modification from hook switch to reed switch

Community PCB Design
1

Hello:

First of all, thanks in advance for any help on this question:

I have a traditional 4x4 keypad telephone which has a hook switch on it,

I plan to modify it from hook switch to reed switch, could you tell me how to modify it by using only one reed switch instead of two ?

Please take a look at the attached

Thanks

2

please take a look at the attached, the guy use only one reed switch to control the traditional hook switch , I don’t know how to do it by using only one reed switch, I do know how to do it by two reed switches though…

3

this is the original hook switch, there’re two blades on it, I have removed it from telephone board, I am getting stuck on how to control it by only one reed switch? any advice would be appreciated.

4

any update would be appreciated :oops: :oops: :oops:

5

Totally didn’t expect to find one of these type questions looking up stuff, but I’m trying to remember my schooling from 15 years ago and shoot an answer just because.

I’m not 100% sure, since is has been a decade and a half since I messed with phones, but I do believe there are two different circuits running through that switch, the ringer and talk battery. They do come in on the same line from the wall, but the ringer voltage is 90vac and the talk battery like something like 50dcv, and a simple filter circuit separates the two inside the phone. When the handset is ‘down’ or on hook, the ringer voltage is connected to the bell, so the phone can ring. When you pick up the handset, the ringer switch disconnects and the talk battery connects.

There are only two ways I can think of to make this work with a reed switch and you’d have to be tricky with both of them. One would be to replace the switch with two reed switches, one that opens in a magnetic field and one that closes (if I remember right, finding one that opens in a magnetic field can be hard, but I have seen one before… about 20+ years ago in a copy machine or typewriter). The other way to do it would be to use a DPDT relay to perform the task of toggling the switch, and use the talk battery via the reed switch on the coil of the relay to control the relay.

6

Hi, TropllHammer:

Thanks , I did solve it by two reed switches, but I saw a video on youtube where it seemed to be solved by only one reed switch as attached, any more advice would be appreciated, thanks