I'm relatively new to the world of electronics, and I've stumbled upon a schematic diagram that's been giving me quite a headache. I was hoping some of you experienced folks could lend me a hand in deciphering it.

 

This is a useless Schematic.
It will continuously oscillate, and not provide any useful function.
( Unless it's supposed to provide some sort of special PWM-Output )

Why don't You simply state what You are trying to achieve, ( in detail ) ?
.
.
.

 

This is a useless Schematic.
It will continuously oscillate, and not provide any useful function.
( Unless it's supposed to provide some sort of special PWM-Output )

Why don't You simply state what You are trying to achieve, ( in detail ) ?
.
.
.

hello sir and thank you for reply . i want to creat a baord with an atmega1280 chip and a k thermoucoples and ihave to amplifie the signal from the k thermou so it can be read by the atmega

 

The symbol is a type k thermocouple with grounded junction

 

hello sir and thank you for reply . i want to creat a baord with an atmega1280 chip and a k thermoucoples and ihave to amplifie the signal from the k thermou so it can be read by the atmega

If you want to do this easily and quickly use a MAX31855 IC connected to the ATmega1280 via I2C 2-wire interface . Don't waste your time, money and sanity messing around with discrete op-amp & ADC solutions, you'll be in a world of non-linearity and drift and the chances of getting a useful reading are minimal... been there, done it.;..

 

This is a useless Schematic. It will continuously oscillate...

why?

for oscillation positive feedback is needed. this circuit uses negative feedback. am i missing something?

 

am i missing something?

No.

R338 is not part of a positive feedback loop. Don't let the terrible schematic technique confuse things. R338 is the normal connection from the non-inverting input to GND is a fully-differential opamp circuit.

Also, one end of C305, C306, and all four diodes is grounded. All of that is a single-pole lowpass filter with bipolar transient protection clamping to approx. 0.2 V.

ak

 

All, the mods have moved the TS' other thread on this subject to Homework Help so further discussion purely academic