OPA627 Pre with onboard regs

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VT67

VT67

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Joined 2004
As far as I can see it, that is a two layer board so all the holes will be plated through. Therefore it's not a problem on the elco's and connectors. The only thing I would change are +/- traces. Now they are starting from the big elco. I would make the trace between the elco and the filmcap wider and let the two traces going towards the op-amp start from the pad of the filmcap and not from the elco.
For the rest, nice idea Tobias.

Regards
 
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mzzj

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Joined 2005
Somehow i dont like this kind of looking "star ground" And those filmcaps are effectively connected with 2-3cm lead lenghts. My layout would look definetely different, alltough i dont know if better or worse in practice.

I would fiqure out "dirty" power ground connections and all sensitive analog connections and connect them at separate star grounds, and connecting these two with single track. Bit same idea as breaking up ground plane in HF desings
 
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tobias_svensk

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Joined 2004
Thanks!

I'm reinstalling my Windows right now and ahve just 16 colors on my screen so I can hardly even read text here :cool:

Hello GeWa, just a basic idea yet so tweaking it is :)
But were do you mean? :)
It goes like this: 1200uF->220nF->REG->220nF->220uF->100nF

And was it you GeWa that asked me some questions about 3D Eagle before? if you having trouble just ask :)
 
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mzzj

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Joined 2005
And also those local bypass caps right on both sides of IC, horribly long ground tracks and about half a hectare of area between them. Altough 627 is not fastest beast on this planet and your layout is probably stable, I just dont like it.

Place local decouple next to IC, combine capacitor gnd leads with shortest and thickest track possible. Star ground CAN be a good thing, but dont sacrifice everything else for that.
 
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tobias_svensk

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Joined 2004
Hello mzzj

Good, the thing I wanted to know was if this kind of grounding was bad or not. Probably I won't even try it I have another finished one.

But I had in mind to have the inputground and outputground connected togheter with a trace and then a trace back to the starground, but I just connected them very close to each other at one big elko.
 
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mzzj

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Joined 2005
tobias_svensk said:
Hello mzzj
But I had in mind to have the inputground and outputground connected togheter with a trace and then a trace back to the starground, but I just connected them very close to each other at one big elko.
Click to expand...
Yeah, I notice this in your layout and its a good idea to bring them together at very same point of your rather large star groung "point" At extremes even sharing that elko leg/PTH as a common path for dirty filtering cap spikes and your signal can be a bad thing, if you go to all the work doing "perfect" star grounding then you should bring your input ground trough the board by separate via, not share a piece of wire that carries nastiest current spikes and interferences in your whole board.
 
VT67

VT67

Member
Joined 2004
Hello GeWa, just a basic idea yet so tweaking it is. But were do you mean? It goes like this: 1200uF->220nF->REG->220nF->220uF->100nF
Click to expand...

Disregard my comment on the traces. I mixed up the GND traces with the +/- traces.:xeye: Sorry about that.

And was it you GeWa that asked me some questions about 3D Eagle before? if you having trouble just ask
Click to expand...

Yep, that was me. But for the moment I'm to busy with work to fiddle around with Eagle and Eagle 3D. I will give it another go as soon as I have a bit more time. I need all my concentration for work at the moment and I'm not getting any younger. As a matter of fact, today I'm yet another year older:drink:

Cheers
 
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