I have a doorbell button that is working as a contact. I want to use this contact button to operate a doorbell chime and a DoorFon system. If i connect just the doorbell to the button, the door chime works fine. If i connect just the DoorFon system to the button, the phones ring and operate just the way they are supposed to. If I parallel the doorbell and the DoorFon to the button, the system goes haywire and doesn't work at all...it just keeps ringing the DoorFon. What i want to do is use ONE button to operate TWO systems. I'm getting about 9-10.5V DC from the two wires from the doorbell AND, i'm getting about 2.5V DC from the DoorFon wires. What do i need to do to make these two systems work off of one button? Someone told me i need a zener diode or something to isolate the two voltages.... Please help! Thanks.
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