question about transistor substitute

Discussion in 'General Electronics Chat' started by lokeycmos, Jul 29, 2012.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    hello, im gathering the parts to build the attached circuit. my question is, can i sub 2n3773 transistors for the 2n3055? thats all i have on hand right now. i looked at the datasheets, they seem to have similar specs. also would i need to change the 430 ohm resistor at all if i sub? if so what value?
    Last edited: Jul 29, 2012
  2. luvv


    May 26, 2011
    10-40v is a pretty wide range supply voltage...

    Looking at the max base for both,4A base for the 3773 and 7A for the 3055...

    I know very little about how this thing functions,but if I was you I would use some massive heatsinks and double the resistance.

    Slowly ramp up the supply from minimum and monitor them for heat,then you will be able to slowly increase the supply and reduce the resistance till you find the sweet spot where they switch cleanest.

    Looks like there is a lot of variables in that circuit,like that capacitor..I assume its there for resonance and that,as I understand it, takes some trail and error to get it perfect.

    But yea,this is advice from a novice so at the very least my wrong suggestion will attract someone along to correct me =)
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
    There isn't nearly enough information included in that schematic to make the thing work. I know it's a free running oscillator but there's no info on frequency, core material, etc.

    As for transistors: to get an equivalent get one with similar current and voltage ratings, similar current gain, similar mechanical package, similar ft if used as a switcher which this one is.
  4. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    can i get your opinion bill marsden?
  5. #12


    Nov 30, 2010
    Might work better if you'd post the datasheets.
    The 3773 looks close but it has no claim about frequency.
    Still, the 3055 is in stock by the thousands and fairly cheep.