Operational amplifier 741

[Mat22]

Hello,

I have 0,02 V AC, can I amplifie it with 741 operationa amplifier 741 to 6 V'

thanks

 

[unclejed613]

quick answer, yes

long answer.... (you should have the data sheet) the required gain is 6/0.02=300. also, because of a frequency dependent limitation on voltage swing, the frequency must be less than 15khz (look at the voltage swing vs frequency, and assuming you are talking 6Vrms, the required voltage swing is 1.414*6=+/-8.5). if you need the data sheet, it is here: https://www.electro-tech-online.com/custompdfs/2013/06/ua741.pdf

always start with the data sheet, you will need to ask fewer questions.

as to why it has to be a 741, it's either a homework question, or you have a very old book on op amps... 741 op amps are about the furthest you can get from an "ideal" op amp (maybe that's the reason school courses still use them?), have horrible frequency response, slew rates, noise, input offsets.... the list goes on....

 

[Mat22]

Ok,
So, I have AC voltage from small current transformer for monitoring 230 V AC line 50 Hz
- 0,02V. I want to amplifie it to 6 V and use it with Pic microcontroler. Which op amp do you suggest?
Thanks

 

[MikeMl]

Ok,
So, I have AC voltage from small current transformer for monitoring 230 V AC line 50 Hz
- 0,02V. I want to amplifie it to 6 V and use it with Pic microcontroler. Which op amp do you suggest?
Thanks

One from our forum, but unfortunately, the attachments are missing due to a hard disc crash...

Not a new problem

Another

 

[alec_t]

If you are only monitoring the presence of mains voltage, as distinct from measuring current in a mains-connected appliance, why not just use a 6V (or whatever) transformer and avoid the need for an opamp?

 

[Mat22]

If you are only monitoring the presence of mains voltage, as distinct from measuring current in a mains-connected appliance, why not just use a 6V (or whatever) transformer and avoid the need for an opamp?

Physical implementation of transformer is not possible in this case, I have to use specific current transformer

 

[EternityForest]

Are you sure you want to amplify to 6V? All of the PICs I know of except the HV ones run at 5.5V or less and even the HV ones work by having an internal 5.5V or less reg. If you are putting 6V directly into a 5V pic be sure to use a big resistor.

Quite a few PICs have internal comparators, you could look into using one of those instead of an op amp.