[ChrioN]

How do I do that? Where should the + and - of the wallwart go?

 

[DaKi][er]

To the positive and negative inputs on it.... exactly where the battery would have gone

 

[ChrioN]

actually it is a grado ra1 clone I got, but I figured that more peoples have experience with cmoys, they are basicaly the same.
Though there is one difference. The ra1 doesnt use resistors as a voltagedivider.

Therefore the battery + goes to + on opamp and to ground, and battery - goes to opamp - and ground....

Do I need a resistor voltage divider? Or should I connect the wallwart + to opamp + and ground and the same with wallwart -?

 

[ericj]

You need a rail splitter, preferrably, and you may or may not be happy with the results until you regulate it.

 

[jar]

Quote:

Originally Posted by ChrioN Do I need a resistor voltage divider? Or should I connect the wallwart + to opamp + and ground and the same with wallwart -?

If you connect wallwart + and wallwart - both to ground, you're gonna short out and blow up the wallwart. The RA-1 (and presumably your clone (which is ok if you built it for yourself, otherwise it's stealing from food out of the mouths of John Grado's family)) uses 2 batteries to create a +,-,GND supply. There are various ways to do this from your single supply wall-wart. Take a look at tangent's virtual ground page.

 

[ChrioN]

Ok, do I need the 220uF caps? Or can I just use 2 resistors?

 

[Pars]

Read Tangent's virtual ground page (link above). Look for the TLE2426...

 

[ChrioN]

But tle2426s are very expensive where I live...I hoped to get the amp going without one of those. Is it possible?

 

[Pars]

Read the link and you can answer your own questions... yes there are other ways.

 

[ChrioN]

I have been at tangentsoft many times before, I was hoping to get a quick answer here. Is it possible to make a railsplitter for a wallwart with just 2 resistors?

 

[Pars]

Quote:

Originally Posted by ChrioN I have been at tangentsoft many times before, I was hoping to get a quick answer here. Is it possible to make a railsplitter for a wallwart with just 2 resistors?

Same thing as powering it with a battery... with the same issues. It's also possible to make an active railsplitter with a few easily sourced and cheap parts...

 

[ChrioN]

does the voltagedividing resistors have to be very close to the opamp powerpins?

 

[Xakepa]

Quote:

Originally Posted by ChrioN does the voltagedividing resistors have to be very close to the opamp powerpins?

Not at all - on this one.

Yes, you can use resistors for a voltage splitter. If you're going to use a wallwart exclusively, current draw is not an issue. Just be reasonable with their values (not too low), match the resistors and check everything before putting the opamp

Good luck