i want back in! (to electronics that is)

Discussion in 'General Electronics Chat' started by bill l, Oct 13, 2009.

  1. bill l

    Thread Starter Member

    Oct 11, 2009
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    0
    so i am new here and thought i'd tell my story, so here goes.......

    i got into electronics back in middle school, around '85, and have pretty much been into it since.

    i joined the navy and spent 7 years as a data systems tech, where most of my technical experience came from working mainly on digital equipment, with some occasional analog problems to work on. after the navy, i worked in a shop that dealt with military electronics and spent a year or so working on more analog stuff than digital. from then, it's been more rf related, but not so much component level stuff.

    what i am finding now, is that i want to get back into the analog side of things. i have been lately taking in vintage stereo equipment, i.e. marantz, pioneer, etc, from the '70's and bringing it back to working condition. in addition, i have picked up mid '80 to '90's car audio amplifiers and working on those.

    where it gets to be somewhat sad for me, is that i don't seem to remember half of what i used to think i know......(you read that correctly). *eta>>>>it seems that i can't remember a lot of the math and formulas.

    i can still read schematics and in most cases, with service manuals, i can still pretty much jump in and get the fault repaired. where the problem seems to lie, is for example:

    i have an audio amp that the preamp board is toasted. being a hybrid ceramic board containing all surface mount, it is not feasible to repair as traces were destroyed also. i want to simply bypass the preamp board and specifically use this amp with inputs coming directly from a preamp/equalizer with outputs at 0 to 2.5 volts.

    in this case, i find myself questioning how much i really know and how much i have seem to forgotten, and can this even be done, and i realize i still need the preamp section of the amplifier for the 0 to +/- vcc swing to appropriately drive the output stage.....

    anyways,

    so it's back to the basics of op-amps i go and i do the math, (which i have always sucked at) and pretty much am satisfied that i can build a new preamp board with good results.

    moving forward......

    i fortunately have the net, a decent rack of test equipment to include:

    tek type 422 scope
    tek 2246a scope
    fluke 8600a meter
    fluke 8012a meter
    a couple handheld dmm's
    some analog meters
    and various other items......

    so that is pretty much where i stand right now, an old newb to electronics.....

    if you made it this far without falling asleep, i commend you!

    thanks for reading and hope to be able to contribute to this site,

    bill
     
    Last edited: Oct 13, 2009
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Bill,
    Welcome to AAC, and thanks for your Service.

    Did you go through the Navy NEETS course? I went through a predecessor course at NAS Memphis back in the 70's. You can download the material in .pdf format for free from this site:
    http://www.phy.davidson.edu/instrumentation/NEETS.htm

    If you did go through NEETS, it will really help refresh your memory. If you didn't, it will be quite helpful. LOTS of reading there. If you spend 8 hours/day reading, it'll probably take you six months to get through all the modules.

    The AAC E-books are accessible from the top menu of every page on this website. Not nearly as thorough as the NEETS pubs, but very handy references. You might want to at least review the table of contents to see what's there.

    Enjoy your time here ;)
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    [Post is now irrelevant; removed]
     
    Last edited: Oct 13, 2009
  4. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
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    I couldn't agree more, Sgt Wookie.
     
  5. davebee

    Well-Known Member

    Oct 22, 2008
    539
    46
    Bill,

    I think you've already got the most important thing - a project you're interested in.

    Your math needs should be minimal to get started, just the occasional multiplication or division, with half a dozen formulas to tell you what values to multiply or divide.

    I'd suggest you get a breadboard with +/- 15 VDC power supplies, a handfull of inexpensive op-amps, resistor and capacitor assortment kits. Make amplifiers and listen to them!

    Experiment until you learn how much gain works, where noise is a problem and how to eliminate it, how to stop your amplifier from oscillating when your circuit is bad, etc. Find circuits on the internet and try them.

    In my opinion, experience is the only way to learn this stuff.
     
  6. hobbyist

    Distinguished Member

    Aug 10, 2008
    764
    56
    Welcome to the forum...
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Yep, welcome to the fray.

    We do not mind questions at any level, so don't be afraid to ask something because it sounds stupid. We have some very good moderators here to keep the more obnoxious types in check, unlike some other forums.

    Check out my blog...

    Bill's Index
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Yes, welcome. The only stupid question is the one not asked.

