Applied Electronics - Outcome 1 & 2 Practice Questions

Here are some questions for you to try over the October break. I may put some more up later, but here are some to get you started.  Remember that a lot of the NAB is description, so put extra effort into the describe questions!

 

For the question above, please note that ID should be 10mA, not 20mA, the supply voltage should be 24v, and that the thermistor is a type 4 thermistor.  Sorry for the edit! 

Applied Electronics - Outcome 3 - Boolean Algebra

Boolean Algebra is another way of describing a logic truth table or circuit.  Just like any other Algebra you need to know the operators to be able to write the equations.

They are:

You need to be able to go between an English statement, a truth table, a logic circuit and a Boolean expression.

From a Boolean expression you can work out which logic gates you will need to perform each part:

To derive a Boolean expression from a truth table you must identify when the output is on, writing an expression for these lines and then combining each of these expressions with an OR operator.

You can also derive a Boolean expression from a circuit diagram by following the signal using the original inputs and the Boolean operators:

Applied Electronics - Outcome 3 - Logic

Outcome 3 is logic.  It is not vastly different from Intermediate 2, but they may ask you to design a more complicate circuit and look at NAND or NOR equivalents.

Firstly lets consider this circuit:

The first thing we should be able to do is draw the truth table for it:

A and B are our two inputs, but we could put in points to help us after the AND gate (C) and after the NOT gate (D).

A B   C   D   Z
0 0     0    1   1
0 1     0    0   0
1 0     0    1   1
1 1     1    0   1

We could also draw the NAND and NOR equivalent circuits.  By taking one gate at a time we can draw the equivalent for that gate, and then connect them as the original circuit is.

The benefit of designing a NAND equivalent is that we then only need one type of chip.  This makes it cheaper as we have simplified the circuit to only need one type of IC, and we could get a smaller end product as we need to include less ICs.

Here is the NAND equivalent of the above circuit.  Notice that there are two inverters in a row so they cancel each other out.  Instead of drawing the whole circuit again, you can simply put a line through them.

This has really simplified the circuit!  Instead of needing 3 ICs we now only need one, and we only need to wire in two gates.

This is the NOR equivalent.

This is less effective for this circuit as it has actually given us more logic gates to wire.  But we do only need 1 IC instead of 3.

Applied Electronics NAB

Your NAB for Applied Electronics will be on:

Friday 28th October

You will need to be able to:

•  Carry out calculations and describe Transistor and MOSFET circuits
• Identify, describe and carry out calculations for the different configurations of Op-Amps