question about energy consumption

[drk]

Hi, im thinking about building a preamp in my guitar with some gain stages using or a 741opamp, or a couple of npn transistors(or jfets).
and i was wondering, is there much difference in the energy used between a circuit with transistors, or one with opamp? as this preamp would be powered with a battery, should i have any concern about that?

thanks

[solderman]

Hi
No, I don think you have to worry at all. I use one 200 mA BOSS wallvart to drive my effects  (12 pc at the moment) and II haven't passed 100 mA yet)
When I messure the effects they are rearly over ten, mots between 3-7 mA if they are dist and a bit more for Chorus and such..
Here You have a page as a reference.

http://www.stinkfoot.se/andreas/diy/power/list.htm

//Solderman

[R.G.]

The biggest difference in power is usually whether or not LEDs are used. An LED in a pedal often eats as much power as the whole rest of the circuit put together.

[drk]

ok, got it 
thanks

[Steben]

Preamp discrete (transistors, BJT, FETs...) are easy to design with low power. The "Mini-booster" (J Orman) is a very gainy stage with very little current consumption. ( <<<1mA )
One Opamp stage usually uses a couple of mAmps on its own - 9V battery will die easily after +/- 100 hours - although there are low power opamps (TL06xxxx series, 2252 series, ...).