Triple Bi-directional Switch

Triple Bi-directional Switch

go here for the Triple Bi-directional Router

This module is a variation on the 1973 Classic Serge Triple Bi-directional Router, and the 1975 Bi-directional Quad Switch modules.


The schematic of Bi-directional Quad Switch module.

Bi-directional Quad Switch.
This version of the circuit adds a 4013 as a two bit binary counter, and some pre-wiring to form a one to four multiplexer/demultiplexer.

Construction


The component overlay for the VER1.0 PCB. Click here for an enlarged, printable version. Print at 300dpi.

If you are planning to use it with 6.3mm or 3.5mm jacks, the common of these jacks should be wired to 0V/GND as usual. Just solder the return wire to the (unused) center pins of the power connector.

We would suggest powering the module for the first time without any chips in it and checking the voltage between the emitters of the two regulating transistors (BC547 and BC557). If this voltage is over 15 volts, you will need to change the values of the resistors in the voltage divider.

Bi-directional Quad Switch


The wiring required to use the PCB as a Bi-directional Quad Switch.
Click here for an enlarged, printable version. Print at 300dpi.

When building the Bi-directional Quad Switch, install all parts except for the 22k resistors. Wires need to be run from the pads marked M, N and O to one pad of each of the empty 22k resistor locations. See the photo above. You also need to link pads C to L and B to H complete the routing. In this configuration, the I input is the only one used. A positive gate or trigger signal will advance the switch to the next input/output.

Bi-directional Quad Switch

As the gates are in series, some the protection resistors are not required, but were present on the original Serge version, effectively doubling the resistance of the switch. You can replace these extra resistors with links. On the prototype, I shorted out the extra resistors on the rear of the PCB as shown above.

Wiring the CGS88 Bi-directional Quad Switch.
The original had two directly linked jacks for each of the input and output connections.

Set Up

There is no setup.

Notes:

  • The trigger/gate voltage is somewhat higher than used on CGS modules. Increasing the value of the upper resistor (8k2) in the reverence voltage divider will lower the detection point.
  • The module will work on +/-12 volts or with modification, on +/-15 volts.
  • PCB info: 6" x 1" with 3mm mounting holes 0.15" in from the edges.

Parts list

This is a guide only. Parts needed will vary with individual constructor's needs.

Article, art & design copyright by Ken Stone