Can''t get op-amp (LM358) to work.
Archiver
Posts: 46,084
I don't think that there is nothing wrong with the OpAmp.
I don't know what you mean by the reference voltage, but
I have seen this before.
What voltage are you powering the OpAmp with, I suspect that
you are operating at the system extremeties.
Remember that if you power up an OpAmp with 5.0 Volts that
actual operating range is %20 of that which means that the
maximum output of the OpAmp is 4.0 Volts.
Let me know if that helps
> Hello,
>
> I am new to this embedded control stuff, and I am working on my own. And
> I have this problem.... I am working with the Industrial control book,
> and I am trying to implement the 1st ckt in chapter 2.
>
> The LM358 has it's input tied to a phototransistor whose voltage is
> switching between 4.77 and 4.13 V (measured using multimeter). The
> reference voltage is around 4.52 V. The output of the op-amp remains
> unchanged at around 3.7 V. I tried both the op-amps in the LM358. No
> luck.
>
> Is the chip bad ? Is there something I should try before getting a new
> chip ?
>
> Thanks a lot.
> Subhrajit
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
I don't know what you mean by the reference voltage, but
I have seen this before.
What voltage are you powering the OpAmp with, I suspect that
you are operating at the system extremeties.
Remember that if you power up an OpAmp with 5.0 Volts that
actual operating range is %20 of that which means that the
maximum output of the OpAmp is 4.0 Volts.
Let me know if that helps
> Hello,
>
> I am new to this embedded control stuff, and I am working on my own. And
> I have this problem.... I am working with the Industrial control book,
> and I am trying to implement the 1st ckt in chapter 2.
>
> The LM358 has it's input tied to a phototransistor whose voltage is
> switching between 4.77 and 4.13 V (measured using multimeter). The
> reference voltage is around 4.52 V. The output of the op-amp remains
> unchanged at around 3.7 V. I tried both the op-amps in the LM358. No
> luck.
>
> Is the chip bad ? Is there something I should try before getting a new
> chip ?
>
> Thanks a lot.
> Subhrajit
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject
> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/