Bayonet Knife

Bayonet mount

Uses

This style of connector was named after its original use for soldiers who need to mount bayonets to the ends of their rifles in a hurry. The same need also applies to photographers who may need to change lenses quickly.

Several classes of electrical cable connectors, including audio, video, and data cables use bayonet connectors. Examples include BNC, C, and ST connectors.

Home light bulbs (230/240 V mains voltage) in India, Australia, Ireland, New Zealand, the UK, Middle East and, in older installations, France, also have this type of "B" base, as well as the Edison screw (E) base used in the United States, Japan and other countries. These bulbs have two pins on opposite sides of the cap; however, some specialized bulbs have three pins (cap designation B22d-3) to prevent use in domestic light fittings. Examples of three pin bulbs are found in mercury street lamps and fireglow bulbs in some older models of electric fire. Bayonet cap bulbs are very common worldwide in applications where vibration may loosen conventional bulbs, such as automotive lighting and other small indicators, and in many flashlights.

Some bulbs may have slightly offset lugs to ensure they can be only inserted in one direction; this is particularly true in bulbs like the 1157 automobile tail-light which has two different filaments to act as both a running light and a signal light. In the 1157 automotive bulb, each filament has a different brightness and is connected to a separate contact on the bottom of the base, the two contacts being symmetrically positioned about the axis of the base (unlike a 3-way medium screw base in which the two filament contacts are a center circle and a ring,) so proper orientation of the bulb is necessary to connect each filament to the correct separate circuit. Newer bulbs use a wedge base which does not have this issue.

Bayonet bases or caps are often abbreviated to BC, often with a number after. The number refers to the diameter of the base (e.g., BC22 is a 22 mm diameter bayonet cap lamp). BC15, a 15 mm base, can also be referred to as SBC standing for small bayonet cap. The lowercase letter s or d refers to whether there are one (single) or two (double) contacts on the bottom of the bulb.

Bulb bayonet mounts

Compact fluorescent lamp with double contact B22d bayonet mount

Incandescent light bulb with double contact B22d bayonet mount, and corresponding socket with sprung connectors

Preceding bulb mounted in the socket

LED lamps with GU10 bi-pin twist-lock mount

Incandescent 40 W BA15d bulb

See also: Automotive lamp types

Type

IEC

DIN

ANSI

B15d

IEC 60061-1 (7004-11)

DIN 49721

BA15d

IEC 7004-11 A

DIN 49720

BA15s

IEC 7004-11 A

DIN 49720

BA20d

IEC 7004-12

DIN 49730

B21s-4

B22d

IEC 60061-1 (7004-10)

BY22d

B24s-3

GU10

IEC 60061-1 (7004-121)

GZ10

IEC 60061-1 (7004-120)

GU24

Pending (Mar 2007)

While G actually indicates bi-pin, those listed above have a twist-lock, but with parallel pins from the end instead of opposing pins on the side.

These are the available sizes in the UK:

Designation

Alternative designation

Contacts

Dimension, etc.

BA5s

1

5 mm

BA7s

1

7 mm

BAX9s

1

9 mm

BA9s

Miniature bayonet cap (MBC)

1

9 mm

BA15d

Small bayonet cap (SBC)

2

15 mm

BAX15s

1

15 mm

BA15s

Single centre contact (SCC)

1

15 mm

BA20s

1

20 mm

BA20d

2

20 mm

BA21d

2

21 mm

B21-4

21 mm 4 pin

BA22d

Bayonet cap (BC)

2

22 mm

BC-3

Bayonet cap (BC)

2

22 mm 3 bayonet pins

B22d-3

2

22 mm double ended (railway)

BX22d

2

22 mm

Of these, only the BC (BA22d) is widely used in homes.

References

^ see http://technical.greenstock.co.uk/KYBLampBases.htm

IEC 61184: Bayonet lampholders, International Electrotechnical Commission, 1997. (also: BS EN 61184) specifies requirements and tests for the B15 and B22 bayonet holders for light bulbs used in some Commonwealth countries

See also

Bipin

Arri bayonet

Lens mount

Joseph Swan

Bayonet - a type of knife that attaches to a rifle.

External links

GU-24 Goes Mainstream

Line-voltage Socket Design Competition (GU24)

Categories: Fasteners | Light sockets
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Matrix Tactical M-9 Bayonet/Knife Review