Archives For Components

External Power Supplies

eiodotcom —  October 3, 2012 — Leave a comment

Today’s EIO post is on external power supplies.



External Power Supplies 101


External power supplies are devices that convert ac power from a wall outlet into lower voltage dc or ac power to be used directly by electronic circuits. External power supplies come in a separate physical enclosure than the end-use product, and usually provide power to the device directly through a separate cord and plug. External power supplies are used to power a variety of electronic devices, including: laptop computers, printers, cordless phones, cell phones, etc.


External power supplies are used both with equipment with no other source of power, and with battery-powered equipment, where the supply both charges the battery and powers the equipment when plugged in. One of the benefits of using an external, rather than internal power supply is it increases the portability of a device, by avoiding the need of internal power components. Use of an external power supply allows portability of battery-powered equipment without the added bulk of internal power components and makes it unnecessary to produce equipment for use only with a specified power source.


Benefits of Using an External Power Supply

Safety — External power adapters can free product designers from worrying about some safety issues. Much of this style of equipment uses only voltages low enough not to be a safety hazard internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used (usually via a power connector, often of coaxial type), the equipment need not be designed with concern for hazardous voltages inside the enclosure. This is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts.

Heat reduction — Heat reduces reliability and longevity of electronic components, and can cause sensitive circuits to become inaccurate or malfunction. A separate power supply removes a source of heat from the apparatus.

Electrical noise reduction — Because radiated electrical noise falls off with the square of the distance, it is to the manufacturer’s advantage to convert potentially noisy AC line power or automotive power to “clean”, filtered DC in an external adapter, at a safe distance from noise-sensitive circuitry.

Weight and size reduction — When most power adapters featured simple mains-frequency transformer-based designs, they were quite heavy and large, and added considerably to the weight and bulk of devices designed to be lightweight. Even modern power supplies are relatively heavy compared to other circuitry. Removing power components from equipment powered by rechargeable batteries reduces the weight and size which must be carried, though use of other rechargeable batteries like sealed lead-acid batteries can questionably put more weight on the equipment.

Ease of replacement — Power supplies are more prone to failure than other circuitry due to their exposure to power spikes and their internal generation of waste heat. External power supplies can be replaced quickly by a user without the need to have the powered device repaired.

Configuration versatility — Externally powered electronic products can be used with different power sources as needed (e.g. 120VAC, 240VAC, 12VDC, or external battery pack), for convenient use in the field, or when traveling.

Some of Our Products  (To see all power supply products, click here)





Brand Velleman
Supply Voltage 100 ~ 240V AC
Power 36W
Efficiency >=70%
Selectable Outputs 5 to 24V DC in steps of 1V (from 4.3 to 1.5A)
Output Plugs 2.5mm mono, 3.5mm mono, 1.0×3.0mm, 1.35×3.5mm, 1.7×4.0mm, 2.1×5.0mm, 2.5×5.5mm, 1.5×5.5mm
Dimensions 3.5″ x 1.8″ x 1.2″
  • with 8 detachable DC plugs
  • for notebook computers & personal digital electronic devices
  • stabilized output, low ripple & interference
  • short-circuit & overload protection
  • high efficiency & low energy consumption









This switch mode regulated power supply wall adapter comes with 4 input plugs to operate around the world. Includes input power plugs for the US, UK, Europe, Taiwan, and China! Additionally, choose from 7 different DC output connectors. Finally, a switching power supply adapter with a user selectable output plug size and polarity!

Get rid of those bulky power-hungry heat-producing linear power adapters. These switching power adaptors are state-of-the-art switch mode power supplies featuring major advantages such as:
– cooler running
– stabilized (regulated) output
– short-circuit and overload protection
– compact design
– very low idling power consumption
– multiple (selectable) voltage outputs
– user configurable output connector polarity: center (+)  or  center (-)
– world wide AC input voltage range


  • 4 AC input power plug configurations included (user selectable)
    • AC plugs to fit in US, UK, Europe, Taiwan and China
  • compact switch mode regulated power supply design is light-weight and efficient


  • AC input supply voltage: 100 ~ 240V AC, 50/60 Hz
  • output power: 24.0 watts max.
  • efficiency: > = 70%
  • user selectable output voltages:
    • 3V,  4.5V,  6V, 7.5V, 9V, and 12V DC
  • output current: 2,000ma (2 amps) maximum current consumption
  • 7 DC output connector plugs included (user selectable)
    • 2.5mm (male)
    • 3.5mm (male)
    • 2.35×0.75mm (female)
    • 3.5×1.35mm (female)
    • 4.0×1.7mm (female)
    • 5.0×2.1mm (female)
    • 5.5×2.5mm (female)
  • power supply dimensions: 4.6″ x 2.4″ x 3.3″  (11.6cm x 6.1cm x 8.3cm)







