hi, we currently have a intercom system fitted on a job and the customer wants a extra doorbell at the back of the house which is triggered when the intercom button is pressed. i have soliered a wire on the switch of the intercom and of the activation switch on the wireless doorbell push button to activate the bell. the issue is ones i connect them up the doorbell stays on all the time. any ideas how to resolve this ? thanks

 

Without knowing how the two switches are each connected in their respective circuits (e.g.whether they are high-side or low-side switches, normally-closed or normally-open) it is difficult to suggest a foolproof way of doing what you want. We could make some guesses, but get it wrong and there could be circuit damage.
Any chance of posting schematics of the circuitry? Makes/models?