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Germanium Transistor musings

T

Tim Williams

Jan 1, 1970
0
I have a TO-3 size Tung-Sol 86X2 germanium transistor, removed from, I
believe, a low voltage regulator circuit in an organ (transitional age: 6 x
6CG7 master oscillators for the 12 individual notes, plus a lot of pairs of
TO-5 germanium transistors for frequency division flip-flops to generate the
lower octaves). Anyways, out of idle curiosity I hooked it up. Here's what
I got.

Type: PNP germanium power transistor, pins as indicated on underside
case = collector).

Maximum ratings:
(Values at roughly 20-30°C. Values are absolute because I don't feel like
writing negatives on every single parameter.)
Vce = 22V (B open)
Vcb = 30V (B, E grounded)
(Zener type characteristic; no avalanche behavior noted.)
Veb > 36V
Maximum Ic, Ib unknown.

Didn't measure leakage currents.
Didn't measure capacitances.

Operating Characteristics:
Vc = 12V, Ic = 266mA, Ib = 1.7mA
DC gain (beta) = 150 (200 at 50°C)
Vce(sat) = 0.22V (Ib = 30mA, Ic = 1A)
Vce(sat) <= 0.5V (Ib = 40mA, Ic = 2A)

Switching Characteristics:
(Square wave input, tr = tf = 50ns. Base resistor 47 ohms, collector load
15 ohms, supply +15V, Ic ~= 1A when ON.)
At beta = 10 (Ib(ON) = Ib(OFF) = 100mA):
Delay time (from input rising edge to change in Ic), td = negligible
Collector rise time, tr = 3.5us
Storage time (from input falling edge to change in Ic), tstg = 1us
Collector fall time, tf = 2.4us

At beta = 100 (Ib = 10mA, Ic = 1A):
td = negligible
tr = 50us
tstg = 4us
tf = 12us

Suprisingly, that's not too bad, at least at lower gain values. You could
get what, 50 maybe 100kHz bandwidth from an amplifier using these! It would
be guitar-player-friendly too. ;o) Other than that, you could make use of
the more than doubled headroom and build low-frequency inverters to run on
single cell PV setups for instance (such a circuit appeared in Electronics
Now, with the author none other than Fred Nachbaur, of McTube fame).

Tim
 
R

Rich Grise, but drunk

Jan 1, 1970
0
.
[PNP Ge transistor characterization]
....
Suprisingly, that's not too bad, at least at lower gain values. You
could get what, 50 maybe 100kHz bandwidth from an amplifier using these!
It would be guitar-player-friendly too. ;o) Other than that, you could
make use of the more than doubled headroom and build low-frequency
inverters to run on single cell PV setups for instance (such a circuit
appeared in Electronics Now, with the author none other than Fred
Nachbaur, of McTube fame).

So, what's the question? I just noticed the other day that in my parts bin
I have 8X TIP33C, and almost 100X MPSA06. So what? ;-)

Cheers!
Rich
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