RF COAXIAL CONNECTORS
In this section we will discuss about a type of connector which is specifically designed to couple signals only, and the signal referred to the connector is nothing but RF signals. Coaxial connectors are one of the important components of an RF system. Coaxial connectors are specially designed components for connecting and disconnecting the device's RF transmission line. Coaxial connectors have been widely used to couple RF energy from device to device since the 1940s. The first coaxial connector developed was the Ultra High Frequency (UHF) connector designed by Amphenol. The coaxial connector is always cylindrical in shape and the inner metal connector and the outer metal connector share a common axis and hence it is called coaxial connector.
The coaxial connector is always found at the end of a coaxial cable. Coaxial cable was invented in the 1880s and is still the best design for carrying RF energy. It has an internal copper core separated from the external metallic shield by an insulator.
Fig. 1: Image showing structure of a coaxial cable
The coaxial connector is actually an extension of the coaxial cable maintaining the same coaxial geometry. There are a wide variety of coaxial standards that differ in their specifications. Each of them is specifically designed for a given operating frequency, attenuation, insertion loss, environmental conditions, power handling capacity, size, shape, strength, weight, cost, etc.
Figure 2: Image showing a coaxial connector at the end of coaxial cable
For efficient operation of an RF system, the designer must have a good knowledge of the electrical specifications of the connector, since RF energy enters or leaves the system through the coaxial connector and therefore performance depends heavily on the specifications of the connector. Before we move on to the discussion about different RF connectors, let us look at some of the specifications that are very significant for RF coaxial connectors.
Characteristic impedance
CHARACTERISTIC IMPEDANCE
A coaxial cable has an inner conductor and an outer conductor separated by insulating material between them. Any two conductors separated by an insulating material will generate a capacitance between them, and we generally refer to this unwanted capacitance as parasitic capacitance. Furthermore, any conductor of significant length has an inductance. With this knowledge we can assume both conductors of the coaxial cable as continuous inductors with capacitance between each point of the two conductors.
We are not considering the actual resistance of conductive materials, which is negligible, but for high frequency applications we must take care of inductance and capacitance. The equivalent of infinite length coaxial cable transmission line with parasitic capacitance and inductance is shown below:
Figure 3: Equivalent circuit diagram of coaxial cable
At infinite length, the effect of these inductances and capacitances is purely resistive, meaning the effect of all the resistors and capacitors is equal to the effect of a single resistor connected to the end of the coaxial cable. As the effect at infinite length can be considered resistive, the resistance that the coaxial cable offers to the input signal is independent of the input frequency. We call this resistance the characteristic impedance of the coaxial cable.
The characteristic impedance of a coaxial cable is very important with regard to connector design, because for maximum power transfer from the coaxial cable to the connector the connector must have exactly the same impedance as the coaxial cable.
IMPEDANCE
According to the maximum power transfer theorem, maximum power is transferred from a source to the load only if the impedance of the source and load is the same.
Fig. 4: Equivalent circuit diagram of a coaxial cable connected to a coaxial connector
In the case of coaxial cable and coaxial connector, the maximum power of the coaxial cable is transferred to the coaxial connector only if the characteristic impedance of the coaxial cable and connector is exactly the same. The characteristic impedance of coaxial cable is resistive in nature and the impedance of the connector is also resistive and is represented in ohms.
Typically coaxial connectors have an impedance of 50 ohms. The reason for this value is that the connector introduces signal attenuation when passing the signal from the coaxial cable to the device and the theoretical impedance corresponding to the minimum attenuation for the coaxial connector of a 50 ohm coaxial cable should be 77.5 ohms. But theoretically the maximum power transfer occurs at 30 ohms, and taking the average of 77.5 and 30 we obtain 53.75. Rounding the value, the impedance is standardized at 50 ohms. Impedance depends on connector geometry and insulating material parameters.
Voltage Standing Wave Ratio
ROE
When coaxial cable does not terminate in a connector with matching impedance, this will result in 'reflected wave' in the cable. This wave reflected from the cable interferes with the transmitted wave and results in 'standing wave'. Let's consider a practical experiment that will help you understand the concept of reflected and standing waves.
