Re: QMX - smoke - another C107/Q108 failure
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Hello Razvan
If you use linear 3.3V and 5V power supplies it will work fine, and there is no harm in the 5V coming alive before 3.3V. In order to make the processor complete the boot process you will need to arrange the 3.3V and 5V ADC measurements to both be above 1.65 and 2.5V respectively; the easiest way to do this is simply connect them to the 3.3V supply rail.?
On Fri, Aug 25, 2023 at 12:38?AM DL2ARL < dl2arl@...> wrote: On Thu, Aug 24, 2023 at 01:46 AM, Rick Crowther wrote:
I meant only to rig up temporary linear supplies on my bench
hello Rick, Hello Hans,
this is exactly what I was aiming for myself: a temporary replacement of the smps boards until all other smoke tests have been succesfully passed.
Hans: really no offence intended! I am of an older school and do not trust these new-age gadgets piloted by software, not because of paranoia, but because of the fact that they do not belong to my trusted analog world. I find the ideas standing behind the SMPS concept of the QMX most refreshing and innovative: this is the main reason I am glad of having purchased a QMX, without having been in need of yet another qrp toy.
But now.. I am sort of discouraged by my own courage and would like to go one step behind into those quiet linear waters I am used to. Not for good, but at least for the first current intake of the fine rig. Afterwards, having thanks to Chris a test checklist for the SMPS boards outside the rig, without danger of damaging the main professor, I would maybe gain some courage and "replace the linear replacement" with it's new age microprofessor controlled switching PS.
This is what I meant. You might help by telling me if this is doable or if I am to expect some latch-up phenomena during power-up due to the fact that the 5V rail would come alive before the 3,3V would do. But latch-ups are not harmfull, so if you do not have an answer to this question, just forget it: I will find it out by myself.
Yours friendly, Razvan dl2arl?
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