>Dwayne,
>Have you considered using a Direct Coupled Compound (DCC) arrangement? This
>has the gain advantage of a Darlington, but has only one forward
>diode drop (Vbe drop). A DCC has gain = Beta1*Beta2. The 'device' has the
>characteristics of the input transistor. A disgusting ascii drawing follows.
>
>*****************************************************
>Direct Coupled Compound (DCC). "NPN" Equivalent Shown.
>One Vbe forward diode drop. Gain=Gain_npn*Gain_pnp
>
> Effective Collector
> |
> |
> PNP V (E)
> |/
> ------|
> NPN |/ |\
>Base--------| | (C)
> |\ |
> V |
> | |
> --------*
> |
> |
> Effective Emitter
>
>*******************************************************
>Add this to your 'collection'.
>
>Hope this helps.
>Fr. Tom McGahee
>
>>
>> > Hi!
>> >
>> > I'm looking for recomendations for TO-220 NPN and PNP transistors that have
>> > moderate current gains at about 1 Amp. Should be good for at least 40V,
>hfe
>> > greater than 100, reasonably robust. My old standbys TIP31, TIP32, TIP41,
>> > TIP42 don't have enough gain and the TIP120 - TIP127 are darlingtons and
>> > have too much voltage drop. I don't need complimentary pairs so unmatched
>> > parts are fine. North American part numbers preferred. Any thoughts?
>> >
>> > Thanks!
>> >
>> > dwayne
>> >
>> >
>> > Dwayne Reid <
.....dwaynerKILLspam
.....planet.eon.net>
>> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA
>> > (403) 489-3199 voice (403) 487-6397 fax
>> >
>
>