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Wednesday, June 26, 2019

Digital Control for 8 Channel Analog Mux

A single Voltmeter or Digital Panel Meter DPM can monitor 8 Analog inputs from sensors or potentiometers using a Mux chip and creating simple digital controls for that.

The Pushbutton Logically Interlocked Controls are Auto and Manual. For Manual Setting Up and Down push-buttons select the channel. In the Auto mode the 4029 counter gets pulses from a 4093 Schmitt Nand Gate wired as an Oscillator. This circuit shown for six channels.

Industrial Process Control Circuits

Four pushbuttons on the front panel control the scanner.  One 4051 is used to multiplex 8 trimpots that hold the Analog Alarm Settings. The channel number in BCD is  translated to a LED channel Display with a 4511 chip.

Digital Control for 8 Channel Analog Mux

Pan and Zoom the Circuit for detailed Study here - Digital Control for Mux

The 6 or 8 LEDs decoded by the 4017 are placed just above each Trimpot. Select the channel and tweak the trimpot of the LED that is turned on. The output of U7 OP07 can be measured with a digital voltmeter to monitor the trimpot setting value.

Digital Timers, Counters and Clocks

This way all the channel alarm settings can be trimmed or tweaked by watching the voltmeter while turning it. Carbon or metal film presets should not be used for this. Something like Bourns ten turn trimpot. If changes made are more than ten times a month, you would rather use a bourns ten turn potentiometer.

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