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DIY laptop powerbank project

  • Ignatus Thursday, March 9, 2017 7:19 PM Reply

    Hi Sheepish.

    2.9V cutoff is good?  -Alright then , I was a bit worried that it might be too low.

    Thanks, for looking at the glorious messy switching thing I've built. -It works, but not reliably.

    - Was good fun for a first trial.

    It's just like the Youtube electronic master explains - There is no way to manually disconnect the trigger fast enough...

    Thanks for the video link! I've watched so many, but didn't come across this one and I've just seen that he also made a video titled:

    How NOT To Blow Up Your Oscilloscope!   -That is EXACTLY what I needed :)

    At first, after the glorious relay monster,  I thought about building a Sound Activated Latching Relay Switch.

    -That way the relay is decoupled from the Lipo charger. One could just put
    the mic really close to the buzzer and set the sensitivity very low.

    I started to look at Clap on/Clap Off devices (" As seen on TV") to
    harvest one of those for my project, but didn't seem to look like a good option because they are all built for AC circuits.

    Then I thought about implementing with some modifications this one:


    I then found another one:


    Not sure yet which one of the solutions I'll build. The last one and your Youtube solution look like a good fit. I think whatever parts I get my hands on first will be a deceiding factor.

    I guess it's about time that I get a breadboard along with some general prototyping PCBs and start hoarding electronic components in tiny plastic drawers like all serius geeks ;)

    Edit: Typos

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    post edited by Ignatus on 3/9/2017 at 8:33 PM
  • sheepish Top 10 Forum Poster Friday, March 10, 2017 5:41 AM Reply

    How NOT To Blow Up Your Oscilloscope!   -That is EXACTLY what I needed :)

    I hope it was in time.

    Remembering 30 years.
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  • Ignatus Saturday, April 22, 2017 4:21 PM Reply

    Hi everyone, sorry for not having posted any project updates. - I got
    swamped with work and could not dedicate more time till yesterday.

    Hi Sheepish,

    Yup, that link came just in time, but I blew up a large capacitor today :(

    Have plenty of parts now laying around and my office room transformed into a Gyro Gearloose  lab... looking at the chaos... I thought that it is about time to get this done.

    So, I finally put the rotary-switch based potentiometer together, soldered the old pot off the buck/booster's pcb, soldered the new DIY Poti on and gave it a test run with just 5 resistors (instead of 9) between 10K-80KOhm. Checking output voltage per step to try to determine the right resistor values to have 1VDC increments from 12V onwards...

    Started to turn the knob, measured DC output values for each step and then went one step too far... and POP!!! -Yep, now I know what a capacitor looks like from the inside.


    I have a differnt spare buck/booster board laying around and might use that. However, after the capacitor blew up, the board didn't show any other signs of further obvious damage, no magic smoke etc. .. and  all LEDs still working

    I may just try to replace the blown cap if I can find out the right value and find a replacement in my electronic junk box.

    Happy belated Easter wishes to everyone!

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  • sheepish Top 10 Forum Poster Saturday, April 22, 2017 7:40 PM Reply

    Very interesting. Thanks for the photo.

    Remembering 30 years.
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  • gasbag11 Top 10 Forum Poster Saturday, April 22, 2017 10:59 PM Reply

    Which one blew up?

    Heheh... even I'm not that stupid. Just wanted to return your belated Easter greeting.  

    NO! I don't know why DX screwed up the site so badly.
    Ask them.
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  • Ignatus Sunday, April 23, 2017 1:00 AM Reply

    Hi Sheepish,

    Yes, I'm almost proud of that photo and the experience was literally eye-watering.

    Note to self:  Maybe wear some eye-protection next time.

    - I guess it wouldn't have hurt (that much) to read just a little about Ohm's law before experimenting.

    Hi Gasbag, Happy.... "Easter-Saturday"  

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  • Ignatus Tuesday, April 25, 2017 9:36 PM Reply

    Could not find a capacitor of similar values in my junk box... cracked open a few old power supplies without luck.

    Then I found a pack of 10 capcitors online for $3 and they got delivered within 48 hours! Desoldered the exploded one , plugged in a fresh one and also changed the potentiometer back to a more regular 100K one.

    For some reason the new cap is a bit shorter than the original one, but so far it seems this buck-booster board is functioning again without any issues! Hurray


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  • desolder Top 10 Forum Poster Wednesday, April 26, 2017 3:12 AM Reply

    HAHAHA that's awesome. We used to blow up capacitors in university as pranks. Plug in the capacitor to the power supply in reverse, then quickly walk away. BOOM

    Ignatus, did you replace the capacitor with a low- ESR type. Standard capacitors may have too much ESR and overheat.

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • Ignatus Thursday, April 27, 2017 8:22 PM Reply

    Hi Desolder and everybody,

    I don't have an ESR meter at hand. Also, shortly after posting last time, I realized that my bag of capacitors contained two different versions. Specs were the same, but the form-factor was slightly different.

    I then went ahead and changed the previously replaced capacitor with another one, which looks form-factor wise almost excatly like the original blown up one. 

    I couldn't find a datasheet online and it doesn't have any low ESR marking. The one that I've put in now is  called "IMAGINE" and rated for +105C. I hope it survives for some time. - Yeah, I know... sounds like a super duper brand ;)

    Panasonic, Nichicon, United Chemicon or Rubycon were just not available for quick delivery, otherwise I would have gone with any of those.

    As a matter of fact all other capacitors on this pcb seem to be non low-ESR, except for one. 

    All of them are branded as CHENXING / VENT. 
 - Sounds like a magic, smoke venting brand :(

    There is only one capacitor, by the same brand, on this pcb that has been marked as "lowESR".


    Considering the manufacturer skimped out on decent capacitors to save a few cents, $25 for this board seems overpriced.  I'll choose another one next time. I've seen one with a display panel and digital based controller to adjust voltage settings with just a few button clicks.

    However, I highly doubt that any other manufacturer of these type of boards uses high quality components. The only solution would be to desolder everything and replace everything with some reliable branded parts, basically just using the plain pcb ...which most probably is also of low quality.

    Anyhow, life continues and the project too. I've started the box/woodwork today and placement of components. So far, some switches, voltmeter and Quickcharge 2.0 adapter have been fitted.


    To be continued...

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  • desolder Top 10 Forum Poster Friday, April 28, 2017 12:24 AM Reply

    At least they put a low ESR cap on the input, where it is needed the most. You'll probably be OK with a normal cap on the output. But monitor the temp of the cap with a test load attached and if you feel the top of the cap getting really hot, then you'll want to replace it with a low ESR type. sku.127866 should be suitable. The're supposed to be low esr. Datasheet here:


    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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