    As you will see, some responses will come closer to answering your questions than others.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Bill L,
    If you're in need of solderless breadboards or protoboards, check out Marlin P. Jones & Assoc.
    Breadboards: http://www.mpja.com/products.asp?dept=283
    Protoboards: http://www.mpja.com/products.asp?dept=284
    Copper clad: http://www.mpja.com/products.asp?dept=393

    Don't know if you're in need of a cheap bench supply, but you can convert an ATX form factor computer supply to a bench supply for next to nothing; just a few banana jacks, power resistor and perhaps a power-on switch and some LEDs to indicate the supply is live.
    If you don't have a spare ATX supply kicking around, MPJA has some on sale for $13:
    http://www.mpja.com/email/10-13-09a.asp?r=%%ref%%&s=3

    I like those guys because you can find some good deals there, and they ship really fast.
     
  10. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I have interceded and eliminated the off-topic posts in this thread. Please confine your replies hereafter to the topic at hand.

    Welcome to the forum bill l. It is admirable that you have taken the steps to re-enter the electronic world.

    Be sure to check out the AAC forum's ebook at www.allaboutcircuits.com.

    hgmjr
     
  11. rickmartin

    New Member

    Sep 26, 2009
    27
    1
    Why not do yourself a favor and take a course from CIE? They are fully accredited and all of their electronics courses apply toward their degree programs. You sound like you want to just not be able to fix something, but to know WHY. They have an electronics technology course that is well respected and if you complete a program with them you may find yourself qualified for employment in the field. Just a suggestion. http://www.cie-wc.edu/
     
  12. Wendy

    Moderator

    Mar 24, 2008
    20,766
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    That, or he can read the AAC text book for free, and be tutored on the side at the forum (of course, you can get the tutoring for CIE here too). I wound up going to college many years after I started this hobby, but I spent a long time learning on my own.
     
  13. bill l

    Thread Starter Member

    Oct 11, 2009
    30
    0
    i want to clarify that i can troubleshoot to component level, given schematics and some sort of block diagram, that isn't the issue that is bothering me the most, it's remembering formulas and having not worked on analog in such a long time is where the issue lies.

    what i have spent most of the last 8 or so years doing revolves around dealing with this kind of stuff:

    http://www.mi-technologies.com/literature/mit15.PDF

    frankly, while rf can be fun at times ;), i am rather bored with it.
     
  14. Wendy

    Moderator

    Mar 24, 2008
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    RF is a unmitigated PITA, after spending a shift of tweaking a relatively simple filter to match theory I'm ready to do something else. LEDs are more fun, so is high voltage (but I can't do that here). Nothing like sparks and smoke.

    Tuning microwave IMPATT amps with little gold ceramic chips is even less fun, especially with you touch the 130VDC lines with the tweasers.
     
  15. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Sounds beyond tedious. As an alternative to tight control, look into a theremin. It's a "musical" device that works by deliberate detuning the oscillators.

    http://en.wikipedia.org/wiki/Theremin
     
  16. bertus

    Administrator

    Apr 5, 2008
    15,648
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  17. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yeah, RF can be a real headache. ;)

    Here's a "sea story" for ya that you'll appreciate.
    I was a radar/missile systems tech on F-4J & F-4S Phantom II's back in the 70's. Our birds' paint jobs were getting dingy, so the Airframes shop was tasked with giving them a fresh coat.

    Boy, they really looked good with the new paint. But suddenly the RIOs (Radar Intercept Officers) couldn't see an airborne target more than about 5-6 miles away.

    Turned out that the paint that Airframes used had a lead-based pigment. :eek: All of the radomes that had been painted using that paint had to be replaced. Oops.
     
  18. beenthere

    Retired Moderator

    Apr 20, 2004
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    Big oops. You get interesting effects if the deck apes chip the paint on the SPS-10 (surface search) waveguide.
     
  19. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Hah! L or C band, right?

    On a similar note, you get interesting effects when a n00b plane captain tries to recharge the aircraft nitrogen pressure system (3,000 PSI) but instead pressurizes the radar system waveguide (20 PSI max). Pop! Goes The Radar...

    (Airborne radar waveguide must be pressurized with dry air; otherwise arcing will occur at high altitudes.)
     
  20. bill l

    Thread Starter Member

    Oct 11, 2009
    30
    0
    lol....nice
     
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