kemalkemal
Member level 1
Hi all.
As you can see from the circuit schematic i try to send some data from PIC to PC(serial USB converter).
I used a max232. When i made the connection i saw that PIC-UART signal levels attenuate. So i decided to use a voltage follower after max 232 before serial-USB converter.
Although i tried many opamps i got the same result. Without load circuit behaves OK. I could get output what i gave from input of follower. But when i connect the serial USB converter (as a load) the output of voltage follower decays. Interesting thing is it can follow the negative side of the signal but cannot the positive side. BTW i supplied the opamp with +-14 volts (at my all trials).
This is my signal (from the board i designed) without load.
And this is what i got from output of follower after i connected the serial USB converter.
You can see the negative side OK but there is problem at following the positive side.
In order to see different opamp behaviours i used a signal generator and same simple voltage follower circuit.
LT1112. It is apparent that load affects both input(blue) and output(yellow).
opa07.
At all trials i got noise at positive side. Is there any thing you can suggest?
As you can see from the circuit schematic i try to send some data from PIC to PC(serial USB converter).
I used a max232. When i made the connection i saw that PIC-UART signal levels attenuate. So i decided to use a voltage follower after max 232 before serial-USB converter.
Although i tried many opamps i got the same result. Without load circuit behaves OK. I could get output what i gave from input of follower. But when i connect the serial USB converter (as a load) the output of voltage follower decays. Interesting thing is it can follow the negative side of the signal but cannot the positive side. BTW i supplied the opamp with +-14 volts (at my all trials).
This is my signal (from the board i designed) without load.
And this is what i got from output of follower after i connected the serial USB converter.
You can see the negative side OK but there is problem at following the positive side.
In order to see different opamp behaviours i used a signal generator and same simple voltage follower circuit.
LT1112. It is apparent that load affects both input(blue) and output(yellow).
opa07.
At all trials i got noise at positive side. Is there any thing you can suggest?
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