Voltage regulation circuit 12V to 5V in 5A range

[Demon]

That's what I said in the second part about getting more than 2A out.

You can't get 5A out if the adapter can only supply 2A

The 2A wall adapter was a quick fix to be able to continue testing.

The 9V 2A is holding up for now.

[Demon]

Received the LM1084-ADJ, still waiting on the recommended caps (to properly test ripples), but it's already running nicely with what I have on hand.

Also got a thermal imager to help identify hotspots. Looks like I fried 2 PICs with those 12V and 7V bursts (lesson learned).

LM1084-5V on right, supplies PICs, ICs and LCDs, essentially everything that is "always ON", with a slight tweak on ADJ pin to get it slightly above 5V to compensate for voltage drop.

LM1084-ADJ on left, supplies LED strips, cooling fans (to be determined) and anything else that doesn't care about ripples.

(HIKmicro E02)



No thermal compound yet, this was a temporary setup to help prevent forest fires.



I'm sure there's better ways to skin a cat, but this was the simplest technique I could come up with. It remains to be seen if the ripples are "manageable" for the ADC on the PIC circuit.

[Demon]

Wasted so much time trying to figure out why I STILL had a lot of ripples with the LM1084.

I checked directly on the wall adapter:



GIGO; can't expect the LM1084 to do miracles with that.


So I pulled out a 12V-5A Fqcmogu AL-1250 adapter (no idea what it's for):



Definite improvement.


This is the LM1084-5V running at 5.0V (LED strips and whatnot):




This is the LM1084-ADJ running at 5.2V (PIC, LCDs and other ICs), note that is had less ripples as stated in the specs:

[amgen]

if you didn't already........ put your probe lead on 'ground/negative' at a distance from the negative/ground probe connection..... and probe to various ground/neg locations. Sometimes noise is 'introduced' into circuits from other sources called common mode noise.....
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Key Takeaways

Noise appears in two forms in an electrical interconnect: as differential mode and common mode noise.
Differential mode noise is measured between two sections of an interconnect with equal and opposite polarity, while common mode noise applies to interconnects with the same phase and polarity.
Both forms of noise are induced in an interconnect via Faraday’s law from external radiation.

[Demon]

if you didn't already........ put your probe lead on 'ground/negative' at a distance from the negative/ground probe connection..... and probe to various ground/neg locations. Sometimes noise is 'introduced' into circuits from other sources called common mode noise.....
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Nope, haven't done that. Good idea.

I'm also redoing my prototype board to have a somewhat "star pattern" for VDD and VSS. Right now the 2 rails run all over the place.

Right now I'm just basking in the glory of having found the root cause of most of that noise on the lines, and started looking for a source of affordable "good" 9V 5A power adapters.

[amgen]

Right now I'm just basking in the glory of having found the root cause of most of that noise on the lines, and started looking for a source of affordable "good" 9V 5A power adapters.

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not trying to 'rain on your parade'..... it is possible that isn't where your noise is coming from...... if you haven't already, put a 10 or 100 microfarad electrolytical and a couple of .1 or .01 microfarad caps at the output of the power supply..... and I didn't look to see but you would want to put the same capacitor duo on each separate circuit board..... that SHOULD squash the noise. Plus..... a bunch of interconnected grounds running here and there are often culprits for noise. And keep in mind that often serious engineers and engineering is involved with noise and interference

[Ioannis]

Also breadboards are the worse for low noise circuits!

Ioannis