Fig. 5: Image showing experiment illustrating the single wave transmitted on the string
As shown in the figure above, take a rope and leave one of its ends on the ground. Lift the other end and tap gently. You can see the waves starting in your hand traveling to the floor and dying before reaching the floor. Any waves transmitted by your hand are lost before they reach the ground due to the rope's internal resistance to bending, so no waves come back. In this case, all the energy is transmitted only and therefore there are only transmitted waves in the string. This state of the string is equivalent to a long coaxial cable terminating in an impedance-matched connector.
Now tie one end of the rope to anything solid so that the length of the rope is much shorter than in the previous case.
Figure 6: Image showing experiment illustrating the transmitted wave and the reflected wave on the string
Lift the other end parallel to the floor and gently whip the rope once. You can see the wave traveling from your hand to the solid object. If the wave is not dead before it hits the solid object, it will be reflected off the object and travel backwards. We call this wave a reflected wave. This state of the string is equivalent to that of coaxial cable terminated in a connector of mismatched impedance.
When the waves reflect back toward the source, they interfere with the transmission waves and result in standing waves, as illustrated in the following experiment.
Figure 7: Image showing experiment illustrating standing wave on the rope
Tie both ends of the rope to solid objects and blow gently from one end continuously. The rope continuously absorbs energy from one end and transmits it to the other end, which will be reflected back to the same end. These continuously reflected waves interfere with the continuously transmitted waves, producing standing waves in the string.
We learned about transmitted wave, reflected wave and standing wave. Now, Voltage Standing Wave Ratio (VSWR) is a measurement of the standing wave effect in a coaxial cable. It is the ratio between the amplitude of the reflected wave and the transmitted wave.
VSWR = reflected wave amplitude / transmitted wave amplitude
Normal connectors have a VSWR between 1 and 1.5. High VSWR values for a connector mean that the connector is not compatible with 50 ohm coaxial cable. This occurs due to variations in the impedance value of the connector in relation to the matched impedance of the cable. This impedance variation occurs due to the effect of capacitance and connector geometry and this variation depends on the operating frequency. Consequently, VSWR is usually specified over a frequency range.
INSERTION LOSS
Insertion loss is another parameter that affects the signal transmission efficiency from the connector to the device. A significant amount of amplitude loss occurs in the signal at the connector due to variations in impedance. The amount of these losses is called insertion loss, expressed in dB.
Insertion loss depends on the properties of the connector's insulation materials and conductors.
A designer must consider the effect of coaxial connector insertion loss and must compensate for the effect when designing the RF system.
RF LEAKAGE
A significant amount of RF energy generally radiates from the connector itself. Because of this, the signal attenuation occurs before coupling it to the device. The amount of RF energy radiated before coupling to the RF system is called RF leakage and is expressed in dB.
RF leakage mainly occurs through the slots or holes in the connector body or may occur due to less tight mating of the male and female connectors.
A designer must also consider the effect of RF leakage from the coaxial connector and must compensate for the effect when designing the RF system.
This is all about the common specifications found specifically in the coaxial connector datasheet, in addition to the common connector specifications we have already discussed.
Now let's find some of the common coaxial standard connectors and their details.
SMA and NEILL connectors
SMA CONNECTOR
The SMA stands for “Subminiature A”. The SMA connector is a commonly used RF coaxial cable connector. It was designed by Bendix Research Laboratories in 1958 for use with .141 (RG-402) semi-rigid grips. They are designed to operate at 18 GHz frequency. The connector has a small diameter compared to other coaxial connectors.
Figure 8: Image of the SMA male and female connector
SMA connectors have a threaded coupling and are made of brass contacts separated by Teflon insulators. SMA connectors have low reflection property, 50 ohm impedance and low VSWR. They are suitable for broadband operations and versions of these connectors are available up to 27 GHz. SMA connectors are very strong, durable, small in size and low cost coaxial connectors.
SMA connectors can be found on amplifiers, attenuators, filters, mixers, oscillators, switches, etc. SMA connectors are widely used in military applications and RF systems, including Strip Line and Micro-strip technology.
