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All,
If you have not done a SMPS using a micro as the control element
its a venture into control theory and has unique dynamic.??
The control loop is running at 1MS, the switching rate PWM signal
is likely 10 times higher .
Add to that a transient, even if the processor was triggered by that
(interrupt) it?still takes a finite time to process and react.
There are many dynamic elements some in the analog realm and
other is the digital/coding realm.
Without the details aka code all of this is speculation.
That said then Hans sees a problem he solves it.
--
Allison
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Post online only, please no email.
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AIUI the pulse rate is of the order of
150 kpps.
The thing that's innovative about this
is that the switching rate is controlled by the MCU so the
switching noise is moved away from the frequency of interest.? Is
there such a thing as a switch mode controller which can have it's
frequency set by an external clock?? All I've found are some that
use resistors, not a clock.
Chris, G5CTH
On 31/07/2023 23:24, ajparent1/kb1gmx
wrote:
toggle quoted message
Show quoted text
All,
If you have not done a SMPS using a micro as the control element
its a venture into control theory and has unique dynamic.??
The control loop is running at 1MS, the switching rate PWM signal
is likely 10 times higher .
Add to that a transient, even if the processor was triggered by
that
(interrupt) it?still takes a finite time to process and react.
There are many dynamic elements some in the analog realm and
other is the digital/coding realm.
Without the details aka code all of this is speculation.
That said then Hans sees a problem he solves it.
--
Allison
------------------
Post online only, please no email.
|
Hi Chris
The switching frequency is 116,666 Hz (117kHz approx) but as you said, it can vary a bit either way. This is shown in the diagnostics screen in the terminal.
There IS such a thing as a switching controller having an external frequency input. During the design stages of QMX I did find these devices however I had concerns over the ongoing availability and the price. Post semiconductor shortage crisis the world still isn't back to normal. I also thought the discrete component design is interesting, educational and cool.?
AIUI the pulse rate is of the order of
150 kpps.
The thing that's innovative about this
is that the switching rate is controlled by the MCU so the
switching noise is moved away from the frequency of interest.? Is
there such a thing as a switch mode controller which can have it's
frequency set by an external clock?? All I've found are some that
use resistors, not a clock.
Chris, G5CTH
On 31/07/2023 23:24, ajparent1/kb1gmx
wrote:
All,
If you have not done a SMPS using a micro as the control element
its a venture into control theory and has unique dynamic.??
The control loop is running at 1MS, the switching rate PWM signal
is likely 10 times higher .
Add to that a transient, even if the processor was triggered by
that
(interrupt) it?still takes a finite time to process and react.
There are many dynamic elements some in the analog realm and
other is the digital/coding realm.
Without the details aka code all of this is speculation.
That said then Hans sees a problem he solves it.
--
Allison
------------------
Post online only, please no email.
|
On Mon, Jul 31, 2023 at 12:51 AM, <Ugglekatten@...> wrote:
There is a 1000 uF capacitor between the positive and negative power output. (Obviously not so good at filtering out spikes...)
Hi Gunnar, a 1000uF electrolytic capacitor seems to be definitely way too lazy to smoothen out those spikes. This is obviously not what they are made for. Try a smaller tantalum capacitor, anything less than 10uF and put a small ceramic capacitor (anything between 10 an 100pF) parallel to both,? This is at least what I would do: you might have a better idea and even think of an inductor happily dimensioned and placed in series with the rig, if the goal would be ironing those spikes flat! I have played with such a voltage supply switching idea following a qst idea (applied to a Rockmite) of buck-increasing the supply voltageup to 11..12V only during TX and feeding the rig during Rx with clean 7,4V coming directly from 2 LiPo cells while the buck-up-Converter is set to sleep. It never worked convincingly and the bottom line of this experiment was that a such quest should be implemented in the original design of the rig, and not as an after-market addendum. Yours friendly, Razvan DL2ARL
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Razvan, good idea, and I already put 150nF in parallell to the 1000uF when I saw the spikes
Gunnar / SM5EIE
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I would suggest collecting some more information on on the OP’s 2 switch mode power supplies as well to recreate or explore this issue. ?
Two low cost SMPSUs in a row may mean strange distortions of the supply waveform in between them and odd current flows at frequencies not seen in normal operation. ?
On the face of it a SMPSU should react quicker than a linear PSU with an ‘anti spike’ capacitor in the voltage monitoring circuit ?but both can enter unstable or oscillation and failure modes if the loop design allows it and some aspect of usage provokes it?
