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Years back - My mom's friend (half deaf) had trouble hearing her phone ring.
I decided to make a simple flasher to help her "see" the phone ring.

This is a modification of that project - this time using Bright RGB LEDs
with a rating of 15,000 mcd.
I decided this time I wanted a flasher that you would notice in a room even
if it was still daylight.

I found a compromise between being blinded and more than bright enough
at a current of 24ma per Bright (15000 mcd) RGB LED pair.

Above (Image #1) is a photo of the minimal components I used to construct  the circuit.

This picture (Image 1) shows the wiring of components and also photos of the
final in-box layout and resulting flash of the bright (15000 mcd) RGB LEDs
when connected to the phone line via the phone cord with RJ45 jack.


Step 1: PHONE-ALERT Construction


Image #2 above shows the Components and Tools needed to construct the PHONE-ALERT.


Step 2: The CIRCUIT

Image #3 above is the circuit I used to take the incoming Phone AC Ring Signal...
and provide a half wave rectified signal to the Relay coil which responds to the ring's resident frequency... (usually between 20 to 90 Hz).

Why use a relay ?
The result is the relay turning on and off at the frequency of the ring producing a loud "clicking" sound that can be compared to the spinning of a roulette wheel.

This repeating ON-OFF contact of the relay - in turn - causes the 9V circuit to produce a fast ring frequency response to provide a 24 ma "quick flash" current to each of the two strings of Bright RGB LEDs.

Step 3: Construction Notes


Refer to the Circuit Diagram above:

The 470 ohm resistor and the two diodes can be soldered directly to the relay coil contacts.
Make sure the diodes are correctly positioned.

The TIP(+ve) end wire of the phone cord can then be soldered to the other end of the resistor and the RING (-ve) end wire to the -ve (stripe) end of the diode opposite to the resistor.

The BRIGHT RGB LED (pairs) can be soldered separately with a 100 ohm resistor in series with each string.

Image #1 (above) shows what the two LED string pairs look like when linked together with the
(+ve) ends of the LEDs connected to the (+ve) of the 9V battery and the (-ve) LED series resistor ends connected to the "common" of the relay.

Step 4: SUMMARY

Maybe you know someone who is elderly who when reading or watching TV
is not always aware of when the phone is ringing.

This will get their attention. 

This little box may even come in handy for myself and family and friends soon
since we are all baby boomers and our hearing isn't getting any better.


<p>I made this and it works great....at home. When I plug it in at a friend's place, the LEDs come on straight away and the phone is engaged. We've unplugged everything in the entire house and only plugged the &quot;flasher&quot; in and it still activates as soon as it is plugged in. Any ideas?</p>
Great idea!

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