Difference between revisions of "Connectors"
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| + | Connector choice is a key part of wiring harness design. Badly chosen or badly assembled connectors can often be the source of electrical issues that are annoying to fix while testing the car, so care should be taken to choose the right connector and the right tools to assemble and disassemble it. | ||
==Housing== | ==Housing== | ||
===Material=== | ===Material=== | ||
| + | Connector housings are made from either plastic or metal. Plastic connectors are usually cheaper and lighter, but are less durable and generally have a lower lifespan than metal connectors. | ||
====Durability==== | ====Durability==== | ||
====Chemical Resistance==== | ====Chemical Resistance==== | ||
| + | Care must be taken when selecting connectors that may come in contact with chemicals (water, fuel, oil, etc) to ensure that this contact will not degrade any part of the connector. | ||
===Weather Sealing=== | ===Weather Sealing=== | ||
| + | Connectors are usually rated with an IP code. Connectors that are open to the elements will need to be rated accordingly. | ||
| + | |||
===Retention=== | ===Retention=== | ||
| + | All connectors feature some sort of retention method. For most connections in a FS car, strong retention methods (locking or tight friction-fit) are required. Only a few applications (e.g. connection between ECU and computer for tuning) may benefit from connectors with weak retention. | ||
====Friction Fit==== | ====Friction Fit==== | ||
| + | Friction fit connectors rely only on the friction between the mating connectors for retention. Friction fit is common in consumer connectors such as USB, but is often unsuitable for the conditions in a FS car. With repeated connect/disconnect cycles, a friction fit connector may wear down, decreasing holding force. | ||
====Locking Tab==== | ====Locking Tab==== | ||
| + | Connectors featuring a locking tab are very common in automotive applications. Some locking tabs can be operated by hand, while others may require a tool to open. A common example of a connector with locking tabs is the Deutsch DTM series. | ||
====Screw Lock==== | ====Screw Lock==== | ||
| + | Screw lock connectors use a threaded screw to retain the connector. While generally resilient, some screw lock connectors can loosen in high vibration environments, especially if not torqued enough. However, over torquing of screw lock connectors can make them difficult to remove. A common example of a screw lock connector is the Binder M9 series. | ||
====Twist Lock==== | ====Twist Lock==== | ||
| + | Twist lock connectors operate similarly to screw lock connectors, however, they feature a mechanism that locks the connector with fewer rotations than a screw lock would require. Twist lock connectors have the benefit of being faster to operate than screw lock connectors, as well as having a hard stop, leaving no doubt as to whether the connector is under or over tightened. A common example of twist lock connector is the Deutsch AS series. | ||
====Cam Lock==== | ====Cam Lock==== | ||
| + | Cam lock connectors use a cam to pull the two mating connectors together. This ensures that all contacts are seated properly, and prevents the connector from coming loose over time. An example of a cam lock connector is the Molex M123 series. | ||
====Push-Pull==== | ====Push-Pull==== | ||
| + | Push-pull connectors require that a sleeve on the connector be pulled back in order to release the locking mechanism. Some connectors require the mechanism to be unlocked when connecting or disconnecting the connector, while others only require this during disconnection. The most common push-pull connectors are made by LEMO. | ||
==Contacts== | ==Contacts== | ||
| Line 20: | Line 32: | ||
====Resistance==== | ====Resistance==== | ||
===Removable=== | ===Removable=== | ||
| + | Some connectors have terminals permanently fixed in the housing (such as most D-subminiature connectors), while others have removable terminals. Removable terminals allow for easier assembly and maintenance, but may increase the size of a connector. Many connectors require specialized tools to remove terminals, and can be damaged by attempting to remove a terminal without the required tool. Many times, however, you can just use a flathead screwdriver - when in doubt, look up tutorials on YouTube. | ||
| + | |||
===Connection Method=== | ===Connection Method=== | ||
| + | Poor connections are a very common cause of failure (and associated time spent troubleshooting). Improper technique is a common cause of this failure. Always make sure students making electrical connections are properly trained on the technique, and understand the importance in redoing a connection if it doesn't look solid. | ||
====Crimp==== | ====Crimp==== | ||
