, all the great god, I want to do with LM339 voltage comparator, as shown in figure, LM339 voltage 5 v, reference voltage IN1 - is 5 v. Why external inputs IN1 + at 0 v to 12 v switch, OUT1 don't have any change???????

CodePudding user response:

In general, the op-amp/comparator work no more than the voltage amplitude of the signal
Can pick up on IN1 - a resistance to the ground, a partial pressure resistance network, such as 4 v, then measure the waveform at

CodePudding user response:

Set the IN1 - at 2.5 V, IN2 by partial pressure will be 12 - & gt; 5 v

CodePudding user response:

Power supply voltage is 5 V. I pressed IN1 - set points 2.5 V, IN1 + 12 V input, OUT1 normal turnover happens, now the problem is the comparison of the input signal is greater than the power supply voltage to the chip have any damage? Now can work normally,

CodePudding user response:

Detailed look at the PDF manual, recommended input range 0 ~ VCC - 1.5

CodePudding user response:

First input is greater than the power supply for the comparator can say doesn't make sense, that is not, no matter to compare or benchmark, must be between 0 to 5,
Unless your 339 12 v power supply for the positive and negative, or what you said is wrong!