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[SOLVED] non-Inverter Amplifier

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andihong

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hello, i want to make an inverter amplifier,

here my circuit


Vin : 5volt
Rf : 5k
Rg : 2k
IC : LM358

if we calculate it, it should be 16.5V right ? i tested it and just 4V shown on multitester.

correct me if i wrong..
thank you..
 

esp1

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hi,
What is the Input voltage on Vin.?
 

uday mehta

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what is your Vdd ?
 
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uday mehta

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then your op amp saturated at 5V.give +16 volts at Vcc and -16 volts at Vee(in case of ac input). or give more then 16 volts at Vcc and ground Vee(in case of dc input).
 
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andihong

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then your op amp saturated at 5V.give +16 volts at Vcc and -16 volts at Vee.
if i want to make the output around 12V, i have to modify in the resistor.
but if the output around 12V, i still need to give +16V at vcc and -16v Vee ?


but is there any Vee on IC358 ? or the grounding ?
 

uday mehta

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you can get max o/p equal(nearly) to your supply voltage only.
and yes Vee is also present in LM358. but in DC application you can connect it to ground.
 

andihong

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you can get max o/p equal(nearly) to your supply voltage only.
and yes Vee is also present in LM358. but in DC application you can connect it to ground.
ok thank you.. :D, i am going to try that.
 

betwixt

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errmmmm.....

Isn't the schematic for a NON invering amplifier? Which is correct, the title or the first line of the first post?

Brian.
 

andihong

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errmmmm.....

Isn't the schematic for a NON invering amplifier? Which is correct, the title or the first line of the first post?

Brian.
eh, non inverter, sorry for missunderstanding..

but it's already solved.. thanks.
 

Audioguru

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you can get max o/p equal(nearly) to your supply voltage only.
No. Please read the datasheet.
When the load current of an opamp in an LM358 is 5mA or less then its output is typically 1.2V less than its supply voltage. If the output current is 20mA then the output is typically 2V less than its supply voltage.

- - - Updated - - -

How can the output voltage of an opamp be more than its supply voltage? For an LM358 and most other opamps it is not even the same, it is less.
The first example with a +5V input and 5k and 2k resistors, the voltage gain is (5k/2k) + 1= 3.5 times (nobody makes a 5k resistor value) so if the supply is about +19.5V or more then the output will be +17.5V.
A non-inverting opamp in an LM358 does not need a negative supply voltage if its input never becomes negative. Most other opamps need to have a negative supply if their input and output must be 0V.
 
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