Analog and 3-1/2 digital display for +/- 199.9mV
This Circuit is a DPM or digital panel meter.
It has a analog bar graph display and a 3-1/2 digit
digital display. ICL7107 is used in the 200mV
U4A opamp LF353 amplifies the 200mV Full scale input
to the level required for the LM3914 display
circuit. D13-D14 are clamping protection diodes.
Adjust P1 trimpot for a reading of 1000 counts when
a 100.0 mV signal is fed at Vin. Adjust R8 trimpot
to get the 5th led to just turn on at 100mV
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3-1/2 digital display for +/- 199.9mV - del20009
A combination of digital and analog display is
helpful for quick decision making. Analog indicates
even from a distance the process dimension.
Human Brain understands analog better. The digital
is required to note down and record values for
determining a setpoint or performance of a system.
Sometimes a analog recorder with a ink-pen plot
against time is a very good way of process analysis.
Many systems are better studied using graphs not
tables and lists of numbers. A Computer based
data-logger gives greater power to this methods. You
can measure and plot graphs of various types and at
different points and for much longer periods.
Info useful to study and build this circuit.