Electricity > Electrical Connectors and Plugs

The photographs and descriptions on this page show some of the various types of connectors and plugs used in conjunction with oscilloscopes, power supplies and other devices which may be used in schools science.

This page may be useful when replacing a certain type of connector or lead.

Photo/Connector	Name	Data
	BNC Male/4mm terminal adaptor	A useful adaptor comprising a BNC plug terminated to twin 4mm terminals in red and black with 4mm sockets. Often used to connect a motor or speaker to an oscilloscope.
	Non stackable 4mm plug	This design enables you to assemble the plug after soldering the lead on. Being non stackable they are only really useful for connecting permanently to equipment such as bells and motors which do not need to be placed in a series or parallel fashion.
	Stackable 4mm plug	Enables connection to lead via a grub screw which means no soldering is required. Many plugs can be stacked to allow series and parallel connections. The stainless steel plug spring lasts a long time and does not corrode. This type is rated up to 10A.
	Shrouded 4mm plugs	Shrouded plugs are used for higher voltage applications They ensure no contact can be made with the live metalwork when not plugged in. If choosing a shrouded plug for high voltages, make sure they comply with IEC standards and are suitable for the range of voltages you are working with.
	13A rubber mains plug	Rubber mains plugs are more rugged and heavy duty than their plastic counterparts. Useful for equipment that is moved about continuously or located in harsh or outdoor environments. Always check that the fuse rating is appropriate for the equipment the plug is connected to.
	3.5mm screened audio plugs	These are often referred to as ‘jack’ plugs and are small versions of the larger loudspeaker plugs. Often used for low voltage speakers and microphones. Stereo plugs are denoted by three separate metal bands on the plug shaft whereas mono plugs have only two separate bands.
	6.35mm (1/4”) jack audio plug	These plugs are commonly used to connect loudspeakers to amplifiers. Note the photo shows a mono plug (with two distinctive metal bands on the plug shaft) Most audio plugs need to be soldered carefully to cable as sound quality may be affected by a poor connection.
	RCA phono plugs	Phono plugs are usually used in pairs to provide stereo sound when connected between CD players, projectors or televisions and amplifiers. Be aware of bent flanges when connecting these plugs as they are easily damaged which may affect sound performance. Phono connectors are usually permanently attached to cables rather than soldered.