Sample Specification:
Impedance —————————– 50 ohms
Frequency range ——————— 0–18 GHz
Voltage rating ———————— 500 V peak
Dielectric strength ————- 1000V RMS
ROE ———————————– 1.05 +
Contact resistance ——————- 2.0 milliohms
Insulation resistance —————- 5000 Megohms
RF Leakage ————————— -90 db min.
Insertion loss db max. ————- .06
N CONNECTOR
The N-type connector is another connector that has proven its usefulness in RF technology. The N-type connector has been in use since the 1940s in RF devices. They were designed to operate at the 12 GHz frequency. The name N connector is named after Paul Neill of Bell Labs, who invented this connector.
Figure 9: Image of the N-type male connector
Fig. 10: Image of the N-type female connector
It has a threaded coupling interface and generally has an impedance of 50 ohms. The contacts are made of brass and separated by insulators such as tetrafluoride resins. The interface used in these types of connectors is nothing more than the air itself. They are larger than SMA connectors.
Type N connectors are used on large coaxial cables and in weatherproof applications.
N connectors are widely used in military communication equipment, microwave local area networks, etc.
Sample Specification:
Impedance —————————– 50 ohms
Frequency range ——————— 0–10 GHz
Dielectric strength ————- 1500 V AC/1 minute
ROE ———————————– 1.2
Contact resistance ——————- 3.0 milliohms
Insulation resistance —————- 5000 Megohms
TNC and SMC connectors
TNC CONNECTOR
Threaded-Neill-Concelman (TNC) connectors were designed in 1956. They are specifically designed to withstand extreme vibrations. TNC connectors are medium-sized connectors that can operate up to 12 GHz.
Fig. 11: Image of the TNC type male connector
Figure 12 : Image of the TNC female connector type
TNC connectors use threaded coaxial coupling. They are used in military and aerospace applications as they are designed to withstand extreme pressure and vibration.
Sample Specification:
Impedance —————————– 50 ohms
Frequency range ——————— 0–11 GHz
Working Voltage ——————— 500 Volts rms.
Dielectric strength ————- 1500V RMS
ROE ———————————– 1.3
Contact resistance ——————- 1.5 milliohms
Insulation resistance —————- 5000 Megohms
SMC CONNECTOR
The SMC stands for “Sub-Miniature C” connector. It is similar to the SMB connector, but is designed for higher frequencies. Similar to other types of connectors, the SMC has an impedance of 50 ohms and is designed to operate at a frequency of 10 GHz.
Fig. 13: Image of the SMC type male connector
Figure 14: Image of the SMC female connector type
Typically brass, beryllium copper and copper are used as conductive materials and Teflon is used as an insulating material. The SMC is identical in structure to the SMB, but has threads for threaded coaxial coupling.
The threaded structure and small size make them suitable for operation in environments such as aircraft, space shuttle, etc. They are widely used in military and non-military applications.
Sample Specification:
Nominal impedance ——————— 50 ohms
Working voltage ————————- 335 volts rms
Frequency range ————————- 0 to 10 GHz
Insulation resistance ——————– 1000 megohms min.
Contact resistance ———————– 12 milliohms
Dielectric withstand voltage —— 1000 volts rms
RF Leakage ——————————– -60 dB min
RF insertion loss ————————– 0.25 dB max.
MB and MCX connectors
SME CONNECTOR
SMB stands for “Sub-Miniature B” connector. It is designed to operate up to a frequency of 4 GHz. Unlike other coaxial connectors, it is designed for quick connection and disconnection.
Figure 15: Image of female and male SMB type connectors
SMB connectors with 50 ohm and 75 ohm impedance are available. It has a spring-like outer structure for easy connections. SMB connectors are useful in environments with moderate vibrations. They are also suitable for circuit miniaturization and dense internal packaging applications. They are commonly used in PCBs with flexible cables and used in inter- or intra-board signal transmission.
Sample Specification:
Nominal impedance ——————— 50 ohms
Frequency range ————————- 0 to 4 GHz
Voltage Rating —————————- 500 VRMS Max.
Current rating —————————- 1.5 amps DC max.
Insulation resistance ——————– 1000 megohms min.
Contact resistance ———————– 6 milliohms max.
RF Leakage ——————————– -55 dB min
RF insertion loss ————————– 0.30 dB max.
