About this Circuit
This digital voltmeter is ideal to use for measuring the
output voltage of your DC power supply. It includes a 3.5-digit LED display
with a negative voltage indicator. It measures DC voltages from 0 to 199.9V
with a resolution of 0.1V. The voltmeter is based on single ICL7107 chip and
may be fitted on a small 3cm x 7cm printed circuit board. The circuit should be
supplied with a 5V voltage supply and consumes only around 25mA.
Construction Notes
Brightness of the LED
display segments can be varied by adding or removing 1N4148 small signal diodes
that are connected in series. Use two 1N4148 diodes for higher LED display
brightness.
The use of 7805 5V
voltage regulator is highly recommended to prevent the damage of ICL7107, 7660
ICs and to extend the operating voltages.
220 Ohm resistor
should be connected to the PIN 4 on the first LED display.The voltmeter can
also be configured to measure different voltage ranges and display higher
voltage resolution. Replacing 1M with 100K resistor will allow to measure 0 -
19.99V voltages with 0.01V (10mV) accuracy.
Part's List:
1x - 220 Ohm Resistor
1x - 10K Resistor
1x - 15K Resistor
1x - 47K Resistor
1x - 100K Resistor
1x - 1M Resistor
1x 10K Pot
1x - 100pF Capacitor
1x - 10n Capacitor
1x - 100n Capacitor
1x - 220n Capacitor
1x - 470n Capacitor
2x - 10uF Capacitor
3x
- 1N4148 Diode
1x - ICL7107 IC
1x - 7660 IC
2x - MAN6910 2-digit
LED 7-segment Display
Calibration
Use 10K potentiometer to set the reference voltage between
PIN 35 and PIN 36 of the ICL7107 IC to 1V.
