Hold function for Telephone Electronic Circuit

From CircuitsArchive

 
   +-------+------+      R1 = 2.2K
   |       |      |      R2 = 1 K
 -| SW     R      |      R3 = 47 ohms
   |       1      |      SCR = 2N5064, TIC47, or MCR104
   |       |      |
   R      LED     |               Well, that's it, just remember that
   2       |      |               the cathode of both the SCR and the
   |       |      +- RING (Red)   LED are towards the bottom.
   +------SCR
   |       |      +- TIP (Green)
   R       |      |
   3       |      |
   |       |      |
   +-------+------+
 

Sources

• figment[at]wam.umd.edu