MCX CONNECTOR
The Micro CoaX (MCX) connector was designed and developed during the 1980s. It was specifically designed for applications where size and space savings are critical. The MCX connector is designed to operate up to a frequency of 6 GHz. MCX connectors are available in 50 ohm and 75 ohm versions.
Fig. 16: Image of the MCX type male coaxial connector
Figure 17: Image of the MCX type female coaxial connector
The design structure of MCX is similar to SMB, but it is approximately 30% smaller in size than SMB connectors. Just like SMB, the MCX connector also uses the snap-on coaxial connection method.
MCXs are widely used in many commonly found microwave modules where miniaturization is very important, including Global Positioning Systems (GPS), automotive, information system, market communications, cellular telephony and data telemetry.
Sample Specification:
Impedance ————————————— 50 ohms
Frequency range ——————————- 0–6 GHz
Working voltage ——————————- 335 VRMS
Dielectric withstand voltage ———– 1000 Volts
VSWR —————————————— 1.3 max. 6GHz
Contact resistance —————————- 5.0 milliohm max.
Insulation resistance ————————- 5000 megohms
Insertion loss ———————————– 0.1 dB max.
BNC and UHF connectors
BNC CONNECTOR
The Bayonet-Neill-Concelman (BNC) connector is named after the inventors of the BNC connector Neill and Concelman. Bayonet is a unique coupling method used in this type of coaxial connectors. They are designed and developed in the 1940s. BNC connectors are available in 50 ohm and 75 ohm impedance versions. They are designed to operate at a maximum frequency of 4 GHz.
Fig. 18: Image of BNC male coaxial connectors
Figure 19: Image of BNC female coaxial connectors
The BNC connector is identical in design to the N-type connector, but has a bayonet locking mechanism for mating. This bayonet lock provides a completely firm and secure fit and makes the BNC connector look totally different from other types.
BNC connectors are used with medium sized coaxial cables and have wide range of applications like flexible networking, instrumentation and computer peripheral interconnections, etc.
Sample Specification:
Impedance ————————————— 50 ohms
Frequency range ——————————- 0–4 GHz
Working voltage ——————————- 500 VRMS
Dielectric withstand voltage ———– 1500 Volts
VSWR —————————————— 1.3 max. 6GHz
Contact resistance —————————- 1.5 milliohm max.
Insulation resistance ————————- 5000 megohms
UHF CONNECTORS
Ultra-high frequency (UHF) connectors are the most popular among coaxial connectors. It was invented at Amphenol in 1930. Unlike all other coaxial connectors, the UHF connector has variable impedance. Due to this variable impedance, UHF connectors can only be used up to a maximum frequency of 500 MHz. They have a peak voltage of 500 volts. There are also Mini-UHF connectors that are smaller than the UHF connector and can be used up to a maximum frequency of 2 GHz.
Fig. 20: Image of the Circular Connector
Figure 21: Image of the male and female mini-UHF coaxial connector
Fig. 22: Image of the male UHF coaxial connector
Fig. 23: Image of the female UHF coaxial connector
Because the impedance is not constant, UHF connectors are used in applications where impedance matching is not critical. These types of coaxial connectors are very popular, economical and widely used in low-cost applications such as radios, public address systems, etc.
Sample Specification:
Impedance ————————————— 50 ohms
Frequency range ——————————- 0–2.5 GHz
Working voltage ——————————- 335 VRMS
Dielectric withstand voltage ———– 1000 Volts
VSWR —————————————— 1.25 max. 6GHz
Insulation resistance ————————- 5000 megohms
Summary
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} There are certain parameters that are significant for coaxial connectors such as impedance, VSWR, RF leakage and insertion loss
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} A good coaxial connector should have frequency-independent impedance of 50 ohms or 75 ohms, nearly unity VSWR, minimum RF leakage, minimum insertion and frequency loss higher operational.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} Different types of standard coaxial connectors are available, including SMA, N, TNC, SMC, MCX, BNC, SMB, mini-UHF and UHF
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} Except UHF, all others have frequency independent impedance of 50 ohm or 70 ohm.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} The coaxial connector with the highest operating frequency is the SMA connector with a maximum frequency of 27 GHz and the coaxial connector with the lowest operating frequency is the UHF connector, which can operate below 500 MHz only.
