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Are you really fine with IC voltage regulators ?
Are you really fine with IC voltage regulators ?
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Old Today, 10:10 AM   #271
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by dreamth View Post
I kinda have a feeling that actually you don't like this topic's existence and you purposely divert it to offtopic...I caught you and a few other friends of yours doing it for a few times and i think it's not fair what you do using your name to drive discussions away.I remember you blaming me of being a politician once...Who's really doing the politics here?
Apologies - not by intention. Back to topic.

Jan
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Old Today, 11:01 AM   #272
jean-paul is offline jean-paul  Netherlands
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Quote:
Originally Posted by dreamth View Post
I kinda have a feeling that actually you don't like this topic's existence and you purposely divert it to offtopic...I caught you and a few other friends of yours doing it for a few times and i think it's not fair what you do using your name to drive discussions away.I remember you blaming me of being a politician once...Who's really doing the politics here?
Sorry but several people point to correct use of the writing of units. It is you that keeps writing standardised stuff not according easy international rules (Romania is also member of ISO). It makes making mistakes way easier if you don't follow simple electrical unit names. Many tech people get annoyed as they do follow these rules with a good purpose (also for you that is). If you want assistance then write stuff as intended.

Now you start being personal with "I caught you and a few of your friends". Before you know it race, color, religion etc. are involved.

Quote:
Originally Posted by jan.didden View Post
I think we may expect posters to write as clear as possible, just a matter of respect to the reader. Proper capitalisation and interpunction help a lot for easy reading and understanding.
Correct.
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Last edited by jean-paul; Today at 11:08 AM.
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Old Today, 11:15 AM   #273
dreamth is offline dreamth  Romania
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I'm not a woman...i don't expect to be challenged with flowers...Maybe i;m wrong about that capital Hertz problem...i honestly don't care if you ask me...

Last edited by dreamth; Today at 11:22 AM.
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Old Today, 08:44 PM   #274
martin clark is offline martin clark  Europe
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Originally Posted by Bonsai View Post
A 7815 can be used with a split winding transformer to provide both + and - regulated outputs and features wide band output Johnson noise of around 150uV RMS. If you use local filtering (22 Ohm and 100uF for example) around the opamps, the HF noise RTI of the opamp input is very very low - on a good opamp it will be pico Volts.

That leaves the LF noise. But there the opamp PSRR is very high, so you are still left with negligible noise RTI.
.
I've a lot of time for this.
I've just picked up a mint, later Quad FM4 tuner (an obvious gap in my accumulation of 'nice fm tuners')

Anyway, after a good look at the schematic, a look inside it and a poke with the 'scope - anything on regulated rails comes off one 7812.aha... I thought. Except, of course: Quad.

The input ripple to the 7812 is under 70mV and totally clean, thanks in part to rectifier choice, mains input snubber matched to transformer, and a useful amount of secondary winding resistance for a good dab of RC by design. The 7812 output ripple & noise, well under 100uV.

Then all the RF ICs it feeds have local, discrete HF LC decoupling (Thank you, PJW); the one LF IC (the TCA4500 stereo decoder) uses RC very much along the lines you suggest; look there with an LF opamp preamp for scope probe - its well into into the 'neurotics-only' category on the supply pin - on a part with >55dB PSRR.

Points to be gained by meddling with the factory-standard: nil. And that is a good thing.


(having put my neuroses back in the box - can confirm it sounds excellent, and shall do for many years yet.)

Last edited by martin clark; Today at 08:52 PM.
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Old Today, 09:28 PM   #275
jean-paul is offline jean-paul  Netherlands
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Quote:
Originally Posted by martin clark View Post
Points to be gained by meddling with the factory-standard: nil. And that is a good thing.
Well, that can only be proven when a low noise replacement for the 7812 is tried and measured. It won't have a detrimental effect anyway.

Quad FM4 is a nice tuner, too bad FM will be shut down here. Sold all my tuners as now DAB+ is the standard...
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Last edited by jean-paul; Today at 09:33 PM.
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