Introduction: Extend Your Door Bell

About: What started as a passion for the technology - computers and electronics has finally coalesced into a career spinning webs on the Net.
I have a large house with a living room and a bedroom located in the first floor. The door chime connected to the front door switch is located in the ground floor - nothing unusual in most homes. Every time people spend their time in the first floor, the door bell is never answered unless they have robotic ears.

To cut a long story short, it was agreed by the occupants of the house that something singular must be done about extending the range of the front door bell/chime. Drawing parallel connection to the existing line would be tedious and involve running cables in a concealed manner.

So the resident techie was expected to come up with a quick and dirty solution to this problem. A quick check on the Net revealed that there was no direct solution available south of 40 dollars. Eventually I ended up making a simple circuit which extended the front door bell range right to the first floor - all at the cost of less than 5 dollars with about one hour of time well spent.

Before we go further let us take a look at the parts and complexity involved in this simple little project.

Parts List:

1. 6 V Relay DPDT contacts rated at 5 A @ 240 V X 1 ( contacts can be 1 A and I used what was readily available)
2. 6 V or 9 V power supply Adapter with 500 mA output  X 1
3. 1000 μF/16V Electrolytic Capacitor X 1
4. Cordless Calling Bell X 1 ( Preferably with telescopic antenna at both the handset and the Ringer base unit)
5. Short length of hookup wire

Skill set: A bit of Soldering is required

Step 1:

Take a look at the Circuit Diagram given here. You need to assemble them as given here.

Details in the diagram:

a b - Connect to existing Door Bell/Chime in parallel
c d - solder connecting wires directly to the bell switch of the handset of the Cordless Calling Bell

So when someone rings a bell at  the front door, the regular existing Chime will ring normally. In addition it also supplies Mains power to the 6/9V mains supply unit which is wired to the relay coil as shown in the Diagram. The relay activates the normally open contacts to trigger the remote bell handset. The relay has the 1000 μFd electrolytic capacitor in parallel which extends the duration of the time the bell is pressed.

Step 2:

Check the soldering of the relay and the bell handset. Observe the polarity of the electrolytic capacitor. The + tag should go to the power supply's + output. Reassemble the door bell. I used Bluetak or any double sided tape to assemble the bell unit with the power supply unit and mount the assembly next to the existing door chime/bell.

Check the working of the unit by pressing the doorbell. Your remote bell should ring now.

You can mount the remote bell in the first floor. The unit I worked with has a decent range with the telescopic antenna extended. Normally these cheap remote cordless bells work around 450 MHz. So there is little possibility of this unit messing up your Wifi signals.