Problems with bipolar supply (max1044) - Tremolo

[bryantabuteau]

Hi, i'm in the process of converting my anderton tremolo over to the max1044/similar chip for bipolar supply.  I wired it up accordign to the geofex doc...
http://www.geofex.com/circuits/+9_to_-9.htm
I'm confused about a few things...

The different sized triangles on the diagram for stereo jack switching...do these indicate a different ground connection?  From reading the text, I assume it does.  So I've got my battery -ve and the grounds from the max1044 chip connected, and the signal grounds all connected up to the input jack (and the base of the transistor when a plug is inserted).  I can't quite understand where the board gets its ground reference from.
If someone could give me an idea of which grounds are to connected where, It would be greatly appreciated.  Combined with stero jack input switching and a dc jack switching the battery in and out, i'm a bit confused.

[The Tone God]

If your talking about the Craig Anderton tremolo why not save yourself alot of pain and run it in single supply ? All you would have to do is mod the opamp sections.

Andrew

[bryantabuteau]

well, the pain and trouble have almost passed  it works off dual batteries, and i've made up the max1044 circuit already.  just tyring to figure it out.  Maybe the next one I'll try with plain ol 9v, but then again, I wouldn't know where to start modifying things.

[The Tone God]

Maybe the next one I'll try with plain ol 9v, but then again, I wouldn't know where to start modifying things.

You just need to attach the battery ground to everything listed as negative. Then take the two opamp non-inverting inputs and feed them from a voltage divder network. Pretty simple actually.

Read the following for a better explanation:

Opamp-eration

Andrew

[onboard]

Hey, c'mon...the question was about getting the MAX1044 running (although virtual grounding with a 1/2 supply reference voltage *is* neat-o)  

The different sized triangles on the diagram for stereo jack switching...do these indicate a different ground connection?

:wink: I just looked at the diagram and I know what you mean.  I'ld say all the triangles, big and little, are ground.  

Negative battery terminal, input sleeve, max1044 pin 3, and the positve side of C2 are all connected to the same ground plane.

Hope it works out for you!

[bryantabuteau]

thanks guys.  I WILL read up on that other stuff.  Will be handy to know, but for now, i'll just do a quick rewire and see what happens.

[onboard]

Just to be sure, the max1044 pin 5 is your board's negative supply, and pin 8 is positive supply - no battery connections there.  That might be obvious, but might as well be obvious...

Let everyone know how it turns out - don't know how many folks are using that particular trick

[bryantabuteau]

well, I connected all the grounds and switched on the -ve of the battery, and it seems to be working sweet, but i'd still like someone to explain a little about why the switching transistor is there in the circuit.  The article explains that the max1044 creates surges on the ground that its using, and that this shouldn't be connected to the circuit ground or you'd get a whine, hence why its designed with a switching transistor.  but the way i have it with all the grounds connected anyway, i think i've just bypassed any effect that transistor was going to have, so i might as well just connect the 9v straight to the max1044.  Out of my league unfortunately.  I have a working circuit, so I'm happy, but I was going to wire up a max1044 circuit for my transformer isolated A/B/Y box that runs on 2 batteries, and before i do that, it would be handy to know whether the little transistor switching circuit is needed, or exactly what it achieves.

[bryantabuteau]

bump - anybody care to explain how the switching works in relation to keeping whine off the ground?  RG?

[Torchy]

crp

[bryantabuteau]

Okay, had a look at that, and it confirmed that I'm still confused.
I traced the pcb stuff out, and I understand that part of the circuit, but the text still says to keep the -ve battery wire off the signal ground, and It seems to be attaching the -ve battery wire to 'a' ground, I think it may be that I am confused as to the 'signal' ground and other grounds.  Normally I attached them all together, In this case I don't think I should.   What parts are connected to the -ve battery wire ground, and what parts are connected to the signal ground?  and how is the signal ground referenced?
going round in circles I think