Circuit for teleprompter bluetooth control

I’m working on building a teleprompter; it’s going to use a phone to display text, and I want to build a device to control it remotely. I’m thinking I’d take a Bluetooth keyboard apart and wire a timer circuit up to the down arrow, but I’ve run into a few questions/doubts with that:

  • Looking at the keyboard, I do see that there’s not a separate circuit from each key to the processor (which is as I’d expect); would I be able to use a transistor in place of the key switch? What kind of transistor should I use?
  • How can I determine the proper values and components to use? I want to be able to have it click anywhere from 4 times a second to once every 5 seconds, or something like that. (The keyboard runs on 3.7v, from looking at the battery.)

I’m a little familiar with electronics but haven’t done much as far as actually building a circuit like this. Maybe there’s a different way to do it? Like a programmable Bluetooth remote or something? I don’t know.

Thank you for contact Digikey Tech form , I not sure how to assist you on this question how you are using a cell phone ( if I am understanding you connectly you are going to use a cell Phone to read the text you have on it ?

You could use a photofet to replace the key.
https://www.digikey.com/en/products/detail/on-semiconductor/H11F1SR2M/1793947
Then drive the LED from the timer through a resistor. Note, that you’ll need to keep the pulse width narrow enough so that the keyboard does not emit key repeat.

Cheers,
Heke