# Schmitt Trigger - Astable Mutivibrator Op-amps

1. Feb 13, 2005

### logicalman

Who has the guts to do the problems given in the attached pdf file???

I would like the folks competent to solve them to do Prb. 2 and 3.

Thanks!

P.S. few weeks ago I had posted a file related to Op-amps but no fruitful help was gotten from this forum, eventhough I am posting this file.

Hoping I get some good suggestions on these problems.

#### Attached Files:

• ###### op-amp_problems.pdf
File size:
45.2 KB
Views:
88
2. Feb 13, 2005

### gnome

Testing to see how many flies you can catch with vinegar?

3. Feb 13, 2005

### logicalman

Well anyways, here's what I've thought

In a general Schmitt Trigger figure:

No resistor between Vin and the inverting input.
It has a positive feedback along with a resistor R_3,
The non-inverting input has constant 5VDC input which is V_ref, there is a resistor R_2 between V_ref souce and the non-inverting input.
non-inverting input is also connected to the ground along with the resistor R_1.

As in the fig. in the attached file of schmitt trigger...

Now, V+ depends on V_out. When V_in < V_ref then V_out switches to V+saturation otherwise V-saturation.

and V+(>) - V+(<) = (2 R_123 / 3)
( R_123 eq. of all the 3 resistors)

The thing is what values of resistors shall I use?
and whats the use of output current and the sink current?

#### Attached Files:

• ###### schmitt_trigger_fig.doc
File size:
19.5 KB
Views:
68
4. Feb 13, 2005

### ktpr2

You can't have people do your homework for you! Go back to your teacher!

5. Feb 13, 2005

### logicalman

if u can't post anything worthwhile then don't b.s. atleast.

6. Feb 13, 2005

### logicalman

It *seems* like I am posting way too "advanced" stuff in here.

7. Feb 14, 2005

### Curious3141

8. Feb 14, 2005

### logicalman

I did the same thing written in that post of yours except the way of finding input impedance.

Anyways, for the problems I've posted over here - I already did them.