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 41 
 on: January 12, 2019, 02:09:01 02:09 
Started by Manuel - Last post by Manuel
Thank you to you all first of all !

Power lead length is 2000mm, but same issue is present with a length of 1000mm.

The same issue is present using 4.7uF ceramic capacitor.

Personally I think it is missing a proper output filtering from the switching power supply.

So, almost all your writings are good, to be honest what I underline is the following:

- if you use components suitable to work up to 18V do not expect that nothing can happen connecting a 12V switching power supply to them...

I think that the cheapest solution is to use different components in general, and remember: end users are allowed to use often their own power supplies, so you can not control how good are Vout filtering from those.

Anyhow, there are also other considerations that can be done: does a spike of 2us up to 20.8V will destroy a component that has 18V as absolute maximum rating ?

Thank you so Much !

take care,
Xo.

 42 
 on: January 12, 2019, 01:13:27 01:13 
Started by Manuel - Last post by Signal
There is nothing wrong with control loop. As pickit2 said this transient definitely caused by inductance. Just normal transient of passive circuit you can look at thanks to modern capturing oscilloscope.

Here is the model with similar behavior. Note how capacitance influences on overshoot.


 43 
 on: January 11, 2019, 04:29:31 16:29 
Started by motox - Last post by motox
Great solution, my compliments.
Do you think that a small diameter of the resistor leads can help to fit the metal parts inside the holes in the plastic top?
Thanks.
The ideal is to use neither too thin nor too thick.
I used what I had at the moment, a mix of thicker leads from another components and some from resistors (the thin ones).

 44 
 on: January 11, 2019, 04:18:15 16:18 
Started by motox - Last post by PICker
Great solution, my compliments.
Do you think that a small diameter of the resistor leads can help to fit the metal parts inside the holes in the plastic top?

 45 
 on: January 11, 2019, 04:00:42 16:00 
Started by Manuel - Last post by optikon
Also, the tantalum cap might not seem like too large of a value but it might also be contributing to a startup surge.

What is its voltage rating? Generally, tantalums should have some impedance upstream of them to avoid possibly failing short due to an inherent dV/dt kind of limit.

Significant voltage de-rating and a little bit of impedance is often the cure *if this is your issue*

You can try easy experiment, try adding ~ 0.5 Ohms in series with your cable and see it helps the start up issue. If you see the issue improve, its not a good solution but it can indicate thats the problem.

Alternatively, change the tantalum with an aluminum electrolytic of similar value. It will have a higher ESR.




 46 
 on: January 11, 2019, 02:53:51 14:53 
Started by motox - Last post by motox
I want to share a simple hint on how to reassemble a ZIF socket.
I printed a 3D enclosure for my cheap component tester, which I downloaded the STL file from the internet. Everything was OK except I could not fit the board, because of the ZIF socket handle. Therefore, the only solution was to disassemble the ZIF socket to remove the top part and the handle. Now the board fitted perfectly into the enclosure. Nice (see Fig 1).
The problem was, how to reassemble the ZIF socket?...
This is not a simple task. A search on the internet revealed only a YouTube video where the guy removes all the pins. This was not a solution because the socket is soldered to the PCB.
So I made the adapter shown in the Fig 2 with some resistor leads.

The procedure is the following (See Fig 3 the arrows represent the movement direction):
1 - Insert the top part with the adapter in.  All leads must be in the right place between the socket pins.
2 - Slide the top part of the ZIF socket until it is aligned with the bottom part.
3 - Turn down the handle.
4 - Insert the top part in place (now it shall be easy), remove the adapter and tighten the screws.

Problem solved  Cheesy

 47 
 on: January 11, 2019, 12:07:49 12:07 
Started by checooh - Last post by checooh
CountryRussia
NoteI'm an embedded firmware developer and electronics engineer, working with control and connectivity projects for industrial applications. Mostly I apply because here I have found the J-Link software, which I want to download.

 48 
 on: January 11, 2019, 11:01:54 11:01 
Started by Manuel - Last post by Mr. Spock
Is this an off-the-shelf power supply or your own design? The oscillating recovery can also be due to a bad control loop with insufficient phase margin. Do a load step with a pure resistive load and see if the recovery is any better.

I agree

 49 
 on: January 11, 2019, 09:44:21 09:44 
Started by Manuel - Last post by PM3295
Is this an off-the-shelf power supply or your own design? The oscillating recovery can also be due to a bad control loop with insufficient phase margin. Do a load step with a pure resistive load and see if the recovery is any better.

 50 
 on: January 11, 2019, 09:14:56 09:14 
Started by Manuel - Last post by pickit2
Do you have long power lead? sounds like a problem caused by lead inductance.
screen shows power fed into a short, then a fast recover, so over shooting.
you get this effect when powering up loudspeakers term used to correct it is called Slow Start up.

I seen such a problem solved with another capacitor and Diode.


Edit: change the tantalium as they have a Low ESR, you need a higher ESR.

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