Trying to build a 2 doorbell indicator circuit with indicator lights and triggering Z-Wave

Thread Starter


Joined Dec 19, 2016

My house is a bit weird - split level with 2 front-doors, each on a different floor with a door-push feeding back to one central bell unit. The bell circuit is a standard wired one, powered by a Transformer rated at 10.3 Volts AC (1 amp) - although it actually outputs about 15 Volts for some reason.

To save me from rushing between floors trying to work out which door bell has been rung I decided to build a circuit that will:
- Light an LED for about 20 seconds (i.e. there will be 2 LEDs - 1 LED for each floor)
- Power a 2 input Z-Wave Sensor (9v), and trigger one of the inputs for each floor
- Power a 3v Wireless Doorpush, and trigger it (i.e. bypass the push) - which will wirelessly trigger standard plug-in bell receiver units around the house

On a breadboard this all works fine.

However, as soon as it is mounted in-situ - which is in a box behind the bell-unit:
- The LEDs sometimes come on correctly, sometimes both come on, sometimes none come on at all
- The Z-Wave circuit is sometimes triggered, sometimes not
- The Wireless doorpush trigger always works perfectly
- The main bell itself always works perfectly

I am sure that the transformer is putting out enough power - prior to the 9v regulator I get about 14v, and when everything is triggered I detect no drop whatsoever in any of the regulated supplies, although I am only using a regular multimeter.

I am wondering if this is:
- Interference from the main bell ringer solenoid - which sits in front of all the circuits, or,
- Could it be interference on the bell-push wires themselves (they are each 10-20m long, and quite thin), or,
- Have I designed the circuit badly (in particular I am wondering if it was a good idea for all triggering to be done through the door pushes)

As you will see from the Schematic - I've put connectors for all of the outputs to the ancilliary stuff like the bell-pushes, triggers, input and output supplies to leave just the meat of the thing - hopefully it is fairly clear though.

I'm new at this and got this far after a long process using all the helpful blogs and electronics tutorials available, but am now stumped and would be grateful if an expert can shed any light on the likely problem and how to fix it.

Many thanks in anticipation.




Joined Sep 24, 2015
My home, built in 1962, had the old standard electric doorbell. Ring one door and it would DING. Ring the other door and it would DING DONG. Being that old, and who knows how many times the wires have been trimmed due to the copper wires tarnishing over time and exposure to elements, the wires became too short to reuse. So now I have battery powered doorbells. Two units with two buttons. They are selectable as to what tune they play when a specific button is pressed. The front door has the elegant ring while the side door has the simple Ding Dong. And there are two units, one upstairs and one down. So wherever I am, if someone is at a door I know immediately which it is.

The ONLY hassle I'm having is with the front door button. It gets late day full direct sunshine and it seems to kill batteries every year. The side door has the same battery in it for 5 years now.

Thread Starter


Joined Dec 19, 2016
Thanks Tony. That would indeed solve the problem - but I also wanted the challenge of doing some beginner level electronics, so this seemed a good and handy little project to start me off.

I literally just finished having another go at it - I cut a hole in the side of the box and put all transmitting parts outside it (Z-Wave and wireless bell trigger), and I also put a 10uf capacitor across each of the bell-push connectors. It has given 100% result since that, but we'll see if it lasts. I'm guessing that the capacitors are cleaning up the signal from the bell-pushes - but I'd love to hear what somebody with more experience than me thinks.