Tycobrahe Octavia negative ground mod tranny substitutes?

Started by Sirppi, June 26, 2010, 05:29:18 PM

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Sirppi


petemoore

 5087 is PNP high gain
  The 4401 is lower gain, somewhere around like a 2n2222.
  Q2 is a buffer stage, any NPN bipolar will do this.
  Q3 is a gain stage, but it also has to drive the xformer, perhaps this is the reason a high gain transistor isn't recommended here.
Convention creates following, following creates convention.

Sirppi

Could i use 2N3904s or 2N4124s for the Q2 and Q3? I'm ordering from Uraltone, could you give me a hand on choosing the right trannies?  :icon_mrgreen: http://uraltone.com/kauppa/index.php?cat=c64_Transistors.html&XTCsid=9glkuk9vapemoq0rkr7pl79kc6

petemoore

  the page didn't load left so I couldn't see the right column...where the transistor numbers are...
 I did see one that said ''hfe 100''
 The one under it said ''Min Hfe 100'' these are only ballpark #'s what you'll find you've got with a handful measured for HFE in your DMM will show is that the gains range, 2n3904's are like 300-500 hfe [something like that], 4401's range from 100+hfe up to 350...again or something like that.
 Since only the third transistor is going to 'notice' [middle stage is buffer, anyole trasistoerli of an NPN type device will work there].
  Q3's driving a transformer, might be interesting to see what a buffer would do right there...anyway, low or lowish gain ''just seems'' like a good choice for that position [since it's suggested as 2n4401 and..there's that tranny].
Convention creates following, following creates convention.

Sirppi

i have some BC558s and BC559s hanging around, could i use one of them for the Q1?

petemoore

  Whoops, Q1 is a splitter, but I think the BC's you mentioned are fairly high gain, as long as they're the correct polarity, 'a' bipolar will work.
  don't know if we need to know more about this transistor work [Q1, other than use the correct polarity, a high-ish gain bipolar.
Convention creates following, following creates convention.

Sirppi

I only have 'B's and 'C's of those two  :( so i have to select also the Q1 from uraltone....