LM741 amplifier

[KvR1021]

Hi

Is there any difference between using ±12v or 0v and 24v to supply the lm741 amplifier?

Thanks,

 

[KvR1021]

Also, i have built a vu meter with the LM3915 IC and i want to amplify my audio signal from my mp3 which is 300mV.
To how much should i amplify the voltage and why?
Is lm741 a good amplifier to use?

Thanks,

 

[davenn]

Hi

Is there any difference between using ±12v or 0v and 24v to supply the lm741 amplifier?

Thanks,

the datasheet tells all ... have a read ....
http://www.ti.com/lit/ds/symlink/lm741.pdf

 

[davenn]

Also, i have built a vu meter with the LM3915 IC and i want to amplify my audio signal from my mp3 which is 300mV.
To how much should i amplify the voltage and why?
Is lm741 a good amplifier to use?

Thanks,

300mV will probably almost overdrive the 3915 .... again check the datasheet

 

[KvR1021]

Hi

So ive tested the lm3915 vu meter circuit with a functiongenerator and it works perfectly.
When i want to use audio from my phone the circuit doesnt work.
If i want to amplify the signal using a non inverting amp, how much should the amplification be?
I know you can just lower reference voltage but i want to try it with an opamp.


Also ive read in the datasheet of lm741 that ±12v and 0v,24V is not the same. It has to be ±12v but i dont really understand why?

 

[EFDG]

Hi

Is there any difference between using ±12v or 0v and 24v to supply the lm741 amplifier?

yes split i.e. +- is used mostly for analog design.

 

[davenn]

Also ive read in the datasheet of lm741 that ±12v and 0v,24V is not the same. It has to be ±12v but i dont really understand why?

because the 741 requires a split rail supply not a single rail supply. There are a number of op-amps like this

 

[hevans1944]

It has to be ±12v but i dont really understand why?

Well, actually it doesn't have to be ±12 V DC. But it does get more complicated if you want to use a uni-polar power supply instead of a bi-polar power supply. Read this Texas Instrument Application Note and then come back here with more questions if you don't understand it.

Visit this site and study the schematic below. This is what you need to amplify your MP3 player output to drive the bar-graph VU-meter display. Note that you need coupling capacitors at both the input and the output because of the way the op-amp is biased for uni-polar operation.

 

[(*steve*)]

Also ive read in the datasheet of lm741 that ±12v and 0v,24V is not the same. It has to be ±12v but i dont really understand why?

The 741 will not know or care whether it is operating from 0V/24V, -12V/+12V, -24V/0V, or even -400V/-376V. If you maintain (say) a total of 24V difference between the supply rails and keep all the pins within other values relative to these you'll be fine.

HOWEVER quite often you will require a reference voltage. This is commonly mid-way between the supply voltages. This is where the subtle difference lies between a 24V supply and a +/-12V supply. The former has two connections, the latter three. The +/-12V supply also gives access to the common (or 0V or ground) rail which is mid-way between -12V and +12V.

There is no particular problem creating such a reference if you don't have one, but it is more work and is unlikely to be a system ground or reference level for signals so other aspects of your life can get difficult.

I'm sure the link you've been given will describe this in more detail.