Transistors - Understanding Datasheets

[UTMonkey]

Dear All,

Went to my local electronics shop today to purchase some transistors, the shop keeper asked what type. I shrugged my shoulders and said the only thing I knew, "some NPN ones.."

At that point my cover was blown, the guy looked at me a bit strange and immediately knew i was a complete novice.

Anyway, I am now the proud owner of half a dozen BC182 NPN transistors.

I have looked up the datasheet for these:-

https://www.electro-tech-online.com/custompdfs/2007/10/BC182.pdf

I am now ready to tinker! before i start I could do with:-

1. Understanding what the information on the sheet means, could anyone direct me towards some information which helps me interpret this.
2. What is the critical stuff I should look for on this sheet?
3. What can I take as gospel truth from this sheet. Previous emails on these forums indicated that transistors vary from each other (despite the same number)?

Don't misunderstand me, I know enough about transistors to throw them in a circuit (and I mean throw!), but I want to make sure that I am able to design a good enough circuit with components correctly chosen.

Many thanks in advance

Mark

 

[audioguru]

The maximum allowed voltage, current and power dissipation is spec'd.
The current gain varies from 120 to 500 (I can't read at what current).
The saturation voltage max of 1.2V is high but will be lower with more base current.
The current Gain Bandwidth Product of 150MHz means it can be used in an FM transmitter.
The pins are in the European order.

 

[UTMonkey]

Thanks,

The absolute Maximum Ratings make perfect sense. It the "Characteristics" that are confusing.

I didnt realise that the gain of a transistor altered depending on the voltage and current at the Collector.
in the sheet it says:
V(CE) = 5V, I(C) =10uA = min gain 40
V(CE) = 5V, I(C) = xx (obscured) = min gain 120
V(CE) = 5V, I(C) = 100ma = min gain 500.

What a spread!

One question though, why would the saturation voltage be lower with increase base current?

Thanks

 

[Nigel Goodwin]

One question though, why would the saturation voltage be lower with increase base current?

Because you're forcing the transistor harder ON.

 

[UTMonkey]

gotcha! ;-)