My_Ref RevO

[ClaveFremen]

I've fixed both schematic and PCB...and I've found a tiny routing error on the positive regulator, fixed.

[AndrewT]

I still don't see it.

The amplifier PSU shows only two AC connections (AC1 & AC2) from the transformer.
For a dual bridge rectifier, the transformer must be a dual secondary and each secondary has two taps/ends. I expect to see AC1a, AC1b, AC2a, AC2b, i.e. 4 tapas/ends.
That is not shown.

VR2 is still wired differently from VR1.

OK, settle for inadequate smoothing caps after you have stated that the PCB size is more important to you than your realisation that other designers have increased the smoothing cap values

the My_Evo has 10000uF smothing caps for each pump.

[ClaveFremen]

Originally Posted by AndrewT

I still don't see it.

The amplifier PSU shows only two AC connections (AC1 & AC2) from the transformer.
For a dual bridge rectifier, the transformer must be a dual secondary and each secondary has two taps/ends. I expect to see AC1a, AC1b, AC2a, AC2b, i.e. 4 tapas/ends.
That is not shown.

Andrew, as I've already said they're there (AC1+PGND1 and AC2+PGND2)

I do agree that names are probably wrong (in fact I've changed them as you can see in the attached updated version) but they still are the four connection you're expecting...

BTW with a different arrangement I've managed to re-implement holes for bulk wire.

Originally Posted by AndrewT

VR2 is still wired differently from VR1.

Exactly, so they must be.

Please take a look on the schematic (there's also a PS detail) and point me to the error.

Originally Posted by AndrewT

OK, settle for inadequate smoothing caps after you have stated that the PCB size is more important to you than your realisation that other designers have increased the smoothing cap values

No, Andrew, in the Evolution there's space for four 10000uF per channel, 2 for pump #1 and 2 for pump #2.

If you have a single pump, like in the MyRef, there are only 2 big caps...



I can't really understand if you want to help or only criticize..

[AndrewT]

That's an improvement. You have removed ground references from the secondary connection points.
VR2 is different from VR1. You have said it need be different

Exactly, so they must be.

why?
Don't they supply the same voltage, i.e. 12Vdc?

It's possible but also the My_Evo has 10000uF smothing caps for each pump.

The PCB is already tight and full with 30mm caps, in this moment I can't imagine how to stretch in 35mm ones (and bigger value caps are mostly 35mm...)

Maybe I can't read, but I interpret your statement as: Two 10mF need two 35mm diameter footprints, but I only have 30mm diameter spaces available, so I'll just fit smaller value capacitors.

If two pumps need four 10mF, then why should one pump get two smaller capacitors? This does not make sense to me.

[ClaveFremen]

Originally Posted by AndrewT

That's an improvement. You have removed ground references from the secondary connection points.

That's only a different components arrangement and more clear naming, schematic is the same...

Originally Posted by AndrewT

VR2 is different from VR1. You have said it need be different why?
Don't they supply the same voltage, i.e. 12Vdc?

Yes but one is a positive regulator the other is negative...

Take a look at the attached comparison, schematic is identical.

Obvioulsy since TL431 (datasheet) it's not a simple zener it needs two additional resistors for voltage setting.

Maybe there's something wrong?

If so please tell me what is.

Originally Posted by AndrewT

Maybe I can't read, but I interpret your statement as: Two 10mF need two 35mm diameter footprints, but I only have 30mm diameter spaces available, so I'll just fit smaller value capacitors.

If two pumps need four 10mF, then why should one pump get two smaller capacitors? This does not make sense to me.

No, what I've said is that, as the RevC PCB, mine has space for two 30mm smoothing caps so 2x 10000uF 63V is the maximum (and suggested) value.

Bob was asking if there is need for caps bigger than 10000uF.

2 per 10000uF are plenty for the MyRef... and hundreds of kits, including yours, perfectly works with those caps.

[aymcheng]

R29 and R30 should be swapped to get correct voltage

[ClaveFremen]

Originally Posted by aymcheng

R29 and R30 should be swapped to get correct voltage

Yep!

Right, thanks Amycheng

Andrew, probably you were pointing the same error... just be a bit more clear next time, it was not wired differently, it was wrong , thanks

I've attached the fixed schematic and PCB.

BTW, adding an elco parallel to R27 and R29, according to this article should lower and linearize impedance, any opinion on it?

[soongsc]

Has anyone tried switching power on these?

[ClaveFremen]

Originally Posted by soongsc

Has anyone tried switching power on these?

Hi Soongsc,

not yet, I'm still in the design phase...

I've tried so far (on MyRef RevC):

- the TL431 PS (it works but I'm not sure it's better than zeners)
- different changes in the compensation scheme (all of them works)

I'm investigating some better (but simple, low component count) LM318 PS at the moment.

I've yet to try:

-the voltage limiter
-the PCB itself

Regarding the PCB I still need help on design and best practices, but so far no comments on it...

[soongsc]

I recall Mauro provided a good list on layout practices, as usual the devil is in the details. Not too long ago working on a different design, I discovered that any two components placed close together will interact with each other, due to the electromagnetic effect of the small amounts of current. So it's also a good practice to check the direction so that these sort of run perpendicular to each other.