I want to create a circuit where an SCR is fired whenever the comparator output goes high. I want to add a delay circuit, causing a delay of 2msec. (Using cap and resistor)
Whenever I'm connecting comparator output to SCR, SCR input gets flipped. Im not getting why it is happening like this.
Also, can a cap of .1uF and Res of 20k will do that? , I saw the pulse is not delayed when I did this. Please guide me through this.

 

Hi, can you rephrase your goal as a bullet list or flow chart? I'm not sure you need a SCR or the second op amp based on your description.

 

Hi, can you rephrase your goal as a bullet list or flow chart? I'm not sure you need a SCR or the second op amp based on your description.

Sure, Please find it attached below.
Is it what you mean?

 

Sure, Please find it attached below.
Is it what you mean?

Yes, I can work with this. I'll see what I can come up with when I get home.

As for the SCR, what load are you driving?

 

Yes, I can work with this. I'll see what I can come up with when I get home.

As for the SCR, what load are you driving?

I want to connect it with a relay. When Scr fires, relay will be activated.

Will be waiting for your reply

 

I want to connect it with a relay. When Scr fires, relay will be activated.

Will be waiting for your reply

Can you tell me more about the input pulse? I see the parameters you set in V3 of your schematic but I would like to understand how this relates to the 4-8V specification you gave in post #3 and why this is important.

 

Your SCR appears to short out the power supply. After that your reference voltage will be wrong and nothing will power your comparator.
An LT1017 can only source 250uA. Your SCR needs a gate current of 15mA. It's never going to trigger.

 

You can try attached circuit. The R1C1 sets the 2ms delay. The C2 sets trigger pulse width.

 

What’s the point of the delay? The relay is going to take a few milliseconds to close.

 

Can you tell me more about the input pulse? I see the parameters you set in V3 of your schematic but I would like to understand how this relates to the 4-8V specification you gave in post #3 and why this is important.

Okay so I was working on a complex schematic from which I have omitted some part to make it more understandable. I guess just to understand the functioning of an scr, we can omit the higher and lower threshold also.
My apologies for the late reply, i was busy with some other stuffs.

 

What’s the point of the delay? The relay is going to take a few milliseconds to close.

I added delay because scr might get fired because of some noise or voltage surges. I don't want the scr to fire if the surges are within the given time limit i.e; 2msec.

 

Your SCR appears to short out the power supply. After that your reference voltage will be wrong and nothing will power your comparator.
An LT1017 can only source 250uA. Your SCR needs a gate current of 15mA. It's never going to trigger.

Okay I will attach other comparator compatible with 15mA output current.