Features And Functions Of Rotary Switches

A rotary switch is one of the most common types of devices found in equipments which can be operated in more than one mode. These switches include complex functionalities in comparison to ordinary switches and devices. These switches are used in equipments to perform a variety of tasks which can seldom be performed by an ordinary switch.

In the earlier days, the rotary switch was used to change the channels instead of a remote control. These switches are designed to handle different functions at the same time. Most of the ordinary switches are capable of performing only one function where as these devices can be used to perform multiple tasks in the same equipment.

The rotary switch includes a spindle which is connected to a contact arm. There are a series of pins or terminals at the base of the switch. Each and every pin on the switch is assigned to a different application such as high, low, reverse, forward and so forth. When the dial of the switch is turned, the contact arm connects to one of the terminals. When the connection is made, the circuit closes and the operation begins.

There are many benefits associated with the use of these switches. It is quite efficient as it simplifies the job processes. It reduces the cost as it enables different functions with a single switch.

In comparison to the traditional pole rotary switch, these switches are connected to the terminals by soldering them or rather with the use of slide on connectors.

Select a discreet position: The rotary switch can be used to select a discreet position by simply turning the knob. Therefore it is also known as selector switches. The rotating shaft in the device connects to a particular terminal. It can be connected and disconnected from other terminals.

Used for various purposes: Although today it find its application in various fields such as heater fan, head lights, wind shield washers, volt-ohm meters, household appliances such as blenders and food processors, it was first used to change the channels in early television sets.

Variations: There are variations in the type of rotary switches according to its operational functions. Some of these switches are operated by electrical motors where as some of these switches are operated manually. Another variety is the timer motor switch which is used for washers. The cycle selector switches in cloth washers include both the manual and the electrical motors.

Movements of the switch: The user can easily rotate the switch spindle to different directions to perform different functions. These switches can be used to control medical equipments, computers, communication devices and so forth.

Sensor and detent mechanism: It has a sensory system and a detent mechanism which determines the number of possible switch positions.

There are different types of rotary switches available in the stores today. Most of these switches are made available in the online stores too. It is available on the basis of pin arrangements and some of the most important varieties include the Double Pole- 6 way, the Single Pole-12 way, Quad Pole-3 way and the Triple Pole-4 way.

Dimmer Switch Selection – So Many Choices

While having dinner at a friend’s home the other night something hit me. The evening was great; good food, fabulous hosts, and an overall perfect time. But what finally struck me was the ambient lighting in the dining room. Sure, I had seen dimmed lighting before, but at this moment I came to appreciate what a subtle change in lighting can do for the mood of an evening. So what if you too would like to install a dimmer switch in your home? This article will help you select what style and features to look for in a dimmer. Our previous article addresses dimmer installation, and the next installment sums it all up with easy installation for the right application.

We will cover the choices available here for incandescent or halogen bulbs (most common). You need a specialized dimmer switch for fans, compact fluorescent bulbs, or the tube style fluorescent bulbs and in a future article we can explain those choices. But never use a regular dimmer switch for these applications.

The first step is selecting the style and type of dimmer switch that fits your home. Color choices are similar with white, ivory, or brown being the most common colors. Usually you want to also match the style of switches you already have. Some homes have the traditional small toggle switch that sticks out. Others have the more modern Decora style switches that are large rectangles almost flush with the switch plate that toggle back and forth from finger pressure at either end. These styles are interchangeable given you get the right switch plate cover, so it is a matter of personal taste and typically choosing to match the rest of the home.

In the traditional style, dimmers come in round buttons that you twist to dim the lights and push to toggle the lights on and off. Another style has a regular on off switch but at the side is a small little slide that can be moved to set the light level. Both of these types are nice in that you can set the lights at a level you like normally and then just flip the lights on and off and not have to adjust the dimming each time. One other style is available in this type of traditional switch that looks exactly like a regular switch except it doesn’t snap on and off. When you go to move the switch to turn the lights on, instead of clicking on and off it moves smoothly between the two going from full on to full off and anything in between. My preference with these though is the combination switch and sliders as being most convenient to use.

The Decora style switches have even more options. The simplest have a vertical slider that goes up and down similar to the continuous range from the on to off type described above. Next is my economical favorite which looks like a regular switch but has the added slider on the side. With the help of some additional electronics inside the box, the choices can get even fancier. One just uses the touch of your finger and continuously dims or brightens until you remove your finger. Others you push and hold down either end of the switch and a series of indicator lights on the side will show the power level. Another option that can be handy is a backlight on the switch so it glows orange when the switch is off. This becomes useful when using a dimmer switch to control a night light in the bathroom. You can control how bright the light is and if someone forgot to turn it on before going to bed you can at least find the switch!

Make sure you know how large an electrical load the switch will be connected to and then look at the rating on the dimmer switch you are considering. You might need to get a high watt rated switch. For example if a switch is rated for 350 Watts, you can have a chandelier that has 5 60 Watt light bulbs (5×60=300) but 5 75 Watt light bulbs would require a higher rated switch.

The only other choice you need to be aware of is whether you need a two-way, three-way, or in rare cases a four-way switch. Two-way are the most common and that is when only one switch controls the light. Three-way switches are needed when two switches can turn the light off an on, typically seen when there is a switch for the light at two entrances into the room. Four-way switches are used for a very large room that has three or more switches controlling the same light. If you want to know how to connect up a three-way or four-way switch, you can read our previous article on that topic.

