Theremino multiplexer, a multiplier of inputs and outputs.

Theremino multiplexer, a multiplier of inputs and outputs for the Master.

The Theremino Multiplexer is a switch to eight locations, that accepts analog and digital signals of any voltage from 0 to 5 Volts. The signals can travel in both directions, from a Master output to eight actuators, or eight sensors to a single entrance to the Master.

Some examples – Connect up to eight Magnetometers to a single FastCounter. – Connect up to eight sensors to a single entrance Adc16. – Connect up to eight Relays in a single output DigOut.

Features The closed contact is like a very low resistor (less than 100 ohm resistor). The open contact is like a resistor high (about 50 Mega ohm). The total power consumption is a few micro Amperes. The leakage current is less than 100 Nano Amps. The switching time is less than 20 NS, transit time is 12 NS and parasitic capacities are a few pico Farad.

Have characteristics similar to those of a mechanical switch, so you can use it up to frequencies of 100 MHz and beyond.

Peculiarity of this adapter Before choosing this adapter for your applications, make sure that the sensors and actuators will run only one at a time. In addition to switch from one channel to another it will take some time (about 50 Ms to give time to the HAL to execute with certainty the switching and also some time, variable depending on the sensors, to stabilize the signal).

It is used to multiply the outlets (Digout, Servos or Pwm), make sure that the outputs are not enabled you are flying. Then, in case of actuator with high impedance input, to avoid accidental activations, you will have to add 10 k resistors to ground for each actuator. The resistors were not added to the basic design, because it would have prevented to read some sensors.

Use a 74HC4851 instead of the 74HC4051 The classic 4051, that has existed for decades, It works fine but, If possible, It would be better to use a 4851, which has a higher tolerance to disturbance on channels not connected (in the project download there are PDFs of both integrated). Both the ICS cost around half a Euro and the 4851 It is easily found by both Mouser that Farnell, so the only reason to use the 4051 is thus already someone in drawers. Who should buy them choose the 4851.

Project download The design of the PCB is completely in step 2.54 mm. Build it on a Breadboard thousand holes is really easy. You put the components from above, Turning the power strip and using small single wires (for example, cut by the resistors), to make the few necessary links.