[Arm-netbook] Oscilloscope or bust?

[Christopher Havel]

Sounds like you're taking your plunge at the deep end of the pool, and
you're getting a bit lost along the way because you're in over your head.

Get this book. Read it. Study it. Build things. (Don't trust eBay for
parts! I know this from experience.) You will LEARN.

https://www.amazon.com/dp/0945053282

Alternatively, if you dig around, you may be able to find a PDF copy of
"MAKE: Electronics" online. That would also be a good book to start with.

First learn to swim. Then learn to dive. Then you can truly get out of the
shallows...

On Sun, Sep 23, 2018 at 3:54 PM David Niklas <doark at mail.com> wrote:

> On Sun, 9 Sep 2018 23:25:42 -0400
> David Niklas <doark at mail.com> wrote:
> > Hi,
> > I need help here. I was designing the power supply of my laptop and I
> > noticed that some power bucks and step up/down converters (Which both
> > seem to do the same thing. Please tell me otherwise.), produced a more
> > stable power supply than others. In order to find out if they are truly
> > suitable for suppling power to sensitive electronics I've heard that I
> > need an oscilloscope.
> > I currently own:
> >
> > 1. #222634543946
> > "DC-DC 10/12/15/20A 150/250/300/400/1200W Step up Step
> > down Buck Boost Converter"
> >
> > 2. #152710861245
> > "2A DC Boost Step-up Adjustable Converter Module 3v-24v to 3.3v 5v 6v
> > 9v 12v 24v"
> >
> > After learning that some guy with an oscilloscope reviewed these, I'm
> > planning to get: #122923215542
> > "6 Pack MP1584EN ultra Small DC-DC 3A power Step-Down
> > Adjustable Module Buck M2H3 6 Pack MP1584EN ultra Small DC-DC 3A power
> > Step-Down Adjustable Module Buck"
> >
> > I've seen many oscilloscopes online on crowd funding campaigns. I've
> > never been certain of which to get, if any. The real professional ones
> > are out of my budget range of about $100. *I'll pay more if I must*,
> > but I already did not anticipate the need to actually evaluate what
> > should be solid products.
> > I probably should find a solid adjustable DC power supply to test these
> > with vs. an old laptop power pack or some batteries.
> > What I need some of these things to do is to take a dynamically variable
> > voltage as input (Li-Ion batteries in series), and produce a constant
> > voltage as output. Others I need to just convert to the correct voltage
> > from the old laptop power pack.
> >
> > Thanks!
> > David
>
> Alternatively, does anyone know a good place to ask?
>
> I searched a lot online and found a forum www.electro-tech-online.com
> which I signed up to and was rejected. It was a very weird sign up
> process. You're supposed to input your name but the form will only take
> one character (and allows white space as that one!) You also have to tell
> what education level you're at (I choose student), and what your
> expertise is, which being a student was none, but they did not have that
> choice and the others were things like "PCB layout engineer," so I
> selected everything.
> After being rejected I wrote to the admin asking the reason and have yet
> to get a response after about a week...
> In other news, I found a couple of guys on youtube who did a review of
> the 300W buck converter I own and it seems to be a good model with a
> 168mhz switching freq and 218ma voltage variation independent of load, but
> I must confess that I have not done any work with computer circuits until
> now so they might have stricter requirements than I think.
> So, I think I'll add a 3.3uf capacitor onto the leads and call it quits
> from there. 3.3uf should be able to reach saturation at 168mhz unless my
> calculations of the time constants are incorrect. Feel free to check me
> on that, I did use a calculator this time (I learned via pencil and
> paper and I still have my notes!)
>
> Still, I think I could use a good place to ask these questions on because
> although this list is called "arm netbook" it seems that a lot of
> questions I post on the subject go unanswered, but that might just be my
> perception :)
>
> Status update: other than the above, I'm still trying to find genuine
> Li-Ion batteries (both my stock of Li-Ion and my Ni-Mh batteries are
> duds. I did replace the Ni-Mh ones), and I managed to fry a pair of my
> tester leads (turns out that the tester is rated for 10A and the leads
> for 8A? So I'm building an open source set of leads. :) They "mind
> melded" to each other when I decided to test if my 300W buck converter
> would work.
> Another annoying thing is that it turns out that electrolytic capacitors
> are being faked in addition to batteries. I never needed a capacitor
> tester before because the ones that were not bulging were marked and the
> ones that are bulging are not safe. So I am getting a little TC1
> multi-function tester that was reviewed here:
>
> https://lygte-info.dk/review/ComponentTester%20Multifunction%20Tester%20T1%20UK.html
> The gentlemen also reviewed a bunch of batteries, but most of them are no
> longer available or are very expensive.
>
>
> Thanks!
>
> _______________________________________________
> arm-netbook mailing list arm-netbook at lists.phcomp.co.uk
> http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
> Send large attachments to arm-netbook at files.phcomp.co.uk