Hello,
I'm doing a comparator using LM393.
Input/output parameters:
inverting input: 20VAC (effective value)
non-inverting input: 0V (GND)
supply voltage: 3.3VDC
Expected behaviour:
0V - when Vin <0
3.3V - when Vin>0
My circuit looks like this:
![Clipboard01.jpg Clipboard01.jpg](https://www.electro-tech-online.com/data/attachments/48/48050-8c14363c3722627f552125b868d39cfd.jpg)
In PSpice everything looks fine:
![Clipboard02.jpg Clipboard02.jpg](https://www.electro-tech-online.com/data/attachments/48/48051-85717963dcc559b7a5ff6a60e101072e.jpg)
But real circuit doesn't work properly. It looks similar to this:
![Clipboard03.jpg Clipboard03.jpg](https://www.electro-tech-online.com/data/attachments/48/48052-14ccff1bd32bba252c048a5e128895d7.jpg)
I don't know in which exact moment of time there is high voltage (3.3 V), cause I have only one-channel oscilloscope.
I suppose this problem can be related with GND.
I will be grateful for any help.
Greetings,
Michal
I'm doing a comparator using LM393.
Input/output parameters:
inverting input: 20VAC (effective value)
non-inverting input: 0V (GND)
supply voltage: 3.3VDC
Expected behaviour:
0V - when Vin <0
3.3V - when Vin>0
My circuit looks like this:
![Clipboard01.jpg Clipboard01.jpg](https://www.electro-tech-online.com/data/attachments/48/48050-8c14363c3722627f552125b868d39cfd.jpg)
In PSpice everything looks fine:
![Clipboard02.jpg Clipboard02.jpg](https://www.electro-tech-online.com/data/attachments/48/48051-85717963dcc559b7a5ff6a60e101072e.jpg)
But real circuit doesn't work properly. It looks similar to this:
![Clipboard03.jpg Clipboard03.jpg](https://www.electro-tech-online.com/data/attachments/48/48052-14ccff1bd32bba252c048a5e128895d7.jpg)
I don't know in which exact moment of time there is high voltage (3.3 V), cause I have only one-channel oscilloscope.
I suppose this problem can be related with GND.
I will be grateful for any help.
Greetings,
Michal
Last edited: