Hi All
I am trying to create a circuit at the output of a comparator, when the output of the comparator is high (3v3) I want and LED to turn on, but then I want this LED to remain on after this even regardless of any changes to the output of the comparator. Can someone please suggest what I could use, provide LTSpice simulations, any guidance help would be appreciated. I am also trying to reduce the amount of components I need to use as much as possible for this circuit if an IC already exists that already does this any suggestions would be greatly appreciated.

Kind Regards

Art

 

Hi All
I am trying to create a circuit at the output of a comparator, when the output of the comparator is high (3v3) I want and LED to turn on, but then I want this LED to remain on after this even regardless of any changes to the output of the comparator. Can someone please suggest what I could use, provide LTSpice simulations, any guidance help would be appreciated. I am also trying to reduce the amount of components I need to use as much as possible for this circuit if an IC already exists that already does this any suggestions would be greatly appreciated.

Kind Regards

Art

OpAmp with Flip-Flop.

 

Comparator plus latch (to be precise). But how will this latch be reset to switch the LED off or does it stay on forever?

 

Comparator plus latch (to be precise). But how will this latch be reset to switch the LED off or does it stay on forever?

Hi I want it to stay ON until I guess the whole power supply to everything in this circuit is reset

 

OpAmp with Flip-Flop.

Hi there would you mind providing a schematic of sorts? Could you also suggest what kind of Flip-Flop IC I should use?

 

Hi there would you mind providing a schematic of sorts? Could you also suggest what kind of Flip-Flop IC I should use?

What is your Vref for Comparator ?

 

What is your Vref for Comparator ?

around 3V

 

What is your Vref for Comparator ?

I'm using a digital comparator so Output is 3v3

 

What are you comparing? It may be possible to use one Schmitt trigger IC (e.g. CD4093) as both a comparator and a latch.

 

What are you comparing? It may be possible to use one Schmitt trigger IC (e.g. CD4093) as both a comparator and a latch.

So I am using this principle across various circuit it will be comparing voltage and current measurements that have a range of 0V-3V3, and I will be setting reference voltages myself, these comparators will be used as trips that go to a microcontroller but this particular uC only has three trip inputs so I'm ORING all these trips together, so that is why I was thinking of using LED's as a way to indicate which trip went off.

 

So I am using this principle across various circuit it will be comparing voltage and current measurements that have a range of 0V-3V3, and I will be setting reference voltages myself, these comparators will be used as trips that go to a microcontroller but this particular uC only has three trip inputs so I'm ORING all these trips together, so that is why I was thinking of using LED's as a way to indicate which trip went off.

Why don't you use ADC of uC (1 channel) with ADG731 (analog multiplexer spi interface).?

 

Why don't you use ADC of uC (1 channel) with ADG731 (analog multiplexer spi interface).?

I was considering that but kind of want to avoid that I would prefer something that was more of an indicator in terms of hardware i.e. an LED

 

I was considering that but kind of want to avoid that I would prefer something that was more of an indicator in terms of hardware i.e. an LED

Here is the quick circuit which I made. Hope this helps. Extract it using winrar or winzip and view the video in VLC Player.

 

If the negative-most range of the input signal (Vin) does not go below V- on the compariator + 1 diode drop, you can just use a diode to get a large amount of hysteresis to keep your LED on.I may be reading Alec_t's mind.

 

With my circuit use 1N4372A (3V zener).