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Md. Khairul Hasan Posts

Relay based two step counter

As I am working at an amusement park, our roller coaster ride suddenly had a problem. It never stopped, it is continuously running over and over. It was supposed to run on the loop two times then stop. So there is an emergency requirement of a two step counter, and I’ve made one by using three relays. here is the circuit diagram of it:

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Reading data to PC from a cheap multimeter – 4

To determine the segment pins, i had to remember the theory of seven segment. Seven segments usually has 7 LED for showing a single digit and one led for a dot(i dont care for it now). 7 pins to drive the segment 1 pin to drive the dot and one common anode or cathode. The LCD has 29 pins to be analyzed. It has 3 full functional digit and a semi segment to show only number 1. So it should need 7×3=21 pins for 3 digit and 2 pins for the last 1.

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Reading data to PC from a cheap multimeter – 3

The mighty DT830D multimeter.

DT830D Multimeter battery removed

After opened, the meter looks like this.

DT830D Meter Opened, not showing the back cover.

The LCD pads has 31 pins. Among those, 3 pins are shorted so making 29 pins. If i have to determine signal from 29 pins, an arduino uno will not be capable because it has only 20 useful pins and among those, 2 pins is reserved for serial txd and rxd.

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Reading data to PC from a cheap multimeter – 1

I was fascinated of getting data to PC to conditionally control other things, or making graphs to make the thing more understandable. There are RS232 capable, even bluetooth capable multimeter are available but those costs a fortune for hobbyists. Let’s assume, every hobbyists have enough time (to tinker with things) than money. I have researched on the internet, and found…

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