Discussion in 'General Electronics Chat' started by PRS, Jan 14, 2009.

  1. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    I just spent the day trying to design an audio amplifier with 1000 volts per volt gain, and though I realize this requires some stabalization, I am thoroughly frustrated. I had transistors that were intermittantly operable, op amps that worked in weird ways, and I could "fix" things by pushing parts around. I think breadboards are overrated. But it could be that my 25 year old board is a dead soldier. I've pushed big leads into tiny holes, I've burned stuff here and there. The board is full of battle scars. Nevertheless, I think I'm done with them.
  2. SgtWookie


    Jul 17, 2007
    Breadboards wear out; their contacts become worn and dirty.

    They can be quite helpful when they are in good condition - but they are electromechanical devices, and like all such things, they eventually wear out - and need to be retired.
  3. John Luciani

    Active Member

    Apr 3, 2007
    I agree that they are overrated -- especially for analog or high speed digital circuits.
    Also you usually end up dismantling one circuit to build another. Sometimes it
    is useful to go back to a previous rev. With Vectorboard you end up with a
    more rugged assembly that you can do more extensive testing on.

    I like Vectorboard 169P84WE, T42-1 and K24A pins. My breadboard hints and
    supply list is at

    (* jcl *)
  4. AlexR

    Well-Known Member

    Jan 16, 2008
    Breadboards are fine as long as one is aware of their limitations.
    Trying to build an amp with 60dB gain is pushing breadboard technology somewhat beyond what it was designed to do.
  5. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    Very interesting. I'd like to see a vectorboard, though, before I bought it. But even so I am tired of buying hardware I can make with a little ingenuity. I just discovered I can make a switch with two pennies. The cost? 2 cents. I can wind my own inductors and that's a savings. I'm working on homemade capacitor fabrication, also resistors. I'm tired of banana plugs and the like -- 2 dollars a pair at least! Sheesh! I can use machine screws with nuts and washers and get the samething done. As far as prototyping goes I think I'm going to go with ugly construction on copper boards. But those boards are expensive, too (though they can be used over and over with ugly construction). Plexiglass work well for perforated needs.
  6. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    I built a common emitter amp with a gain of 300 V/V with no decoupling at all and then watched the output sinewave wobble up and down at 60 or 120 htz.

    And yet, even a breadboard can get a steady 60dB of voltage gain if you are careful. I made a ground up op amp this way -- 3 voltage stages, 1 power stage. But I don't recommend it! :)
  7. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    Tell me about it! :) But I'm tired of buying hardware I can fabricate myself. I'm poor during the winter. I mow lawns for a living -- it's feast or famine for me. Yesterday when I wrote the above I was frustrated. Lately, a o scope probe went kaput and also my "quality" DMM probes. Then I played with xistors and op amps that may or may not have been good -- I couldn't tell because my breadboard is so touchy. This has led to a new project -- a component tester. I picked this hobby up again after a 10 year absence and I'm learning this all over again. :)
  8. davebee

    Well-Known Member

    Oct 22, 2008
    If you want low-cost construction that can perform better than a breadboard, try "dead-bug" construction. Get a surplus sheet of unetched printed circuit board and solder your parts up in the air just off the copper base. Not only do you get a solid groundplane, and much lower stray capacitance between leads, but you can add bypass caps all over the place and get some quite high-speed circuits working. They can look really ugly but can work really well.

    Add sides and a removeable lid made from more circuit board material and you can exclude almost all stray power-line noise and unwanted radio station interference from your circuit, too, if you need a low-noise environment.
  9. PRS

    Thread Starter Well-Known Member

    Aug 24, 2008
    Excellent, suggestion, Dave. I have no problem with a circuit looking ugly as long as it works. Actually, I'm already aware of the dead bug technique and I've used it for radio circuits. I combined dead bug construction with the etching method using a knife to scrape the copper to form small pads on a copper clad board. A group of three makes a place to mount a transistor. Any time I need a node I just scrape a little square out and solder leads to it. I plan to get a Dremmel tool to make the scraping easier. Thanks! :)
  10. atferrari

    AAC Fanatic!

    Jan 6, 2004
    When I started, Paul, I fabricated just what was impossible for me to obtain but went instead into salvaging from whatever discarded equipment I could put my hands on.

    Later I started to consider how much time I was spending to save money. Sometimes it was a LOT to save LITTLE money.

    To a certain point I prefer to buy. Money comes and go but time...

    In line with that I find useless to spend more than one or two days in deciding what chip to use if the difference is just few pesos. For a hobby project it makes no sense. The money I could save is not worth the time spent in doubting. (I dare to say that MOST of the times hobbyists doubt on buying this or that IC where the difference is just 2 or 3 dollars the same amount they could spend later in a sandwich and a softdrink...)

    I could appear as obsessed with loosing time. It is true. That is why I want mine used as better as I can.

    And no, I am not a rich man! :(