For the eye, a detailed engine with moving pistons is installed in the original construction. If you omit
the rear crane construction and the winch, you can instead use the Unimog to mount a snow plow that
consists of the parts of the cargo bed.
1.1 Sometimes practical: use Lego spare parts warehouse
Especially in the case of Lego special construction projects – regardless of whether with or without
home-made electronics – it sometimes happens that exactly the Lego-Technic module can not be found
at the time when it is needed. But sometimes, even with a freshly purchased Lego Technic set, it can
happen that one or the other Lego building block is missing – for whatever reason. For this purpose, Lego
has its own service and quality assurance website on the Internet, where you can report such complaints
and receive the required spare parts within a very short time free of charge.
Especially with older Lego kits spare parts are sometimes no longer available at Lego or no longer
available, for example because they are no longer installed in any sets and therefore no longer
produced. In this case, there are some Lego parts dealers on the Internet who also have rare Lego spare
parts available for a fee, of course – ideal for own creations that require special Technic components.
Such parts are also needed when it comes to replicate as faithfully as possible a model and implement,
for example, a functional controller or an alternative gear block for large ground clearance and four-
speed gearbox with engine control. Then the standard components in the box are usually not enough.
In order to equip the Lego self-built model with technically sophisticated electronic functions, you need
a few electronic bases in addition to the matching Lego-Technic components, so that the retrofitting of
the Lego bricks with the self-built electronics works right away.
Circuit, voltage, current
In order to be able to use electronics in a Lego vehicle at all, it needs some background knowledge. The
basis of electronics is based on one or more electrical circuits. This usually consists of a voltage source or
current source, a conductor (for example, a plug board or wire) and a consumer (LED, motor, etc.) with a
so-called internal resistance, which ensures that drops inside the load voltage. Before you dive into the
depths of the circuits and controls, you should again recall the school physics: The electrical voltage –
called U – indicates the difference in charges between two poles. Voltage sources always have on one
side of the positive pole with a lack of electrons and on the other side of the negative pole with an
excess of electrons. The difference in the quantity of electrons is called electrical voltage. If the positive
pole and the negative pole are connected, the electrons discharge, which causes the current to flow.
Technical vs. physical current direction
If, for example, an LED and a resistor are connected to the voltage source via the plug-in board, the
electric current flows from the negative pole via the LED to the positive pole (physical current direction).
Of course, the traditional current direction (technical current direction) goes from plus to minus, so also
in circuit diagrams:
The sense of direction of currents and voltages is given in principle in the technical current direction by
reference arrows from the higher to the lower potential.