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From: Nik on 10 Aug 2010 20:24
"Collecting enough 6n139 Q1 & Q2 Hfe values to be statistically
significant
is, of course, another matter..."

;-)

FWIW, I've hooked the chips up to an Atlas component mini-analyser. There's
a slight drift in Beta (hFE) readings if repeated, but usually no more than
+/- 1%.

Number in sample = 25.

Mean = 101.1
Range 92 ~~110
SD(n-1) = 5.0
.......
Then, given the LED --> PhotoDiode CTR = ~0.0016 (~0.16%)
{OptoElectronics Applications Manual (c)1977 Hewlett-Packard p3.7 and their
6n136 model ;-}

With 6n139 LED cathode connected to Q2 emitter, and both collectors linked,
the Atlas accepted it as an odd darlington, reported the beta.
Mean = 7.3,
Range 6~~9.

Calculating each Q1 beta gave
Mean = 45.1
Range 37~~53
SD(n-1) = 3.6

Disclaimer: These are based on *single* measurements points per chip.
Collecting data over a range of LED currents and Vcc may give significantly
different results. I'll have to do that to get the Early voltage for Q2...

My head hurts...


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