Cordless phone detector.

Thread Starter

nerdegutta

Joined Dec 15, 2009
2,676
Hi.

Which of these circuits would be best for detecting a cordless phone ringing?

The phones are Siemens Gigaset, I think... It's at my parents house.

I only need a circuit to detect the RF signal, the LED bit I hope I can manage to put in myself.
The volume on the cordless phone is not high enough, so I thought some flashing LEDs or something would draw the attention to the phone.

Also, I guess it is not recommended to breadboard this type of circuit for testing, due to all the stray capacitance and long legged components...

I've googled and youtubed a lot, and these circuits gets hit all the time.
 

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radiohead

Joined May 28, 2009
508
On the first circuit, do you have a component list? The IC is probably a 555.

The second circuit looks simple enough to breadboard, just to see roughly how it will perform.

The third circuit uses an op amp to amplify a weak signal and feed it to a 555 that drives an audio indicator. If all you require is a visual indication, you can omit the entire 555 circuit (C7 and everything to the right, except for the battery and switch).

If you want to build a prototype and don't want to breadboard it, you can use the dead bug (air circuit) or Manhattan style of circuit construction.
 

Thread Starter

nerdegutta

Joined Dec 15, 2009
2,676
On the first circuit, do you have a component list? The IC is probably a 555.
Yes it's a 555

The second circuit looks simple enough to breadboard, just to see roughly how it will perform.
Tried it, but it didn't do anything. :(


The third circuit uses an op amp to amplify a weak signal and feed it to a 555 that drives an audio indicator. If all you require is a visual indication, you can omit the entire 555 circuit (C7 and everything to the right, except for the battery and switch).
I only need visual indication. So this I might try.

If you want to build a prototype and don't want to breadboard it, you can use the dead bug (air circuit) or Manhattan style of circuit construction.
Now why didn't I think of that! :rolleyes:

But which of them would be best?
 
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