By Tim Surtell
There are many situations, particularly with large models, where it is advantageous to be able to remove parts of a model for easy access or transportation. If the model uses electrical components, you will likely have the need to join wires from components in a detachable part of the model to wires in another, and will need to choose an appropriate connector.
This article will introduce you to some of the common connectors that are available. Before you decide on which connector to use, always remember to check that it has a high enough current rating for your intended use.
Single way connectors allow for only one join and so are generally used in applications where only a few joins are needed, such as when testing circuits, or as the two power supply unit connections to a model, or for connections that are frequently moved around (as in some designs of control panel).
The most robust type of single pole connector is the banana connector, so-named because of the shape of its plug's spring. You will find there are many different designs incorporating one or more of the following characteristics:
Banana connectors are available in many colours and you can even buy coloured patch cords which are ready-made with one banana plug on each end.
A wide range of connectors are available for joining two or more wires, with each being suited to a specific application. Here are a few common ones that might be useful in Meccano models:
Ideal for connecting a low-voltage power supply unit to a model, barrel connectors which join two wires are a good choice as their design will help avoid shorting out the power supply unit by accident. Normally the outer part of the barrel is connected to 0V on the power supply unit.
You will find there are many different designs incorporating one or more of the following characteristics:
Generally used for connections in audio systems, DIN (which stands for Deutsches Institut für Normung, the German Institute for Standardisation) connectors are circular and come in 2 to 8 way designs, making them useful as a compact connector for models like cranes. The wires are connected via solder tags and the plug has a strain-relief sleeve and clamp to protect the wires. The sockets are either in-line or panel-mountable.
Good for making semi-permanent joins in high-current applications, terminal blocks come in many different designs, some of which are:
While cheap, these connectors are not very robust and can be awkward to assemble, making them only really suitable for low-current applications inside models where they will be rarely disconnected.
The connectors come in three parts: PCB pins, a socket housing and socket terminals.
The PCB pins are mounted 0.1" apart in a plastic spacer and are soldered onto a PCB or piece of stripboard. Any number of pins can be used by simply snapping them off, but the number of connections is limited by the socket housing. Polarised PCB pin headers are also available so that the connection cannot be accidentally made the wrong way around.
The socket housing can be purchased in sizes ranging from 2 to 17 way, and has slots for inserting the socket terminals. These terminals have a spring at one end which engages with the PCB pins, and an area at the other end to solder or crimp a wire.
If you need to make several low-current connections, a D-Sub connector might be suitable as they are available in 9 to 25 way designs. Wires are connected inside to two rows of solder tags, and the hoods, purchased separately, normally have a strain-relief sleeve and clamp to protect the cable.
Source: Electronics in Meccano - www.eleinmec.com | First published in EiM: Issue 4 (June 1999)
Topic: Practical Matters | Created: 05/02/2007 | Last modified: 09/02/2007