In the absence of available rooms on the PBX, you can establish a parallel phone. This issue is easily solved in the company with the consent of the principal party, but there is the possibility of callers to listen to each other. This can be avoided if we apply the proposed blocker. The device is made on the basis of industrial blocker coupled subscriber kit (Sak) ATSC 50/200, ATSC 100/2000.
The advantages of this scheme:
- the polarity of the telephone line does not matter;
- if one of the subscribers lifted the receiver from the telephone and began to dial, the other party may not hold the line;
- the device is not afraid of the surge line (thunderstorms), because it does not contain semiconductor devices, which is especially important for rural telephone networks.
Consider the order of lock work in different modes.
Outgoing calls. Let the subscriber 1 first picked up the receiver of the phone. The circuit is formed: terminal 3 - contact relay K2.1 - the relay coil K1 is the subscriber's telephone set 1 to the relay contacts K2.2 - terminal 4. This triggers the relay K1 and their contacts disconnects the subscriber from 2 phone lines.
When user 1 dials the number, the relay K1 does not have time to operate during short-term disconnection of the loop pulse contact telephone subscriber unit 1. After the call, the subscriber 1 hangs up the telephone, relay K1 releases, and the circuit reverts to its original state.
The operating procedure for a subscriber 2 is similar, only relay K2 and disables subscriber 1.
Incoming connection. When a call comes from the line relays K1 and K2 do not work as they are shunted by capacitors C1 and C2. The bell rings in the phones both parties. If you first picked up the receiver of the telephone device 1, the relay K1 and their contacts disables subscriber 2 from the line. If you first picked up the receiver of the subscriber 2, similarly to the relay K2 and disconnects the subscriber from line 1. After finishing the conversation, when a caller hangs up the telephone, let the corresponding relay, and the circuit reverts to its original state.
Relays K1 and K2 from industrial lock ATSC 50/200 (ATSC 100/2000). But these relays can be made independently, based on any relay type load tap-changers with break contacts. Standard relay has 2 windings. The winding 1-2 shorted to the best of slowing down when released.
As a body, you can use the case blockers ATSC 50/200, ATSC 100/2000 or to make any other. The relay should be mounted so that the plane of anchors relay is perpendicular to the surface of the earth.
The lock assembled on the proposed scheme is worked from the PBX 50/200 for almost a year, and failures were not.
Author: A. Domancy, Bobruisk; Publication: N. Bolshakov, rf.atnn.ru