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Having had to repair “in situ” other peoples electrical connections on their locos I feel it advisable to state that twisted together wires and insulation tape is not going to last for long. A soldered plug and socket connection a far better bet!

There are some very cheap and reliable connectors available for use in our scale that are easy to use and make life at the repair station a lot easier to manage. Most of these require the use of a soldering iron, typically around 25W, some solder and a little patience.

The DIN standard plug and socket.

This has been around since WW1 in various forms. It means German Industrial Number. The one most useful to us will be the DIN 7-270 range. This has 7 pins arranged in an arc of 270 degrees. This in socket form will take DIN 3-180, DIN 5-180 and DIN 7-270 plugs. The 7 pin ones are the cheapest as they are not “trendy” for use in audio and MIDI equipment. The plastic “domestic” type will take about 1Ampere per pin whilst the metal “industrial” type take 5Amperes per pin. Maximum voltage across the pins should be limited to 24Volts in the domestic version. Sheathed connections up to 48Volts per pin are possible with the industrial type. The domestic type are not waterproof but can be used in dry environments, such as under cover. In the event of “known bad weather problems” it is easy to dip the pins into grease to ensure water proofing. I use them for connecting signals.

The 3.5mm RCA jack connector.

This is familiar to anyone with a set of headphones. The current capacity of this connector is around 0.5Amperes. This does not stop it being used for on board battery charging as typical charging currents are 0.1 amp hour loading for NiCd and 0.25 amp hour loading for NiMH. This means that it can be used for charging a power pack of 5Ah for NiCd and 1.25Ah for NiMH. When wiring the large external ring is positive and the pin negative. There are 3 ring connectors but thay are far too fiddly for our use, but again the ring and pin polarities still apply.

The Canon XLR connector.

This is very common in stage audio equipment as the heavy plugs and in line sockets can be stood on or castors rolled over them with no effect. But this is not where they originated. The U.S.A.A.F. used them as a standard fitment for the Convair B36 Bomber, (six turning four burning). This was designed to take 25Volts at 1 to 3Amperes and to literally be bulletproof! It is available in 3 to 10 pins and features a locking tab that grips the connector firmly. In order to ensure reasonable safety I would recommend that a (male) chassis pin socket be fitted at the battery charging end. This is the reverse of how a “music” system would be wired.

The Neutrik “Speakon” connector.

This is a plug and socket arrangement that has NO external connectors. Instead the tubular plug fits into the socket and the connectors only wipe to engage when the plug is rotated to lock it in the socket. They are available in a number of configurations for both DC and AC systems. Typical Neutrik connectors will take 40Amperes at 100Volts, this is standard stage PA line voltage. This makes it ideal for fast charging or carrying a number of power leads.

The 0.1” pin connector.

This is most commonly found on circuit boards and is used to couple the projecting pins with. It is possible to obtain this connector in 1, 2, 4 or 8 connections. The pin is crimped to the cable then it push fits and locks via a simple projecting spur. Once “in” it will never ever come “out”… Therefore ensure that you have everything correct! This is most common on R/C systems and other control PCBs. They are robust -but fiddly.

The “Tamiya” connector.

This has become a generic term like Hoover. The connector has a rounded “D” and a square male plug, the same with the female side. There is a latching tab on the male. These feature the same crimp and spur idea as the 0.1” connector except on a far larger scale. The connector is commonly found on the end of “Tamiya Race Packs” of 14.4 and 7.2 Volts. Whilst the crimp is perfectly satisfactory I personally prefer to crimp and solder the connectors before insertion. Again the same warning as above make sure you put the right cable in the right shaped hole. Square is positive. The connector comes in two sizes with a 10Ampere loading.

The "Molex" connector.

This is a common PC power connector similar to the Tamiya but has a far higher current rating. These are used to connect hard disc drives and other power peripherals. Again a crimp connector with locking spur is used to terminate the cables into the plastic plug or socket. These are very useful if you need to produce a "buss bar" type installation of several motors along a series of bogies.

The Chocolate block.

I don’t know of anyone who has not used one of these but there are a few warnings that should be given. These are best used with either solid or soldered sealed wire. This will prevent stray “fly ends” causing shorts. The white bendy polythene domestic ones are rated at only 5Amperes.

The 1/4” spade connector.

These are so familiar to anyone with a motor car that I will not bother describing them. Modern ones come with a plastic sheath which is crimped onto the bare end of the wire. This does not ensure a robust mechanical connection though and they can break loose. I prefer to buy loose spades and sheaths and then crimp and solder before installation. Ordinary care should be taken that all feeds from power circuits have shielded connectors. They are not designed to take a high wattage.

The colour coded RED ones at 12Volts are rated at 5Amperes and at 24Volts only 3Amperes.

The colour coded BLUE ones at 12 Volts are rated at 10Ampere and at 24Volts 7Amperes.

The colour coded YELLOW ones at 12Volts are rated at 25Amperes and at 24Volts 12Amperes.

The ScotchLok connector.

These are primarily automotive connectors. They have little use for a loco. However they are very useful for external weather resistant connections.

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Page last modified on April 02, 2018, at 05:10 PM