Batch of germaniums and need help identifying

[LucifersTrip]

Ok what does e-x mean

10 to the power of x

2.4E-5 = 2.4 x 10 ^ -5

.000024

[Perrow]

But the quick and dirty formula is x * 4 where x is the "gain". In R.Gs example the reading of 247mV means a gain of ~25, multiply with 4 and you get ~100uA 

i don't think that's right

247mV = .247V
.247/2472 ~ 10E-5 which would be ~ 100uA

Yeah, was off on the decimals there, never been comfortable with "scientific" numbers. But the quick and dirty formula of .247 -> ~25 -> 25*4 -> ~100uA is still valid (I'm far more comfortable with multiplying by 4 in my head than dividing by 2472).

[LucifersTrip]

you're actually skipping steps (you can't just write .247 -> ~25)  and it's not as accurate.

.229/2472 = .0000926

you'd have to multiply by .0004 to be equivalent. 

.0004 x .229 = .0000916

I believe you'd always be .0004 x 2472 = .9888 = 98.88% correct

so, the larger the leakage, the more it'd be off....but probably close enough for our purposes.

[Perrow]

but probably close enough for our purposes.

Quick and dirty 

[LucifersTrip]

The fact that it's not 100% accurate is not my main point. The fact that you skipped a step (that you did in your head) will make it insanely confusing to the OP, who's already having a difficult time.

So, to make it clear, using the quick and dirty way, please describe to him how he would get the leakage if he sticks in a leaky Q and reads, say 1.2V

[Perrow]

please describe to him how he would get the leakage if he sticks in a leaky Q and reads, say 1.2V

Sure, sorry if I moved to fast, happens when you see something clearly in your head.

• You read 1.2V
• Move the decimal point two steps to the right, giving you 120
• Multiply 120 by 4 = 480
• This is your leakage (give or take) in uA

You could also go the other way and decide on an acceptable leakage (say 300uA) and divide that by 4 and move the decimal point two steps to the left and have an easy to understand voltage limit (300 / 4 => 0.75V). Over that and it leaks to much under that and you should be ok.

[disabled_shredder]

So I got leakage so to get hfe you subtract leakage x in volts then subtract y in Volts and times that by 100 and get Hfe?