hi, guys
For the UA741CN, i connect it as a non-inverting amplfier,
and when there is no input voltage supply just only the Vcc and -Vcc
and the output it show high voltage...
should be in Zero or very small value right??
And, now im supplying 0.45V to the input pin of amplifier and no matter how much i changing the value of resistor with R1 and R2
the Output voltage is also same as the value that when there is no input voltage...
is it got any reasons will cause it??

 

Hello,

Did you have a look at this page of the eBook:

Divided feedback

Can you post a schematic so we can give our comments?

Bertus

 

http://www.google.com.my/imglanding...isch:1&start=14#tbnid=USRc9-6eewqZRM&start=21

this is the schematic that i use..

 

Assuming that you are using a dual power supply for your opamp, you will need to have a high valued resistor to ground on the positive input. Leaving the input open permits the input to float to an indeterminant voltage that is governed by the leakage current present at the input.

hgmjr

 

Hello,

Are you using a double powersupply?
What are the +Vcc and -Vcc values?

Bertus

 

yes, im using two power supply
with +5V and -5V to op amp

and i use +5V and -5V still cannot get the Vout i want
i increase it to +15V and -15V but it show the output voltage is 0V

 

What is the nature of the input signal that you are applying?

hgmjr

 

i am using DC supply

 

So when you apply, for example, a 1 volt DC signal to the positive input of the non-inverting opamp, your output remains at zero volts?

hgmjr

 

ya, it is happended at zero volts when i'm varying the positive input from 0V to 5V when i'm using +15V and -15V to op amp

but when i'm using +5V and -5V it shown 4.xxV

 

What are the values of R1 and R2 in your circuit?

hgmjr

 

What are the values of R1 and R2? Measure the output voltage when the i/p is grounded and see. Check these resources on Op-Amp.
http://creation-electronics.blogspot.com/2010/07/operational-amplifiers-opamps.html

 

R1 i'm using 70K ohm
R2 i'm using 10K ohm

then the output voltage measured is 4.31V

 

Have you rechecked your wiring to make sure that you have the proper connections?

hgmjr

 

ya, i'm rechecked again and again..

 

You may have a damaged opamp. Do you have another opamp you can try?

hgmjr

 

yes, i'm change with 3 op amps already
shown same result..

 

Either your opamp:

1. is damaged.
2. has one or more of its pins short to another pin.
3. has an open connection.

hgmjr

 

then from datasheet, it Vcc supply is give as +22V and -22V
then i need to follow it?will it spoil?

 

There is no need to power the opamp with anything more that +5 and -5 volts until you have determined what is keeping it from working. Raising the supply voltage could damage the part if something is wired wrong.

hgmjr