I have breadboarded the LM393 and I can't get it to work at all.
I have a multi-turn pot supplying each of the non-inverting inputs and I've tried setting these from 2.3 volts to 4.6 volts. Then I supply a voltage of more than the non-inverting input 'reference'. The output never changes.
Rather than belaboring this issue does anyone have drawing of the LM393 that works? Please feel free to email me if possible to help me solve my misunderstanding of how this should work.
Are you including the pull up resistor on the output? Find a data sheet
-- these often give little circuits that work, although they universally omit the bypass caps.
Please help me understand what and how the 'pull up resistor' works.
I was able to get an LED to fire when the ref voltage is set below
2.5v and the input voltage is higher. Now all I need to do is to get the 'output' to trigger a relay.
Best regards, Spehro Pefhany
A quick AltaVista search of "pull up resistor" yielded 127,000 hits, with the top one being in Wikipedia -- it's short, but not too bad.
It sounds like you have a lot of very basic electronics to learn -- perhaps you should be asking for an appropriate book. Take a gander at the ARRL Handbook. Beyond that, I'm not sure what to suggest.
National's LM393 datasheet leaves nothing to be desired, at least not as far as wiring up an LM393 is concerned.
robert
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I guess I'll have to look for another one which is more 'up to date' than the one I have. The one I have on my shelf in the office at home is dated late '70s. Sure the fundamentals are the same but the book is at home and I'm away from home teaching a course in VB.NET. With the 'help' I was able to get from some of the extreemly helpful here I was able to get it working. Now all I need to do is to polish it up with some of the necessary additional components to make it more reliable.
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