Schmitt trigger switch ;help me...

[nirwara]

First, i really need anyone to help me..
And thanks a lot for those willing to help me here..

I understand about comparator but im confused whats different scmitt trigger and comparator..

 

[blueroomelectronics]

Have you tried Google?

 

[nirwara]

yah...
But not matched.. Only see schmitt trigger cct only..
I can't see schmitt trigger switch circuit proper way with good explanaition..

 

[ericgibbs]

yah...
But not matched.. Only see schmitt trigger cct only..
I can't see schmitt trigger switch circuit proper way with good explanaition..

Look at this forum link, see the notes regarding hysteresis.

https://www.electro-tech-online.com...-sensor.42159/?highlight=duarble+light+sensor

 

[on1aag]

Hi Nirwara,

A BJT, an opamp and a relay.

The most logical device to use as a schmitt trigger is
the opamp.

**broken link removed**

The output current of most opamps is a bit too low to
drive the "average" relay, that's where the BJT comes
in play. The opamp drives the BJT and the BJT drives
the relay.
And the relay drives the load, this load can be almost
anything, light bulbs, a motor, a heater . . .
In this case it's only a led.

on1aag.

 

[on1aag]

Hi Nirwara,

I think you should put a bit more effort in your work
otherwise you'll become as lazy and as stupid as I am.
You wouldn't want that to happen don't you ?

on1aag.

 

[nirwara]

yahh seem like that..
im still hunting..

 

[silvarblade]

if you are still not clear about a schmitts trigger then try wikipedia they ahve a short but simple description.

 

[Willbe]

Only one BJT, one OPAMP UA741 and a single power supply of 12V must be used.
For this project, the relay can be substituted by a light emitting diode (LED), that is, when the relay is on, the LED will light up.
[/COLOR]

He left out the series resistor for the LED, unless he is depending on the 741 output to limit the LED current.
A relay suppressor diode may not be needed here.

 

[blueroomelectronics]

Guess nobody want's to do the OPs homework assignment.

 

[nirwara]

thanks..
i've done this task now..
so enough here..

 

[Willbe]

Guess nobody want's to do the OPs homework assignment.

I wonder if he even read it before cutting & pasting.

If electronic design is difficult, and if "Adversity defines us.", I think he's been defined.