| + | A crimp is a mechanical connection between wire and terminal. The terminal is deformed tightly around the wire conductors, often with additional points secured to the jacket for strain relief. When done properly, this can be an incredibly strong connection - sometimes stronger than the wire itself. For this reason, most professional motorsport wiring harnesses will only use crimped joints. To achieve a reliable crimp, terminals must be properly designed for the wire gauge being used. The correct tools are also necessary; using pliers or a vise will almost always result in a weak connection that is more likely to fail. | ||
====Solder==== | ====Solder==== | ||
| − | + | Soldering is the process of joining two or more parts by melting solder around the connection. When the solder cools, it creates a good electrical connection and a weak mechanical connection. Solder joints are much more brittle than crimped joints, so they are unreliable in high-vibration environments. Solder connections are often found on panel mount connectors in the form of solder cups. Soldering can also be used to reinforce a crimped connection. Always make sure solder is completely wetted out both components in the joint. | |
| + | |||
====Screw Down==== | ====Screw Down==== | ||
| + | Screw terminals use a screw to clamp onto wires. Unlike crimp and solder connections, screw terminals do not permanently or semi-permanently fasten wires, so they are most useful for wiring that won't leave the shop, like for an engine dyno or a test bench. Because they can loosen under vibration, they should not be used on vehicles. | ||
==Types== | ==Types== | ||
===Free Hanging=== | ===Free Hanging=== | ||
| − | This is probably the most common type of connector on an FSAE car. These connect | + | This is probably the most common type of connector on an FSAE car. These connect directly to wires or cables, and can interface either with other free hanging connectors or with panel mount connectors. In FS these will usually need to be weather resistant. The Deutsch DT and DTM series are popular in FS, although many varieties exist. |
| − | |||
===Panel Mount=== | ===Panel Mount=== | ||
| − | Panel mount connectors are used to allow a circuit to interface with | + | Panel mount connectors are often used to allow a circuit inside of a housing, such as a PCB, to interface with external devices. In FSAE these will usually need to be resistant to the weather. They can either be soldered directly to a PCB, or they can be connected to a circuit via wires. |
===PCB Mount=== | ===PCB Mount=== | ||
| − | These are connectors that are soldered to PCBs. They are usually not weather resistant, and are only used inside a housing - either to connect two PCBs, or to connect a PCB to a standalone panel mount connector | + | These are connectors that are soldered to PCBs. They are usually not weather resistant, and are only used inside a housing - either to connect two PCBs, or to connect a PCB to a standalone panel mount connector. |
| − | ===PCB to PCB | + | ===PCB to PCB=== |
PCBs can be directly connected together inside a housing without the use of wires. This is usually done for modularity (so that you can use a PCB for multiple functions), interfacing with a premade part (e.g., a microcontroller), or for packaging reasons. Care needs to be taken so that the solder joints on the connectors are not being overly stressed with the weight of a PCB. | PCBs can be directly connected together inside a housing without the use of wires. This is usually done for modularity (so that you can use a PCB for multiple functions), interfacing with a premade part (e.g., a microcontroller), or for packaging reasons. Care needs to be taken so that the solder joints on the connectors are not being overly stressed with the weight of a PCB. | ||
| − | |||
==OEM Connectors== | ==OEM Connectors== | ||
| − | + | Many off-the-shelf parts either come with a pre-attached connector, or have a connector integral to the part itself. Some parts include a mating connector, while others will require one to be sourced. OEM connectors intended for mass production often have significantly lower connect/disconnect cycle ratings than other connectors. | |
==Standard Connectors== | ==Standard Connectors== | ||
===USB=== | ===USB=== | ||
| − | + | Used for connecting to computers, e.g. for tuning the car or downloading data from a datalogger. | |
===D-Subminiature=== | ===D-Subminiature=== | ||
| + | These are the trapezoid-shaped connectors that you might find on the back of a desktop computer. For racecar purposes, the nine-pin DE-9 connector is often used as a serial port to connect ECUs and motor controllers to a computer. For some mystifying reason, the cavemen that designed the Megasquirt ECU decided to use DB-37 connectors to connect to the main wiring harness, despite the fact that they're not at all rated for regular automotive use. | ||