CPC and DIN connectors
CPC CONNECTOR
Circular Plastic Connectors (CPC) were designed and developed during the 1970s. As the name implies, they are mainly made of plastic, except for the metal contacts. They are circular in shape and designed for reliability. The CPC connector is considered an industry standard power and IO connector. They are available in suspended or flanged housings and PCB mountable versions. The CPC connector family includes all types of connectors such as wire-to-wire, wire-to-board, power connectors, IO connectors, and even coaxial connectors.
Figure 24: Image showing different varieties of CPC connectors
The circular geometry allows for a more space-saving method of organizing contacts. Compared to any rectangular connector, the same number of pins can be arranged in the CPC connector in a much smaller space. Wires can be assembled into the CPC using crimping and soldering methods.
Figure 25: Image of the male CPC
Figure 26: Image of the female CPC
CPCs are made from lightweight, stabilized, heat-resistant, self-extinguishing, high-impact thermoplastic materials. Most of them are polarized connectors. They provide easy plugging and unplugging capability. Connector parts including pin, receptacle, etc. can be easily disassembled and thus provide quick repair. Some CPC come with even color codes. CPC can be used to couple signal and power and some of the CPC connectors have a maximum current of 50 amps.
CPC connectors are suitable for applications where size and contact densities are critical, such as industrial, instrumentation, transportation, etc. They are widely used in industrial machinery, factory automation and material handling equipment. They are suitable for railway and transit vehicles and systems, instrumentation and medical equipment. CPC connectors are widely used in all types of communications equipment, networks, data storage, computers and peripherals. The small size and light weight of CPC connectors make them ideal connectors for aerospace and defense equipment and systems.
Sample Specification:
Current rating ———————————- 4 amps
Dielectric withstand voltage ———– 1650 Volts
Contact resistance (milliohms) ————- <5 thousand ohms
Insulation resistance ————————- 5000 megohms
Summary
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} The name CPC stands for Circular Plastic Connector.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} As the name suggests, they are circular and made of plastic except the metal contacts
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} Almost all connector types are available in this connector family
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} The advantage of the circular shape is that it can accommodate a large number of contacts in a small space
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} The advantage of plastic is lightness, durability, easy assembly and repair.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} They can be used to transmit signal and power.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} Connectors are available with a maximum current of 50 amps.
{C}{C}{C}{C}{C}{C} · {C}{C}{C}{C}{C}{C} They are industrial standard IO power connectors and are widely used in all types of devices.
DIN CONNECTOR
The name DIN stands for “Deutsches Institut für Normung”, which is a German standards organization that standardizes this connector. DIN connector is also part of circular connectors. There are different standard connectors in the DIN connector standard. All DIN connectors have the same diameter, but the number of pins differs from the DIN standard. Known DIN standards are DIN41524, DIN41612, DIN43356, DIN41652 etc. The number of pins varies from 3 to 15, maintaining the same external diameter of the connector. Standard DIN connectors are available in pin format as shown in the following image.
Figure 27: Diagram of the different DIN connector standards
DIN connectors use the round snap-fit method. DIN connectors are polarized connectors with a notch in the housing ensuring that the pins will only connect in the correct orientation. It also prevents incompatible connector types from fitting together and damaging their pins. The wires are attached to the pins of the DIN connectors by soldering.
Figure 28: Image of the 7-pin male and female DIN connector
Regardless of the pin numbers, the position of the pins on the DIN connector remains the same. Different DIN connectors with pin numbers are used for different applications.
DIN connectors are used as SYNC and MIDI interface in musical instruments, ham radios, serial ports, PS/2 keyboard and mouse connectors, etc.
Let us look at the different pinouts and other details of DIN connectors used in different applications.
Speaker (2 pin)
Two-pin DIN connectors are used to connect wires to the speaker. The picture of 2 pin male DIN connector for speaker is shown below.
