Please help me resolve why the Output suddenly drops to zero

Thread Starter

Vikram50517

Joined Jan 4, 2020
81
Man , i love all your replies m, atleast i understood how i should present my doubt so that you can help me better, laying out my circuit in simulators like LT spice gives a comparatively better description of the schematic that my verbal descriptions failed to do so.
:D

So informative ! I am a novice and i make so many silly mistakes makin a fool out of myself, but yeah this is how i learn so.. :)

I would try your out your suggestions first by correcting the op-amp thing and implementing it in a hardware circuit.

Thanks y'all
 
Last edited:

ericgibbs

Joined Jan 29, 2010
18,827
Salts,
Please read what the TS said: so i dont know it can be used as an amp)

Nowhere do I suggest he turns the Comp into an OPA.

BTW: it is not a hack, it is a commonly used option for a simple DC amp driving the second half of the dual configured as a Comp.
eg: LM35 > LM393 DC amp > LM393 as a Comp.

Please don't misquote me, there's a good chap.;)

E
 

MrSalts

Joined Apr 2, 2020
2,767
Salts,
Please read what the TS said: so i dont know it can be used as an amp)

Nowhere do I suggest he turns the Comp into an OPA.

BTW: it is not a hack, it is a commonly used option for a simple DC amp driving the second half of the dual configured as a Comp.

Please don't misquote me, there's a good chap.;)
It was an opinion, not a quote. I don't repeat bad advice.
You completely ignored the OPs offering of an LM358 which implied - TO A BEGINNER - that cobbling together a "DUAL DIFFERENTIAL COMPARITOR" as a high output impedance op amp (Fig 28) - higher than the recommended impedance than the spec for Arduino's ADC. If you say, some extra components (fig 30) can solve that because using 10 extra pieces is (easier/cheaper/better/more environmentally responsible/add your own... than just using an op amp? Why ignore the LM358?

Note: when an manufacturer doesn't include an application on a datasheet and only includes it on page 17 of a supplemental application note - it probably not the best idea. It's just an idea - or a grasping at straws idea to increase sales.

Be a good chap and tell the OP to use an OPA when he needs an OPA.
 

Audioguru again

Joined Oct 21, 2019
6,687
I suspect that the LM339 and LM393 comparators came first then National Semi decided to change them slightly into the LM324 and LM358 to make the world's first low current opamps. They probably said that nobody will notice the hiss, crossover distortion and missing high frequencies in heavy metal acid rock noises that most people listened to in those old days.
 
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