Board Layout for Strowger Candlestick


The Strowger PAX L427A with Automatic Electric type 24 dial is a nicely layed out telephone with terminals molded into its bakelite base. I did not want to alter any of the original wiring so I used two unused terminals. One was used to mount the antisidetone board and make the board connection to the transmitter. The other terminal was used to connect the receiver to the board. With this arrangement only two wires needed to be moved from their original terminals to an unused terminal, a change that can be easily changed back.


There is not much room in the base of this phone, and there is a wiring diagram glued to the bottom plate of the base. Preservation of the wiring diagram meant that the antisidetone board could not be adhered to the bottom plate with tape, so a small low-profile board had to be built that could be held in place by a counter sunk screw in an unused terminal. The transformer is recessed into the board to keep the profile as low as possible. Other than that, the board is similar to the other boards and was made by scoring two parallel lines on the the copper with an Xacto knife for each needed separation, then peeling the copper between the lines off of the circuit board. After the separations were made, the board was sanded, and then, tinned using a water-soluable solder paste. Components were surface mounted. A pigtail modular plug was used with a 20-inch cord, short enough so I would not have an unsightly wire lying around where the phone is displayed, but long enough to plug in to a counter-level socket for testing and demonstrating. Young people just don't believe these old phones still work.

Click on the photos below for construction details and photos.

Antisidetone Circuit

Board Artwork

Component Placement

Copyright Dale Thompson,
November 23, 2014 through
last revision on November 24, 2014