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On Tue, Aug 1, 2023 at 03:35 PM, DL2ARL wrote:
following a qst idea (applied to a Rockmite)
I was wrong, but now: I see! it was not a qst idea, but one from CQ Magazine: CQ March 2015 QRP Special Page 18: Behold Rockmitey, de ED Cobb K4YFR es Ray Kauffman AJ4YN. A memorable piece of reading. Sooo sorry that it has found as good as no resonance among the qrp comunity? :,-(
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On Thu, Aug 3, 2023 at 1:39?AM DL2ARL < dl2arl@...> wrote: On Tue, Aug 1, 2023 at 03:35 PM, DL2ARL wrote:
following a qst idea (applied to a Rockmite)
I was wrong, but now: I see!
it was not a qst idea, but one from CQ Magazine:
CQ March 2015
QRP Special
Page 18: Behold Rockmitey, de ED Cobb K4YFR es Ray Kauffman AJ4YN.
A memorable piece of reading. Sooo sorry that it has found as good as no resonance among the qrp comunity? :,-(
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Hans, thank you for all your hard work solving this difficult problem.? I do have one question though - after having been through all this effort, do you have any thoughts on building a QMX for 9 volts or 12 volts with regard to which is preferred from an internal buck converter standpoint?? Assembled?kits by default, are assembled for operation from a 12V supply.?The assembly manual leaves it up to the user.??My power supply situation is that I will be using my QMX primarily from home and can provide power for either one. Some builders will prefer 9V because it has slightly higher power output at the specified voltage. Others will prefer 12 volts because it is easier to drop the voltage at less external power dissipation from 13.8 volts.? Still others choose based on battery operation with their particular preferred battery configuration.? Any thoughts?? I am slowly and carefully progressing with my assembly.
Thanks,
Steve K1RF
------ Original Message ------
Date 8/3/2023 3:51:18 PM
Subject Re: [QRPLabs] #QMX I roasted my QMX, do not repeat my mistake
On Thu, Aug 3, 2023 at 1:39?AM DL2ARL < dl2arl@...> wrote: On Tue, Aug 1, 2023 at 03:35 PM, DL2ARL wrote:
following a qst idea (applied to a Rockmite)
I was wrong, but now: I see!
it was not a qst idea, but one from CQ Magazine:
CQ March 2015
QRP Special
Page 18: Behold Rockmitey, de ED Cobb K4YFR es Ray Kauffman AJ4YN.
A memorable piece of reading. Sooo sorry that it has found as good as no resonance among the qrp comunity? :,-(
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Thank you Hans for your effort and professionalism in investigating this problem!
A very interesting article, well worth reading! Now it is over midnight in Sweden, but I feel more excited than sleepy :-)
I feel reassured that with reasonable precaution from my side, my new QMX will not blow up.
I will definately not switch from 6 to 12V again, even if, in my case the killing ramp-up took 3 milliseconds
73 de SM5EIE / Gunnar
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I read both the short and long (to the end) of Hans’ QMX story.
I am only 80 and have been working around radios and electronics since I was around 12-14 but not the brightest guy on the block.?
As a purchasing agent, manufacturing manager , programmer and on and on……… I have never dealt with a company, let alone a single person, capable of designing, building, troubleshooting, reporting after testing, dealing with family and so very many other issues. To the degree that Hans does all this, It just blows my mind!!
Not only do I take my hat off to you, my head goes with it too !!?
I don’t even have a QMX yet.
John KK4ITX? ?Each mistake is a learning opportunity.?
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On Aug 3, 2023, at 6:28 PM, Ugglekatten@... wrote:
?Thank you Hans for your effort and professionalism in investigating this problem!
A very interesting article, well worth reading! Now it is over midnight in Sweden, but I feel more excited than sleepy :-)
I feel reassured that with reasonable precaution from my side, my new QMX will not blow up.
I will definately not switch from 6 to 12V again, even if, in my case the killing ramp-up took 3 milliseconds
73 de SM5EIE / Gunnar
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I do have one question though - after having been through all this effort, do you have any thoughts on building a QMX for 9 volts or 12 volts with regard to which is preferred from an internal buck converter standpoint??
Normally buck converters are more efficient with a smaller voltage drop. Therefore from the buck converter standpoint, 9V is probably marginally preferable. But really it doesn't make a lot of difference to it, it's fine either way.? ? Assembled?kits by default, are assembled for operation from a 12V supply.?The assembly manual leaves it up to the user.??
Yes, but for assembled radios it's also up to the user; all I'm saying is that if you don't specifically ask, you get 12V. If you make a comment or request for 9V assembly, that's fine too...?
73 Hans G0UPL
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DL2ARL
Bruce Akhurst
KK4ITX John