Triple Bi-directional Router

go here for the Bi-directional Switch

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

The TRIPLE BI-DIRECTIONAL ROUTER is a group of three switches each of which can route one input to either of two outputs, or either of two inputs to one output according to a pulse or control voltage level. Alternately, it can be assembled to sequentially route one input to one of four outputs, or one of four inputs to one output.

The switches are true bi-directional switches. You can feed signals through them in either direction.

Note that due to the limits of CMOS, it can switch signals that are up to about +/-7 volts.

A little on how it works:

The schematic of the Triple Bi-directional Router module.

Triple Bi-directional Router.
The module uses the CMOS "Toolkit" chip, the 4007 wired as FET bi-directional switches. An LM3900 is used to condition the incoming gate signals to control the switches. A simple regulator is used to position the circuitry mid way between the power rails, at the maximum voltage at which CMOS can run (15 volts). The fourth section of the LM3900 is a part of this regulator. Note that there is no 0V/GND connection to this module.

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.

When building the Triple Bi-directional Router version, simply do not install the components in the outlined area on the PCB.

Wiring the CGS88 is very straight forward. An optional manual-override switch is shown. Use a three position center-off single pole switch for each of the three sections of the router. The wiring shown replaces the direct wire for each control jack to the pads marked E, I and A.

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