Linear power supply
#1
I just received a TeraDak U9 linear power supply to replace the iPad power supply I was using to power the Blitzortung blue board. It was a little costly, but it did cut down on the noise pretty good, as shown on the magenta E-field channel in the attached pictures. 
I'm not sure if it really makes a big difference in accuracy of the system, but I'm pleased with the results.


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#2
(2017-08-30, 18:24)JupiterJoe Wrote: I just received a TeraDak U9 linear power supply to replace the iPad power supply I was using to power the Blitzortung blue board. It was a little costly, but it did cut down on the noise pretty good, as shown on the magenta E-field channel in the attached pictures. 
I'm not sure if it really makes a big difference in accuracy of the system, but I'm pleased with the results.

Can you show how the voltage signal from the power supply looks like?
Menu "Blitzortung.org Controller" -> "Signals" tab -> "Signal Tools" -> "Sampling:" -> "Channel: V_in"
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#3
Here you go.
It seems lower on that than it does from the controller status page. I wonder why this is? Is this too low? Their website says output voltage is adjustable, but I'm not sure about that.


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#4
Thanks, quite nice graph Smile
This is mine - terrible Angry (Scale of 0.5V - just like you).
Different voltages: CPU, Input Voltage.


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#5
At least you aren't under power, but I don't know if over is good either... I wonder if it makes any difference?

I found that the USB voltage can't be adjusted on the unit I got, but there's another DC output that can be. I tested that one, and it's 5 volts on the nose. I just need to get an adapter for the plug that will connect to a USB plug. (Already have one on order) 

What kind of power supply are you using?


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#6
(2017-08-31, 01:23)JupiterJoe Wrote: At least you aren't under power, but I don't know if over is good either... I wonder if it makes any difference?

I found that the USB voltage can't be adjusted on the unit I got, but there's another DC output that can be. I tested that one, and it's 5 volts on the nose. I just need to get an adapter for the plug that will connect to a USB plug. (Already have one on order) 

What kind of power supply are you using?

This will handle all the required stuff....
https://www.powerstream.com/AC-1898.htm
Many of us use this little jewel... you just need to hardwire a mini-usb connector to it,
since it doesn't come with one...,. set it for 5 volts, tape down that selection switch, and rock on...
$15.25 plus shipping.... I've got a house full of 'em.
supplies plenty of current, regardless of the voltage you 'signal' page displays... works fine.

Overvoltage ain't good... down to about 4.25 should work, but I wouldn't run mine that low!!!! Not for long!
don't let it go over about 5.25....If I'm below about an indicated signals page voltage of 4.65-4.75 something is likely amiss... not enough current from wall wart, or at the margin, for example.  if you've got a good, current rated supply, it should regulate at source fine.
See the specs on that 1898.... the source input on my BLUE at 115V right now is showing 4.95 volts with DVM, signals page is indicating 4.55...   (i've a pre-release controller with piggy-back power supply mod board hung on... ).... My Red is on the button at 5.0 source, and 4.75 on signal page.
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#7
(2017-08-31, 01:23)JupiterJoe Wrote: What kind of power supply are you using?

The previous chart is from the power supply Samsung 5V, 2.0A (from the Samsung Galaxy S2 tablet).

Below are charts from another power supply: Samsung 5V, 1A (from Samsung Galaxy S4 mini smartphone).
The voltage often jumps as shown in Figure 2. Despite this, this new power supply seems better.


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#8
I have checked my power supply, and sometimes it also showes this jump in the voltage. Another one had a similar behaviour, so it seems to be a bug of all these switching power supplies!  Unfortunately, I threw away my nice linear 5V power supplies some time ago... Thought I would never again need them...


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#9
Any suggestion for low-noise power supplies which are for sale here in Europe (and which are affordable)?
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#10
Photo 
Are you sure the voltage jumps aren't just a feature of the supplies regulation and changes in load? Looking at my system there are longish periods of "noise" at about 50 mV peak to peak with section of jumps of about 20 mV P-P. the "jumps" may coincide with the detection of strikes, and thus the sending of data and flashing of several LEDs.

Both these images are the same supply, without inline filter:

[Image: attachment.php?aid=2674]

With inline filter:

[Image: attachment.php?aid=2675]

The controller objected to the unfiltered supply but is very happy on the filtered. Vertical resolution of 1 V/div.
Cheers
Dave.

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#11
(2017-09-11, 14:52)pasense Wrote: Any suggestion for low-noise power supplies which are for sale here in Europe (and which are affordable)?

Maybe apply a suitable, simple low pass LC filter?
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#12
(2017-09-11, 19:31)kriu Wrote:
(2017-09-11, 14:52)pasense Wrote: Any suggestion for low-noise power supplies which are for sale here in Europe (and which are affordable)?

Maybe apply a suitable, simple low pass LC filter?

That is all the inline filter above that effectively kills the noise from the supply. Still have the "spare" PCB if anyone would like it. Takes a couple of torids from Amazon/eBay with provision for two capacitors on the in and out side.
Cheers
Dave.

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#13
(2017-09-17, 19:05)allsorts Wrote:
(2017-09-11, 19:31)kriu Wrote:
(2017-09-11, 14:52)pasense Wrote: Any suggestion for low-noise power supplies which are for sale here in Europe (and which are affordable)?

Maybe apply a suitable, simple low pass LC filter?

That is all the inline filter above that effectively kills the noise from the supply. Still have the "spare" PCB if anyone would like it. Takes a couple of torids from Amazon/eBay with provision for two capacitors on the in and out side.

Could you show us a picture of it and where it fits, i.e. will it fit inside the case for Blue somewhere, or is it a separate "box?" Simple Circuit Diagram?
Or is it on the output of a PSU, Would it fit in the box with a small linear PSU. I am waiting for components to build a small linear PSU hopefully it won't
have too much noise at the frequencies of interest.

Brian.
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#14
Is such a filter like that could help reduce the noise?
Or similar by home made.


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#15
See this thread :-)
https://forum.blitzortung.org/showthread...1#pid12151

/Richo
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#16
[quote pid='15696' dateline='1505725678']
Could you show us a picture of it and where it fits, i.e. will it fit inside the case for Blue somewhere, or is it a separate "box?" Simple Circuit Diagram?
Or is it on the output of a PSU, Would it fit in the box with a small linear PSU. I am waiting for components to build a small linear PSU hopefully it won't
have too much noise at the frequencies of interest.
[/quote]

A half decent linear supply won't need a filter...

Have a look at this thread:

https://forum.blitzortung.org/showthread.php?tid=1911

There is a picture of my filter to the left of the naked PoE splitter. I think there are some more somewhere showing my installed controller, but I can't kick the forum search into finding that thread....
Cheers
Dave.

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