Can''t get op-amp (LM358) to work.
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Posts: 46,084
In a message dated 1/31/2003 7:52:31 PM Pacific Standard Time,
subhrajitb@h... writes:
> 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 ?
>
The op amp "sounds" like it is no good.......It should certainly switch based
on the information you provided.
However, many times there is a wiring error you may have overlooked 25
times.....ie, incorrect pins used.
You can go to google, search on LM358 and download a data sheet....
Good luck. The op-amp should definately be going between logic 0 and 1 as you
go above and below the reference of 4.52. Which condition is supposed to give
you the high or low also depends on the reference tied to the + or -
input.....
[noparse][[/noparse]Non-text portions of this message have been removed]
subhrajitb@h... writes:
> 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 ?
>
The op amp "sounds" like it is no good.......It should certainly switch based
on the information you provided.
However, many times there is a wiring error you may have overlooked 25
times.....ie, incorrect pins used.
You can go to google, search on LM358 and download a data sheet....
Good luck. The op-amp should definately be going between logic 0 and 1 as you
go above and below the reference of 4.52. Which condition is supposed to give
you the high or low also depends on the reference tied to the + or -
input.....
[noparse][[/noparse]Non-text portions of this message have been removed]