Now you are practically an expert on dimmer switch styles. If simple is what you have in mind, the local hardware store has you covered. I have also had great luck buying dimmer switches online. They tend to offer better pricing and more selection of color and style, and good online stores can help you with the installation over the phone.

Hubs, Switches And Routers – What’s The Difference?

The backbone of a computer network uses 3 types of devices to interconnect computers — hubs, switches and routers. Each is important and serves a different role in facilitating communication between networked computers. From the outside these devices may look similar — small, metal boxes with multiple connectors or ports where ethernet cables are attached (routers may also expose other types of connectors). The terms ‘hub’, ‘switch’, and ‘router’ are often used interchangeably and misused — in fact, the devices are quite different. Hubs are used to simply interconnect individual computers. Switches do the same (but more efficiently). However, routers interconnect different networks (as opposed to individual machines).

Network Hub:

Compared to switches and routers, hubs are the least expensive, simplest device on the network. All data that enters one port of the hub is sent out all the other ports. Hence, all computers connected to the same hub see each other’s network communications. The hub doesn’t pay any attention to the transmitted data, it simply passes it along to its other ports. A hub’s value lies in the fact it is inexpensive and offers a quick and easy way to connect computers in a small network.

Network Switch:

The job of a switch is similar to a hub’s — but it does it more efficiently. Each packet of data (ethernet frame) that is transmitted on the network has a source and destination MAC address. A switch has the ability to remember the address of each computer attached to its ports and will act as a traffic cop — only passing transmitted data to the destination machine and not all the others. This can have a significant positive affect on network performance because it eliminates unnecessary transmissions and frees-up network bandwidth. A switch can be thought of as the central component of a single network. It is used to interconnect devices on the network and to deliver layer 2 (OSI model) frames. A switch differs from a hub in that it does not retransmit frames to all other devices — rather, a switch makes a direct link between the transmitting and receiving devices.

Network Router:

Compared to switches, routers are slow and relatively expensive. A router is an intelligent device that interconnects two or more networks for the purpose of delivering layer 3 (OSI model) packets. Since there may be more than one possible path, a router takes into account multiple criteria when determining which path to send the data packets. The fact that switches and routers operate at different layers of the OSI model indicates they rely on different information (contained in the frames or packets) to send data from a source to a destination.

An important difference between switched and routed networks is switched networks do not block broadcasts. As a result, switches can be overwhelmed by broadcast storms. Routers block LAN broadcasts, so a broadcast storm only affects the broadcast domain from which it originated. Since routers block broadcasts, they also provide a higher level of security than switches.

Analogy

Here’s an analogy to help explain the difference between a router and switch — a corporation’s mail room. When an employee sends a letter it may (a) be delivered to its final destination by the company’s internal mail delivery system or, (b) taken to the local Post Office (if the recipient resides outside the company). A switch represents the corporation’s mail room, and a router the local Post Office.

A switch does not look inside the mail or examine the type of mail being delivered. The only logic behind a switch is a table of MAC addresses (one for each computer on the network) and which port a destination MAC is connected. That is, the switch stores a table of company employees and their office numbers and is responsible for delivering internal mail directly to employees. So, if mail arrives at the switch that is destined for an employee then a switch knows how to deliver it. A router, on the other hand, is responsible for delivering mail destined for individuals outside the company. In addition, routers can look inside the mail and delivery rules can be applied based on the mail’s contents. This feature allows routers to play an important role in network security.

How a Switch Operates:

Switches are essentially multi-port bridges. They were designed to reduce the size of collision domains. In addition to faster CPUs and memory, two other technological advances made switches possible — Content Addressable Memory (CAM) and application-specific integrated circuits (ASIC). CAM is memory that works backward compared to conventional memory — that is, given a data value the memory returns the associated address. This allows a switch to directly find the port associated with a MAC address (the data value). An ASIC is a device that can be programmed to perform functions at logic speeds in hardware. The use of CAM and ASIC technologies greatly reduced the delays caused by software processing and enabled a switch to keep pace with the demands of high data rates in Ethernet networks.

Switches can operate in one of three modes — store-and-forward, cut-through and fragment-free. The trade-offs are performance versus reliability. In store-and-forward switching the switch reads the entire frame and checks for errors. In cut-through switching the switch reads the beginning of the frame up through the destination MAC address. In fragment-free switching the first 64 bytes of a frame are read — enough to determine whether or not it is a collision fragment (which account for the majority of frame errors).

The Layer 2 switch builds its forwarding table using MAC addresses. When a host has data for a non-local IP address, it sends the frame to the closest router (also known as its default gateway). The host uses the MAC address of the router as the destination MAC address.

How a Router Operates:

Just as a switch keeps a table of known MAC addresses, a router keeps a table of IP addresses known as a routing table. An important function of a router is to maintain these tables and make sure other routers are notified of changes in the network topology. This function is performed using routing protocols to communicate with other routers. When packets arrive at a router’s interface it applies various criteria and protocols to determine the best path on which to transmit the packet to its next destination.

A router can be programmed to apply sophisticated rules based on the contents of the data packets that it sees. For example, routers can be programmed to act as hardware firewalls, can implement network address translation (NAT) and provide DHCP services to the network.

Because of their built-in intelligence, routers are generally considered the most complex devices on a network. In addition to directing packet traffic, routers can be configured to monitor network traffic, adapt to changes in the network that they detect dynamically, and protect networks by filtering packets and determining which packets will be blocked or allowed through.