ВЭФ 12 (Astrad VEF 12 Project) - including a transistor tutorial

[Mark Hennessy]

I would start first on PNP germanium because these were the first used and current doesn't leave the N type base. It sinks current at the base. Bear in mind transistors are new to me (about 7 weeks). So, start with the basics is best, PNP first.

Actually, I strongly disagree with this.

In a PNP transistor, current is sourced from the base. An NPN transistor sinks current at the base.

If you're familiar with valve circuits, NPN is best.

When it comes to understanding them, there's actually no difference - they both behave the same. If people find a difference between them, they always prefer NPN and struggle (only slightly) with PNP. By sticking to this mantra of "PNP came first", you're just making life difficult for yourself.

However, what it boils down to is just the difference between positive and negative numbers.

Also with valves phase is very important and I have to apply this to semiconductors too. What is the phase of cathode anode voltage in relation to the anode load of a triode? That is with signals on the grid. What is the cathode grid phase? I need the full picture to get the details.

You're asking about AC here. Are you sure you're ready to get onto this?

Here goes:

The collector current is, very roughly, proportional to the voltage at the base-emitter junction.

To be more precise, there is an exponential relationship between the two, as described here: https://en.wikipedia.org/wiki/Bipolar_ju...Moll_model

So, if the base-emitter voltage increases, the collector current also increases. So what happens to the voltage at the collector - up or down? Over to you - everything you need to know to answer this question is contained in this post.