Figure 29: Image showing the pin position of the two-pin DIN connector
The pinout of the 2-pin DIN connector
PIN 1 ——————POSITIVE
PIN 2 ——————NEGATIVE
Microphones (3 pins)
Three-pin DIN connectors are widely used in microphones. They are similar to standard XLR connectors, but are not compatible with them. Three-pin DIN connectors are used on balanced, unbalanced, and dual-impedance microphones. The pin position of the 3-pin DIN connector viewed from the solder side of the plug is shown in the following figure.
Fig. 30: DIN connector diagram
Pin position of the three-pin DIN connector
The pinout of the 3-pin DIN connector for balanced microphone
PIN 1 —————— LIVE
PIN 2 —————— SCREEN
PIN 3 ——————RETURN
The pinout of the 3-pin DIN connector for unbalanced microphone
PIN 1 —————— MONO INPUT
PIN 2 —————— SCREEN
PIN 3 ——————NOT CONNECTED
The pinout of 3-pin DIN connector for dual impedance microphone
PIN 1 —————— MONO HIGH INPUT
PIN 2 —————— SCREEN
PIN 3 —————— MONO LOW INPUT
5-pin DIN
DIN connectors with five pins are used in applications such as stereo microphone, tuners, headphones, etc. The pin position of the 3-pin DIN connector is seen from the solder side of the plug and is shown in the following figure
Fig. 31: 5-pin DIN connector diagram
Pin position of the five-pin DIN connector
The pinout of the 5-pin DIN connector for stereo microphone
PIN 1 —————— LEFT INPUT
PIN 2 —————— SCREEN
PIN 3 ——————NOT CONNECTED
PIN 4 —————— RIGHT INPUT
PIN 5 ——————NOT CONNECTED
The pinout of the 5-pin DIN connector for tuners
PIN 1 —————— LEFT INPUT
PIN 2 —————— SCREEN
PIN 3 —————— LEFT INPUT
PIN 4 —————— RIGHT INPUT
PIN 5 —————— RIGHT INPUT
The pinout of the 5-pin DIN connector for headphones
PIN 1 ——————NOT CONNECTED
PIN 2 —————— LEFT OUTPUT
PIN 3 —————— RIGHT OUTPUT
PIN 4 —————— LEFT OUTPUT
PIN 5 —————— RIGHT OUTPUT
MINI DIN CONNECTOR
MINI DIN and XLR connectors
DIN connectors come in a miniature model called a Mini DIN connector. They are smaller than standard DIN connectors and also the position of the pins varies from the DIN standard.
Figure 32: Image of Male and Female Mini-DIN Connectors
Mini DIN connectors are available with 3- to 9-pin contacts. Mini DIN connectors are used as a standard connector for devices with PS/2 protocol. They are also used as connectors on SVHS video equipment.
4-pin Mini-DIN
Four-pin mini DIN connector is used as cable connector for SVHS video system. The pin position for a four-pin DIN connector viewed from the solder side of the plug is shown in the following figure.
Fig. 33: Diagram of 4-pin Mini-DIN connector
The pin position of a 4-pin SVHS connector
The pinout of 4-pin mini DIN connector for SVHS video system
PIN 1 —————— LUMINANCE GROUND
PIN 2 ——————CHROMINANCE EARTH
PIN 3 —————— LUMINANCE/INTENSITY (Y)
PIN 4 —————-CHROMINANCE/COLOR (C)
PS/2
IBM Personal System 2 (PS/2) is a communications protocol used to interface mouse and keyboard with personal computers. Six-pin mini DIN connectors are defined as standard connectors in this protocol. They are designed to replace the old standard RS232 keyboard and mouse interface method in personal computers. The mini DIN connectors used to connect the mouse and keyboard are electrically identical, but should not be interchanged during connection. The keyboard port can be identified by the purple color and the mouse port can be identified by the green color.
The pin position of a 6-pin female mini DIN connector viewed from the solder side of a plug is shown in the following image.
Fig. 34: PS/2 connector diagram
The pin position of a 6-pin PS/2 connector
The pinout of the 6-pin mini DIN connector for PS/2 devices
PIN 1 ——————DATA
PIN 2 —————— NO CONNECTION
PIN 3 ——————EARTH
PIN 4 ——————VCC
PIN 5 ——————CLOCK
PIN 6 —————— NO CONNECTION
Sample Specification:
Current rating ———————————- 1 amp AC
Voltage Rating ———————————- 100 V
Dielectric withstand voltage ———– 1650 Volts
Contact resistance (milliohms) ————- <5 thousand ohms
Insulation resistance ————————- 5000 megohms
Summary
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}DIN is a circular connector with number of pins ranging from 3 to 15
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}They are polarized connectors
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}DIN connectors are mainly used in audio applications
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}The standard PS/2 connector is a 6-pin mini DIN connector.