==RF Connectors== | ==RF Connectors== | ||
| Line 52: | Line 69: | ||
===u.FL=== | ===u.FL=== | ||
===MCX=== | ===MCX=== | ||
| − | |||
==Considerations== | ==Considerations== | ||
===Density=== | ===Density=== | ||
| + | Connectors can vary greatly in how close together the pins are. A connector with a higher density will usually be lighter and easier to package, but they can be more expensive and harder to assemble. | ||
===Connect/Disconnect Cycle Rating=== | ===Connect/Disconnect Cycle Rating=== | ||
| + | As connectors are connected and disconnected, the contacts and components will deteriorate. The cycle rating is how many times this can happen while still meeting the specifications for minimum resistance and pull force. Many connectors (like board to board connectors) are only rated to tens of cycles, while some (like USB connectors) are rated for thousands of insertions. | ||
| + | |||
| + | |||
[[Category:Electronics]] | [[Category:Electronics]] | ||
Latest revision as of 03:02, 22 May 2021
Connector choice is a key part of wiring harness design. Badly chosen or badly assembled connectors can often be the source of electrical issues that are annoying to fix while testing the car, so care should be taken to choose the right connector and the right tools to assemble and disassemble it.
Contents
Housing
Material
Connector housings are made from either plastic or metal. Plastic connectors are usually cheaper and lighter, but are less durable and generally have a lower lifespan than metal connectors.
Durability
Chemical Resistance
Care must be taken when selecting connectors that may come in contact with chemicals (water, fuel, oil, etc) to ensure that this contact will not degrade any part of the connector.
Weather Sealing
Connectors are usually rated with an IP code. Connectors that are open to the elements will need to be rated accordingly.
Retention
All connectors feature some sort of retention method. For most connections in a FS car, strong retention methods (locking or tight friction-fit) are required. Only a few applications (e.g. connection between ECU and computer for tuning) may benefit from connectors with weak retention.
Friction Fit
Friction fit connectors rely only on the friction between the mating connectors for retention. Friction fit is common in consumer connectors such as USB, but is often unsuitable for the conditions in a FS car. With repeated connect/disconnect cycles, a friction fit connector may wear down, decreasing holding force.
Locking Tab
Connectors featuring a locking tab are very common in automotive applications. Some locking tabs can be operated by hand, while others may require a tool to open. A common example of a connector with locking tabs is the Deutsch DTM series.
Screw Lock
Screw lock connectors use a threaded screw to retain the connector. While generally resilient, some screw lock connectors can loosen in high vibration environments, especially if not torqued enough. However, over torquing of screw lock connectors can make them difficult to remove. A common example of a screw lock connector is the Binder M9 series.
Twist Lock
Twist lock connectors operate similarly to screw lock connectors, however, they feature a mechanism that locks the connector with fewer rotations than a screw lock would require. Twist lock connectors have the benefit of being faster to operate than screw lock connectors, as well as having a hard stop, leaving no doubt as to whether the connector is under or over tightened. A common example of twist lock connector is the Deutsch AS series.
Cam Lock
Cam lock connectors use a cam to pull the two mating connectors together. This ensures that all contacts are seated properly, and prevents the connector from coming loose over time. An example of a cam lock connector is the Molex M123 series.
Push-Pull
Push-pull connectors require that a sleeve on the connector be pulled back in order to release the locking mechanism. Some connectors require the mechanism to be unlocked when connecting or disconnecting the connector, while others only require this during disconnection. The most common push-pull connectors are made by LEMO.
Contacts
Material
Corrosion Resistance
Wear Characteristics
Sizing
Ampacity
Resistance
Removable
Some connectors have terminals permanently fixed in the housing (such as most D-subminiature connectors), while others have removable terminals. Removable terminals allow for easier assembly and maintenance, but may increase the size of a connector. Many connectors require specialized tools to remove terminals, and can be damaged by attempting to remove a terminal without the required tool. Many times, however, you can just use a flathead screwdriver - when in doubt, look up tutorials on YouTube.
