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Old 14th September 2003, 06:22 AM   #1
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Default dumbest question eV4R!

Ok, I'm a little embarrassed to ask this, but let me just get this straight.

But on this picture, all the IC's have a presumed 30V or whatever connection on the IC's? So if it was a 3886 then pins 1 & 5 (+) and 4 (-) on each IC would be connected to the PSU? I'm guessing this isn't pictured becuase it would be extraneous? Also IC1A and IC1B in the pictures have a + on the top one and a - on the bottom IC, but in fact both need to be connected...right??

Also I know alot of you guys like to do seperate transformers for each chip on single chip channels, but please god tell me your not putting individual torids in there?!?! Can you just connect them in series? like +[]- --> +[]- ---> +[]- , from one negative to the positive on the next? Assuming your using a large torid of course, like a 350VA+

Click the image to open in full size.

Ok how do you make pictures work on this freakin forum! This picture was in another thread. I tried the [img.] [/img] (without the "." obviously)
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Old 14th September 2003, 07:47 AM   #2
Nuuk is offline Nuuk  United Kingdom
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If I understand your question correctly, then the answer is yes, each chip needs a positive and negative voltage supply.

IC1a and IC1b require a supply of +/- 15 volts and the others require somewhere between +/-25-37 volts.

You could use just one transformer for the lot and then use a regulator to obtain the 15 volts supply. Personally, I would use a seperate transformer for the +/-15v supply and another for the other chips.
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Old 14th September 2003, 11:22 AM   #3
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Default Re: dumbest question eV4R!

Also IC1A and IC1B in the pictures have a + on the top one and a - on the bottom IC, but in fact both need to be connected...right??
Both opamps need to have supply rails connected of course, but the reference designators 1A and 1B mean they are both together in the same (probably) 8 pin package. Almost all dual 8 pin opamps have pin 4 as -V and pin 8 as +V shared for everything inside the package.

Can you just connect them in series? like +[]- --> +[]- ---> +[]- , from one negative to the positive on the next?
If the power amp rails are only +/- 30 volts or so, you can use for instance a 7815 +15v reg and a 7915 -15v reg to drop each of the power amp rails down to +/- 15v to feed the opamps. Run each of the opamp pin 8's to the 7815 reg, each of the pin 4's to the 7915 reg. Note!! These regs have different pinouts! Also they are probably a bit old hat nowadays, someone may suggest better.

One transformer to power the whole lot will certainly work well enough to get a good enough idea about what is going on with the whole cct.

Embarassed? When I was about 12 I was looking at a catalogue of digital IC's and I wondered whether a "Hex inverter" listed there was something that inverted hexes, whatever they were supposed to be...
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