1
\$\begingroup\$

I'd like to create a small device that can tell when it's near another created device or sensor. When it detects the other device, it lights up an LED.

Maybe maximum detection range of a few feet. No need for any unique ID values or complex data exchange, just a simple "Yes I detect one, no I don't" sort of control.

Any suggestions on how this could be done in a low power, portable sort of way? Because its requirements are so simple, something like RFID seems overkill (even if it could be made to work).

\$\endgroup\$

1 Answer 1

1
\$\begingroup\$

You could use a simple Infra-red LED, and a photo diode. You may have to adjust the LED intensity with a potentiometer to calibrate the range.

This will sense proximity providing there is line-of-sight.

\$\endgroup\$
3
  • \$\begingroup\$ Hmm hadn't thought of IR. Have to think about the LOS thing and if that's an issue... \$\endgroup\$
    – Tim Holt
    Mar 30, 2011 at 20:55
  • \$\begingroup\$ Calling this good - thanks for that brain nudge I needed BG100! The first circuit on home.cogeco.ca/~rpaisley4/PhotoDetectors.html (lights when sensing) looks like it would do what I need. \$\endgroup\$
    – Tim Holt
    Mar 30, 2011 at 21:25
  • \$\begingroup\$ @Tim Holt: No problem... \$\endgroup\$
    – BG100
    Mar 30, 2011 at 21:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.