Close a circuit for a second to control a buzzer, to be powered & controlled via landline telephone

MisterBill2

Joined Jan 23, 2018
9,792
That will allow decoding the unlock command after the call gets answered and prevent incorrect unlocking. all that the system needs then is a phone line interface and a power supply.
 

Thread Starter

Moses123

Joined Jan 10, 2019
10
Use 2 of these (https://www.vikingelectronics.com/product_docs/DOD/406.pdf) in parallel.

Use terminals 6 and 7 of First to trigger your system
Connect 6 and 7 of the second to the telephone Lines.

When the Ist Ring is received, both the relays operate, 1 triggers your system, the second extends a loop to the exchange to trip further rings.
This seems like the solution, but as some have pointed out BEWARE of scam calls, so i'll have to stick with more technical solutions.
 

Thread Starter

Moses123

Joined Jan 10, 2019
10
This will activate the relay after a single digit is pressed, (that what i understood, that it doesn't activate after multiple digits are pressed,, it uses just a single digit). Hence making it easy for anybody that knows the phone number to guess the digit.

Alternative is to use a UP to detect ring and decode tone(s).
What's a UP?

These 2 seem like the most correct solution, but I have zero knowledge with arduino.
I have a raspberry Pi that i want to setup with RasPBX, & 1 extension should do exactly this what i want, but i gave up, as I got nowhere with it.
 

MisterBill2

Joined Jan 23, 2018
9,792
Knowing the phone number to call plus knowing the number to answer is the key. The one that I was going to use was a fax machine line, so the fax machine would answer the phone. The caller had to know to wait until the fax was done and then key in one number to unlock the door.
There are also all kinds of multiple number circuits that need more than one number to trigger them. That could make it very secure because it would be simple to have it hang up if the wrong number were entered.
You could use an old answering machine to answer the line instead of a fax machine, it would be a lot cheaper, since old answering machines are often available free.
 
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