01, 2019, 07:25:38 pm
content: Quote from: Ian.M on February 01, 2019, 06:54:40 pmSo that was an interesting experiment, never thought about using a scale like that. I got an average of 230 g when the button starts to click which means I need 2.26 Newtons of force to operate the button.

author: Ian.M
author_rank: Super Contributor
timestamp: February 01, 2019, 07:53:01 pm
content: I'd double that to allow for different or worn out buttons and go for about 4 to 5 newtons force. What are the specifications of your solonoids?

author: Boogami
author_rank: Contributor
timestamp: February 01, 2019, 08:12:42 pm
content: Quote from: Ian.M on February 01, 2019, 07:53:01 pmI was using a solenoid with 1.17N and one with 0.58N (both operating at 12V), they are very weak compared to what I really need. And to be honest I went with smaller solenoids in size because I didn't want to use a huge solenoid for operating some tiny smartphone buttons. But I was wrong.

author: Buriedcode
author_rank: Super Contributor
timestamp: February 01, 2019, 08:25:49 pm
content: Whilst it will add mechanical complexity - nothing wrong with using a lever to amplify the force. The travel must be about 1mm max, so if your solenoid displacement is 5mm - there you go.