Op Amp Question (Need to amp DAC Output)

[iso9001]

I'm sending a signal (voltage) from my DAC to an op amp, I need it to be the same voltage when done (ie: if i have 4.7V leaving the dac, i need 4.7V coming out of the amp, but with more power... I just picked 4.7V as a high example, I know most amps dont go near rail to rail, but i might be able to supply it w/ 12V if NEEDED, But I think most of my signals will be from 1.0 to 3.0)

Do i use a LM386 or LM741 ??? (I read somwhere one is voltage and the other is power...)

I tried hooking these up earlier today, But i think i hooked them up wrong cause my dac signal seemed to get 'lost' and both just ouput Vdd... (not what i want)

I also read somwhere that you'de want a ~10k R on the input from the dac... But I cant figure out WHY... My dac is only putting out .5mA, and the OpAmp can take more then that in... What is the R for ?

Thanks!

 

[crust]

You want to configure your op-amp as a voltage follower. You can just tie the inverting input to the output (i.e. make Rf=0) and feed your signal into the non-inverting input. The 741 would not be the best choice for a precision system, but for most lab bench purposes it works just fine. You may run into issues though b/c you normally need a couple of volts between your rails and your maximum output.