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}6-pin mini DIN connectors are used to connect PS/2 keyboard and mouse
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}4-pin mini DIN connectors are used in SVHS video systems
XLR CONNECTOR
XLR is a type of circular connector commonly found in audio and video devices such as microphone, intercom, etc. The XLR connector was designed by James H. Cannon of California. The connector he invented was commercially produced and named in his honor as the Cannon 'X' connector and later a locking version was released. The lock represents the 'L' and the 'R' stands for resilient polychloroprene which was used as the material around the female contacts. XLR connectors are available in 2-pin to 9-pin contact connectors.
Fig. 35: Image of a 3-pin male and female XLR connector
In the image above of the 3-pin XLR connector, you may have noticed the lock on the female connector. This feature in the XLR connector design is a locking mechanism to prevent loose contacts of the male and female connector. Additionally, one of the three pins is longer than the other and is designed so that the longest pin comes into contact before the others. This pin is used to make contact with ground before signal contacts are made. These connectors are very similar in design to the DIN connector, but they are not compatible with each other. XLR connectors are available in cable and chassis mountable models.
The XLR connector is commonly used with all types of electrical connectors, especially in professional audio with balanced audio interconnect, including AES3 digital audio, video, low voltage power supplies, stage lighting equipment, etc.
XLR with different number of pins are used for different applications. Let's take a look at the application and pinout of commonly used XLR connectors.
3-pin XLR
Three-pin XLR connectors are found on almost all types of professional microphones. They are also used as connectors for speaker cables. The pin position of the three-pin male XLR connector is shown below.
Figure 36: 3-Pin XLR Connector Diagram
The pin position for a three-pin male XLR connector
The pinout of the 3-pin XLR microphone connector
PIN 1 ——————EARTH
PIN 2 ——————POSITIVE/BALANCED AUDIO
PIN 3 ——————NEGATIVE/BALANCED CIRCUIT
4-pin XLR
Four-pin XLR connectors are commonly used with talk back headset, unbalanced microphone, analog lighting control, DC power connections, etc. The pin position for the four-pin male XLR connector is shown in the following figure.
Fig. 37: 4-pin XLR connector diagram
The pin position for a four-pin male XLR connector
The pinout of the 4-pin mini DIN connector for a talk balk headset
PIN 1 —————— MIC EARTH
PIN 2 —————— MIC SIGNAL
PIN 3 ——————EARPHONE EARTH
PIN 4 ——————HEADPHONE EARTH
The pinout of the 4-pin mini DIN connector for an analog lighting control device
PIN 1 —————— SCREEN
PIN 2 ——————CLOCK +
PIN 3 ——————ANALOG MULTIPLEX
PIN 4 ——————CLOCK –
Sample Specification:
Current rating ———————————- 15 amps AC
Voltage Rating ———————————- 1400 VRMS
Dielectric withstand voltage ———– 1650 Volts
Contact resistance (milliohms) ————- <3 thousand ohms
Insulation resistance ————————- 1000 megohms
Summary
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}XLR is a type of circular connector commonly used in professional microphones
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}They are similar to DIN but not compatible and have a locking mechanism
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}They are available from 2 to 9 pin contacts
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}XLR 2-pin is used in DC power connectors, 3-pin for microphone, 4-pin for intercom, 5-pin for light control, 6-pin for intercom dual channel, 7 pin microphone with power supply etc.
{C}{C}{C}{C}{C}{C}· {C}{C}{C}{C}{C}{C}Regardless of the applications mentioned above, they are widely used in electrical and electronic devices with user-defined pinouts.
In this tutorial, we learned about circular connectors and saw RF coaxial connector designed for high frequency signal transmission, CPC connector designed for all types of power or signal or both, DIN and XLR which are mainly designed for audio applications.