Connection Method
Poor connections are a very common cause of failure (and associated time spent troubleshooting). Improper technique is a common cause of this failure. Always make sure students making electrical connections are properly trained on the technique, and understand the importance in redoing a connection if it doesn't look solid.
Crimp
A crimp is a mechanical connection between wire and terminal. The terminal is deformed tightly around the wire conductors, often with additional points secured to the jacket for strain relief. When done properly, this can be an incredibly strong connection - sometimes stronger than the wire itself. For this reason, most professional motorsport wiring harnesses will only use crimped joints. To achieve a reliable crimp, terminals must be properly designed for the wire gauge being used. The correct tools are also necessary; using pliers or a vise will almost always result in a weak connection that is more likely to fail.
Solder
Soldering is the process of joining two or more parts by melting solder around the connection. When the solder cools, it creates a good electrical connection and a weak mechanical connection. Solder joints are much more brittle than crimped joints, so they are unreliable in high-vibration environments. Solder connections are often found on panel mount connectors in the form of solder cups. Soldering can also be used to reinforce a crimped connection. Always make sure solder is completely wetted out both components in the joint.
Screw Down
Screw terminals use a screw to clamp onto wires. Unlike crimp and solder connections, screw terminals do not permanently or semi-permanently fasten wires, so they are most useful for wiring that won't leave the shop, like for an engine dyno or a test bench. Because they can loosen under vibration, they should not be used on vehicles.
Types
Free Hanging
This is probably the most common type of connector on an FSAE car. These connect directly to wires or cables, and can interface either with other free hanging connectors or with panel mount connectors. In FS these will usually need to be weather resistant. The Deutsch DT and DTM series are popular in FS, although many varieties exist.
Panel Mount
Panel mount connectors are often used to allow a circuit inside of a housing, such as a PCB, to interface with external devices. In FSAE these will usually need to be resistant to the weather. They can either be soldered directly to a PCB, or they can be connected to a circuit via wires.
PCB Mount
These are connectors that are soldered to PCBs. They are usually not weather resistant, and are only used inside a housing - either to connect two PCBs, or to connect a PCB to a standalone panel mount connector.
PCB to PCB
PCBs can be directly connected together inside a housing without the use of wires. This is usually done for modularity (so that you can use a PCB for multiple functions), interfacing with a premade part (e.g., a microcontroller), or for packaging reasons. Care needs to be taken so that the solder joints on the connectors are not being overly stressed with the weight of a PCB.
OEM Connectors
Many off-the-shelf parts either come with a pre-attached connector, or have a connector integral to the part itself. Some parts include a mating connector, while others will require one to be sourced. OEM connectors intended for mass production often have significantly lower connect/disconnect cycle ratings than other connectors.
Standard Connectors
USB
Used for connecting to computers, e.g. for tuning the car or downloading data from a datalogger.
D-Subminiature
These are the trapezoid-shaped connectors that you might find on the back of a desktop computer. For racecar purposes, the nine-pin DE-9 connector is often used as a serial port to connect ECUs and motor controllers to a computer. For some mystifying reason, the cavemen that designed the Megasquirt ECU decided to use DB-37 connectors to connect to the main wiring harness, despite the fact that they're not at all rated for regular automotive use.
RF Connectors
BNC
SMA
TNC
N Connector
u.FL
MCX
Considerations
Density
Connectors can vary greatly in how close together the pins are. A connector with a higher density will usually be lighter and easier to package, but they can be more expensive and harder to assemble.
Connect/Disconnect Cycle Rating
As connectors are connected and disconnected, the contacts and components will deteriorate. The cycle rating is how many times this can happen while still meeting the specifications for minimum resistance and pull force. Many connectors (like board to board connectors) are only rated to tens of cycles, while some (like USB connectors) are rated for thousands of insertions.
