Compact phone splitter

This circuit can connect one telephone line in your home or work to multiple phones in parallel, without monitoring each other between the phones, avoiding unnecessary trouble. It also ensures that multiple phones can be connected in parallel to save money, which is very useful. value! You might as well make one and feel the joy of success. When wiring, connect the local line to L+/L- (pay attention to the voltage connection), and connect L1/L2 and L1"/L2" to two telephones respectively (not decomposable). Circuit diagram: 　　1. Working principle Assume that there are two telephones connected to the line, respectively connected to L and L". (We know that when the phone is in standby, there will be a DC voltage of 60V or 48V on the office line L depending on the switch. Shock When the phone is ringing, there will be an AC voltage of 95V or 75V. When the phone is off-hook, the line voltage will drop to about 10V due to the internal resistance of the phone. This unit is designed based on this principle.) Both phones are on standby, such as When a call comes, the AC current will pass through the above circuit to cause the two phones to ring. Assume that the extension on the L line picks up the phone first. The DC voltage on the line breaks down D2 in an instant and is applied to the control electrode of the BG1 thyristor through R2. When the voltage is triggered, BG1 turns on quickly, forming a DC path, and the phone can make normal calls. Since the line voltage is reduced at this time, the phone connected to L" will not hear any sound. This is if you want to go to the standby call, you can pick up the phone by dialing the numeric keys like a standby call (note: the phone must be in pulse dialing state). After hearing the ringing, pick up the phone. You can make calls after hanging up the online phone. The principle is the same. Adding unit circuits can expand to several extensions, but the maximum number should not exceed 10. 2. Component selection BG1 and BG2 are small unidirectional thyristors such as MCR100-6. In principle, the reverse breakdown voltage can be greater than 100V. D1 and D2 are 18V Zener diodes. The entire circuit can fit into a telephone wiring harness.