Automatic timer switch for assistive hearing loop device

Hi everyone,

I’m doing an engineering design project on a team at my university for senior citizens (who do or do not use hearing aids) who are the primary users and stakeholders. The whole idea is to make an induction loop that users can use when they switch their hearing aids to T-coil mode. Our design currently consists of a current amplifier (which we would like to run on batteries), copper wire loop, electret unidirectional microphones, and a hearing loop receiver (currently attached to headphones for testing purposes).

The primary need is for the battery pack to be turned off while the assembly is not in use - a two-hour window for lunch every day.
BIG IDEA: entire device (including Arduino) not drawing power at and before time t=0-, device drawing power between time t=0+ and t=2 hr

Two simple tasks that I would like the device to accomplish:

  1. when a person manually flips external switch - this starts a 2 hour clock in the Arduino and begins draw of power from batteries to amplifier
  2. after 2 hours, the Arduino turns off power to amplifier AND turns itself off so it is not draining the batteries

Keep in mind that for (1), I do not want the Arduino to be using any battery power before the switch is flipped on.

Any help with this project is appreciated (including code :slight_smile: )

Thanks.

Side note - no snarky comments (eg “figure it out yourself, engineer”)…

Hi, I think you need to do an overall Power Budget for this...

Major things we don't know:

  • What battery are you using? (Editorial: you won't know until you do a power budget)
  • Is the battery rechargeable? How often?
  • How much power is used when the system is active?

Snarkey Comment: Are these Senior lunches outdoors or in the wilderness? As a Senior I hope so, but... Why do you need battery power?

mattanderson_10: The whole idea is to make an induction loop that users can use when they switch their hearing aids to T-coil mode. Our design currently consists of a current amplifier

I had that idea too a few years ago. Even designed/manufactured a loop amp. Then realised that modern hearing-aids don't have a T-switch anymore. Leo..

Terry,

I'll give you solid numbers when I can find them. Specifically what should I look for?

We need it to run on batteries because the device poses a tripping hazard. It will lay on top of a table in their dining area. Not outdoors. They might catch zika...

This is the webpage with specs on the amplifier we are using. http://www.ampetronic.co/Products/Loop-Amplifiers/Room-Systems-to-1200m-sq/CLD1-Compact-Small-Area-Counter-Induction-Loop-Driver/CLD1

It takes 12 VDC at 1A max, and draws 130mA when all four mics we are using are in use. Hope this helps

Bump