# Power Gain

I created a circuit in the "EveryCircuit" Android app with an Op-Amp's + to 1V positive (Works with DC or AC) and 1V negative to GND. - (Op-Amp) is shorted with the output pin of the Op-Amp through a 10K Ohm Resistor. Then the - and GND is shorted with a 2K resistance.

It shows 6x Voltage Amplification.

So which Op-Amp should I use for this??

Do you want power gain as per you title or voltage gain as per your question?

Give us a link to EveryCircuit article.

Weedpharma

Its hard to be sure from the description, you seem to be describing a non-inverting amp
circuit. With a gain of 6 the 1V input will clip for a 5V opamp.

I presume you want to interwork with the Arduino, typically you would use a rail-to-rail
opamp able to run from 5V. If you are just learning circuits you have a wider choice
as you can have dual supplies (you mentioned AC).

Since opamps consume little current this is an occasion where two 9V batteries can be used,
one for +9V rail and one for -9V rail - then just about any opamp able to handle 18V single
supply or +/-9V supply.

Note modern low voltage rail-to-rail opamps often cannot run at this sort of voltage, and many
older opamps cannot work with just 5V - so check the datasheets.

Note that there is no actual difference between a single supply and dual supply opamp, its purely
a convention about what voltage level is called ground. With a single supply you often create
a signal ground at mid-rail (2.5V for the Arduino), using a voltage divider.

So what do you actually want to do?

It is actually a voltage gain I am looking for. I want to control high voltage devices through the Arduino.

Can I make a current gain too??

Maybe you should tell us what you are trying to accomplish. An Op Amp may not be the right tool for the job.

It is actually a voltage gain I am looking for. I want to control high voltage devices through the Arduino.

A “standard” op-amp can go to maybe 12 or 24V (with the appropriate 12 or 24V power supply) but they can’t handle “high voltage”.

The Arduino runs on 5V. I’m not sure about the Android, but it’s a low-voltage battery operated device too.

If you want to boost ~1V to ~5V linearly, an op-amp can do that. But, assuming this is for the Arduino’s input you may be able to use one of the Arduino’s analog inputs which can read down to about 1mV (0.001V) with the optional built-in 1.1V reference. So depending on what you’re trying to accomplish, you may not need amplification at all.

Can I make a current gain too??

Depends… A “standard” op-amp can put-out about as much current as the Arduino. But, if you need to boost a few microamps to a few milliamps, yes an op-amp can do that.

I created a circuit in the “EveryCircuit” Android app…

Can you give us a link to that so we know what you’re talking about? I have no idea how the Android device, the Arduino, or the op-amp “fit together” in your application.

Note that there is no actual difference between a single supply and dual supply opamp, its purely a convention about what voltage level is called ground.

Rare wisdom!

weedpharma:
Do you want power gain as per you title or voltage gain as per your question?

Give us a link to EveryCircuit article.

Weedpharma

EveryCircuit is an Android app in the Google Playstore. It is a simple circuit simulator.

I'll stick with LTSpice and Qucs though!

Russell.

Don't single ended op-amps have inputs that can be put at the rails without common-mode issues?

SagarDev:
It is actually a voltage gain I am looking for. I want to control high voltage devices through the Arduino.

Can I make a current gain too??

It is a voltage gain or simply the ability to turn on or off devices rated at a higher voltage? These are different things for the purpose of our answer.

The former is to amplify a small voltage (as in a low level signal) to get a larger usable voltage. The latter is simply the ability to turn the devices powered by a higher voltage, on or off.

Weedpharma

KeithRB:
Don't single ended op-amps have inputs that can be put at the rails without common-mode issues?

Only if you pick out a RRIO (rail-to-rail input/output) Op Amp. And even then, you have to read the specs. Some RRIO can only handle just barely to the rails, some can go a few volts below ground/V- in the inputs. None can truly provide full rail to rail output without some tricks.

created a circuit in the "EveryCircuit" Android app with an Op-Amp's + to 1V positive (Works with DC or AC) and 1V negative to GND. - (Op-Amp) is shorted with the output pin of the Op-Amp through a 10K Ohm Resistor. Then the - and GND is shorted with a 2K resistance.

It shows 6x Voltage Amplification.

So which Op-Amp should I use for this??

Come on, really ? You're asking us to choose a component without posting the schematic ?
Inverting/non-inverting ?