How to trigger two doorbells that are on different frequencies - Page 1
Forum section: electronics / projects

author: lescro
author_rank: Newbie
timestamp: January 23, 2024, 08:49:13 am
content: I currently have a Honeywell Series 9 doorbell and push button that use the frequency 868Mhz. My daughter, who is deaf, needed a doorbell for her room. After reading that the Honeywell Series 3, 5 and 9 doorbells were all compatible, she purchased a Series 5 doorbell and push button. Unfortunately, it uses 916.5 Mhz. Is there a way to have one push button that triggers both doorbells?The details are:Description Model FrequencyHoneywell Wired/Wireless Dual Purpose Chime unit DW915XX 868 MHzHoneywell Wireless Push Button DCP311 868 MHzHoneywell Wireless Chime Unit and Wireless Push Button DC515NGA 916.5 MHzJust so you know, my daughter purchased two DC515NGA's. The idea was to have one for upstairs and one for downstairs. My unit has been used just for upstairs where the main living area is and where the front door is located.Any suggestions would be helpful.Thank you.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 23, 2024, 11:00:38 am
content: There are doorbell products on the market that allow multiple sounders or flashers to link with a single button.These honeywells can too... within the same product family. (series 5 or series 9)

author: lescro
author_rank: Newbie
timestamp: January 25, 2024, 06:35:00 am
content: Thank you for your reply.The problem is my front door push button is 868Mhz but my daughter's 2 doorbells are 916.8Mhz so they can't respond to the front door push button.My doorbell is 868Mhz so that works fine with the 868Mhz front door push button. Both series 3, 5 and 9 868 MHz systems and series 3, 5 and 9 916.8 systems allow multiple push buttons talking to multiple doorbells but you can't use an 868 MHz system with a 916.8 MHz system.Since a 868Mhz transmitter requires a 868Mhz receiver (similarly, for 916.8Mhz transmitter.) I need a work around eg push button that sends both 868 and 916.8Mhz signal.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 25, 2024, 08:19:04 am
content: Well, time to grab the soldering iron and add your own two-pole button to both transmitters.

author: Smokey
author_rank: Super Contributor
timestamp: January 25, 2024, 08:30:19 am
content: This reminds me of something like making a radio repeater from two HT set to different frequencies wired together crossing output and inputs between them.In this case, wire button2 signal to speaker1 signal (maintaining correct voltages and polarities and all that). When speaker1 goes off, it "pushes" the button2 signal on the other system.The other longer less physically intrusive answer is SDR and some code.

author: nfmax
author_rank: Super Contributor
timestamp: January 25, 2024, 09:08:53 am
content: I understand this device from RFXCOMhttp://www.rfxcom.com/epages/78165469.sf/en_GB/?ObjectPath=/Shops/78165469/Products/23103will receive the ActivLink protocol used by Honeywell doorbells, though I haven't tested it myself. Check with RFXCOM support if your 868MHz doorbell part number has been tested. You can connect it to a Raspbery Pi or some similar low-power device, and run the Node-RED graphical programming environmenthttps://nodered.org/. I am the author of a Node-RED 'node' that talks to RFXCOM deviceshttps://flows.nodered.org/node/node-red-contrib-rfxcom, and I am currently in the process of adding ActivLink protocol support (any day now!).Then create a Node-RED flow that listens for your doorbell, and when it receives a message, pulses a GPIO pin for one second. Connect a relay to this GPIO pin, and wire the relay contacts across the contacts of one of the 916.5MHz doorbell pushbuttons. That should work!I believe the 916.5MHz band is ANZ specific. RFXCOM make 868MHz and 433MHz band devices, mainly for European use (the software API is the same, so my node supports both), but no 916.5MHz version. Obviously, there are other combinations of software & hardware that might be used, but the overall approach should be similar.Or maybe your daughter might be able to return the 916.5MHz doorbells as not suitable for the task, and buy a compatible 868MHz replacement?

author: lescro
author_rank: Newbie
timestamp: March 14, 2024, 08:38:41 am
content: Good idea Jeroen3. My problem is that I can't seem to work out how to open the doorbell push button with my spudger. The space between the two plastic halves is very thin and I can't push the spudger in far enough to leverage it apart. It feels like they are glued together.I don't mind destroying my push button but my daughter doesn't want her push button damaged.

author: lescro
author_rank: Newbie
timestamp: March 14, 2024, 08:44:29 am
content: Thanks Smokey. Is there a basic circuit diagram for this? Obviously I would need to modify it for my situation.

author: lescro
author_rank: Newbie
timestamp: March 14, 2024, 08:57:49 am
content: Thanks nfmax for your reply. I think your approach might be too tricky for me 😔.