Hi there,

I've made a design that my group teacher has approved.
We're ordering parts through our university, and my LT1018 comparator is too pricey for the provided budget.
I've tested all the OP-amps and comparators included in LTSpice and have even imported some from PSpice models to give them a go.

However, no matter I find and try my signal out of the comparator get modified to the point where they are no longer usable within the original design.

Does anyone have a suggestion for a comparator that fits the datasheet of the 1018, has a similar signal out and is cheaper than what I am finding on Farnell (Out of stock), Elfa (out of stock) and Digikey?

 

hi hn,
Are you saying that these Opto input current and out current are acceptable usable values?
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hi hn,
This plot shows the LT1018 and a CA3140 version,.
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hi hn,
This version uses a LM319 as an option,
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What are the particular characteristics of the LT1018 do you need that other comparators can't provide?

 

You can post your question here too: https://www.pcbway.com/project/question/
Hopefully, you will get some more answers from PCB experts. Hope that will help.

 

Hi everyone, many thanks for your inputs. I tried some of your suggestions, but my class teacher has decided that we will use LM358 for everyone in the course to save on costs - since those suggested were also too expensive.
When I simulate that OP model (after having downloaded the .lib from texas instruments and inc. as a text file into spice, I get strange spikes at the non-inverting input of the OP amp.

Does anyone have any suggestions for how to fix this?

 

hi hn,
It works for me, change the settings in the control panel as shown, also note the change in .TRAN

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hi hn,
It works for me, change the settings in the control panel as shown, also note the change in .TRAN

E

View attachment 283002

View attachment 283000

I run LTspice on mac, so I have no idea what you changed heh.
I'll have a check on my stationary pc though. Many thanks for constantly answering and helping though.
I was worried that this change might cause issues, but I feel its safe now for me to start working in KiKad and order the other parts.