what is a logic probe?
Did you knew what is a logic probe? In this article admin will share about how to make logic probe using led. But before making it you must know first what a logic probe is
logic probe is a tool that is used to check input or output condition in digital circuits
A logic probe is required when you check on the digital circuit such as an IC expecially for TTL or CMOS. The results can be seen from the logic probe is logic 1 and 0 or high and low conditions
You can make a logic probe using led 2 pieces so that each color will display condition 1 or 0
- convert common anode to common cathode and otherwise
- series and parallel resistor circuits
- create a toogle switch using ic 4013
how to make a logic probe using led and how does logic probe work?
To create a logic probe you requires 2 led this time admin using red and green color pal you can replace it with another color as you wish
read also articles what is LED and how does it work
in the following sequence red Led serves to display high or logic conditions 1 whereas the green led is used to display low or logic conditions 0
As if the red and green led simultaneously it means the pin that the detection is in a floating condition that is a condition that is prohibited in the digital circuit
condition high or condition 1 is condition where an input or Output is connected with Vcc or positive voltage where condition low or condition 0 is condition where an input or Output is connected with ground or negative voltage
examples of high conditions in digital circuits
examples of low conditions in digital circuits
Well logic probe is used to detect a certain point on the circuit whether it is logged high or low
led red lights indicate a point in high condition whereas if the green led is indicating that it is in low condition, if it is lit together then it is in a floating condition. For Logic probe then ground circuit with ground logic probe must be combined
Read also an article about what is DTMF and how does it work?
Logic probes in high-light red light conditions
Logic probe under low green light conditions
Please note that led has a working voltage of 2-3V so the above circuit can only be used to detect high and low conditions at 5V voltage
if you want the circuit can be used to detect voltage up to 12V or 15V then you can add 1K resistor at the input circuit to reduce the current
for article about resistor please read on article what is resistor and how does it work