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  • Users: MacGyver15147
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  1. MacGyver15147

    electrolytic capacitors shelf life

    So as a licensed A&P mechanic I am trained to have at least 3 reference that can verify that what I am doing is correct and confirmed by all the sources before ever touching an aircraft to a F.A.A inspector at any time. IRstuff as you list your profession as "aerospace" do you read and follow...
  2. MacGyver15147

    Which DMM can you recommend?

    So originally the question was cost vs. performance. As stated accuracy in not important. In your case like mine 99% of the time we just need to verify 480v is not present when pulling out a fuse or looking for a dead leg. For that I have been using the harbor freight DMM which is free if you...
  3. MacGyver15147

    electrolytic capacitors shelf life

    Read the posts IRstuff. That's At least 3 conflicting sources. Conflicting sources = Nothing solid
  4. MacGyver15147

    equipment damage due to voltage supply

    Always use a surge protector strip for electronics. Sounds like either a power surge or brown out condition which would be like repeatedly unplugging and plugging in a device several times a second causing loss of steady 60 cycle power. Don't think there is any kind of protector for home use...
  5. MacGyver15147

    Best metal for corrosive environments in the oil and gas sector

    Aluminum Bronze seems a good choice for malleable applications and for higher strength an alloy of Silicon Bronze could be used for fasteners. Keep in mind if any kind of flammable environment is involved bronze is used for making non-sparking tools.
  6. MacGyver15147

    electrolytic capacitors shelf life

    I just hate using my better judgment with nothing solid to back it up. From what I have researched and compiled would be to use a power source at 1/4 the cap rating with a 1K ohm resistor on the positive side for 10 min. then up the voltage to 50% the caps rating for 20 min.
  7. MacGyver15147

    electrolytic capacitors shelf life

    Again back to conflicting info. one source says it best to use 1/2 rated voltage the other says use full voltage rating. Other sources later on say never use full voltage which makes sense that if you push something straight to the rated breaking point it may break. Other sources are saying...
  8. MacGyver15147

    electrolytic capacitors shelf life

    Done all the Google searches before posting the question. Come up with nothing relevant. Yes just installing an old cap and turning on at full power will usually just work fine and they fix themselves. Electrolytic capacitors have when new usually a 20% tolerance. As sitting around too long they...
  9. MacGyver15147

    Pressure Test Area Construction

    The layered panel should be much stronger than a single 3mm. This is how bulletproof armor and windows work. The only down side is once a layer is damaged it needs replaced as they must work together. For example a bullet proof windshield can stop a bullet once but I wouldn't want to be around...
  10. MacGyver15147

    Best metal for corrosive environments in the oil and gas sector

    I would consider using a marine grade bronze. Here is a list of bronze alloys and their properties. http://www.onlinemetals.com/bronzeguide.cfm
  11. MacGyver15147

    LiPo batteries

    So basically when you add two 900mah batteries in parallel you will get my target of 1800. This doesn't seem too out of the question for aaa size. I do have a spare camcorder battery rated 2200mah but is just slightly too large to fit inside the case. I was thinking if nothing else I would make...
  12. MacGyver15147

    electrolytic capacitors shelf life

    So trying to get back on the subject. Has anyone actually "reconditioned? caps before? Does anyone know of a mathematical equation to do this properly without guesswork? Is there a chart somewhere online which lists voltages, correct current limiting for the cap size, and the time required to...
  13. MacGyver15147

    electrolytic capacitors shelf life

    This is just an example of cap conditioning I have found. Note that this is for very large caps and not very detailed. Useful for the application yes but not a good "rule of thumb" for all caps like this. https://www.youtube.com/watch?v=HuALonM_1X4
  14. MacGyver15147

    electrolytic capacitors shelf life

    VE1BLL seems just as confused as me with no facts or proven answers. My out of spec description can mean anywhere from 5% to 35% in my case on the caps I have tested. Current limiting and volt rating seems to be key factors here with my research. Yes buying a brand new name brand replacement...
  15. MacGyver15147

    Single phase switching capacitor start?

    Yes I will be using a VFD that has a single phase 220v input and has a 3 phase 230v out. If that is what you meant to say?
  16. MacGyver15147

    electrolytic capacitors shelf life

    By the way, "Love your user name" LOL
  17. MacGyver15147

    electrolytic capacitors shelf life

    No they are all brand new name brand caps unsoldered with untrimmed legs. Without exercise caps loos their charge i.e. "charge capacity" Just like old NiCad batteries they develop a "memory" to the discharged state. Not dried up just in need of something like a deep cycle for NiCad batteries to...
  18. MacGyver15147

    LiPo batteries

    So I was looking at these http://www.ebay.com/itm/4PCS-TrustFire-AAA-10440-600mAh-3-7V-PCB-Protected-Rechargeable-Battery-Charger-/291135585726?pt=US_Rechargeable_Batteries&hash=item43c9087dbe They seem to be close to what I want however 2 in parallel only comes up to 1200mah which is a bit...
  19. MacGyver15147

    Single phase switching capacitor start?

    I have also work with many 3 phase motors up to 250hp in hammer mills that would start to leak smoke after 2 failed starts in 15 minuets during ramp up time pulling around 1500 amps. Unskilled operators would make one go kaboom around once a month. Smaller motors can handle far more abuse due...
  20. MacGyver15147

    electrolytic capacitors shelf life

    I have found that electrolytic capacitors only have a shelf life around a year. By not being used they degrade and read out of spec. I purchased a large assortment of caps and found many are reading low when tested. I have herd of reconditioning but finding conflicting info on how best to do...

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