Brand Velleman
Supply Voltage 100 ~ 230V AC ± 15%
Power 10W
Efficiency > 80%
Output Voltages 3, 4.5, 6, 7.5, 9, 12V DC
Output Current 800mA (regulated) / 1.5A max.
Plugs 2.5mm mono, 3.5mm mono, 1.0×3.0mm, 1.35×3.5mm, 1.7×4.0mm, 2.1×5.0mm, 2.5×5.5mm, 1.5×5.5mm
Dimensions 2.6″ x 1.1″ x 2.9″
Weight 3.0 oz
Features Get rid of those bulky power-hungry heat-producing mains adapters.
These adaptors use state-of-the-art switching power supplies and feature some major advantages such as:
– cooler running
– stabilized output
– short-circuit and overload protection
– compact design
– very low idling consumption

Today’s EIO post is on car electronics and the different products related to rear view cameras for automobiles.

What are Backup Cameras:

A backup camera is a special type of video camera that is produced specifically for the purpose of being attached to the rear of a vehicle to aid in backing up. Backup cameras are alternatively known as ‘reversing cameras’ or ‘rear view cameras’.

The design of a backup camera is distinct from other cameras in that the image is horizontally flipped so that the output is a mirror image. This is necessary because the camera and the driver face opposite directions, and without it, the camera’s right would be on the driver’s left and vice versa. A mirrored image makes the orientation of the display consistent with the physical mirrors installed on the vehicle. A backup camera typically sports a wide-angle or fisheye lens. While such a lens spoils the camera’s ability to see faraway objects, it allows the camera to see an uninterrupted horizontal path from one rear corner to the other. The camera is typically pointed on a downward angle, to view potential obstacles on the ground as well as the position of approaching walls and docks, rather than straight back.


Pyle PLCM19 Low Lux Rear Camera Black Chrome Metal Lisence Plate Frame


Low Lux Rear Camera
Black Chrome Metal
License Plate Frame


Brand Pyle
Model PLCM19
Type Back up Camera & Rear View Mirrors w/ Monitors
  • 420 TVL Horizontal Resolution
  • Waterproof Rating : IP67
  • Sensor Image: Color CMD Sensor
  • Low Light Capable
  • 17 Foot Male to Male RCA Video Cable
  • TV System: PAL/NTSC
  • Effective Pixels: 512 x 492
  • Resolution (TV Lines) : 420
  • Resolution (TV Lines) : 420
  • Video Output: 1.0V pp-77Ohm
  • Lens Angle: MAX 170°
  • Power Supply: DC 12V
  • Current Consuption (mA): 200mA
  • Dimension: 312 x 162 mm
  • Operating Temperature (Deg
  • C): -20 – +75 (RH95%MAX.)
  • Storage Temperature (Deg
  • C): -40 – +85 (RH95%MAX)
  • Sold as : Unit


PYLE PLCM7300BT 7″ Mirror Monitor W/ Rearview Night Vision Camera Built-In Bluetooth


7”TFT Mirror Monitor
Rear-View Night Vision Camera
Built-In Bluetooth


Brand PYLE
Model PLCM7300BT
Type Rear View System
Dimensions Screen Dimensions: 10.19″ x 4.25″ x 1.81″

Camera Dimensions: 8.46″ x 1.29″ x 1.37″

Features 7″ TFT (16:9) Wide Screen

Universal Clip On Existing Mirrors

Wireless Remote Control

Resolution: 480 x RGB x 234

Contrast Ratio: 400 CD/M2

Viewing Angle: U/D90° L/R120°

Power Consumption: 6W

Auto Switch PAL/NTSC

Dual Video Input(DVD/CAMERA/GAME)

Rearview Night Vision Camera

Built-In Bluetooth System

Display In-coming Calls

License Plate Mount

Anti Glare Mirror


PYLE PLCM24IR Universal Mount Rear View Backup Camera


Universal Mount Rear View Backup Camera
Brand Pyle
Model PLCM24IR
Type Rear View Camera
Image Sensor 1/3″ Color CMD
Pixels 580 x 540
Resolution 420 TV Lines
Illumination 1.0 LUX (Min.)
View Angle 170°
Output Level 1.0 Vpp-75 Ohm
Power Requirement DC 12V
Dimensions 0.67″ x 0.67″ x 0.9″
Features Water Proof 1/3″ Color CMD

17 Foot Male to Male RCA Video Cable

IP Rating: 68

Auto Image Adjustment

PYLE PLCM38FRV Universal Rear View Backup Color Camera


Universal Mount Optional Front View & Rear View Backup
Color CMD
Distance Scale Line Camera


Brand Pyle
Image Sensor 1.3″ Color DVD
Pixels 580 x 540
Resolution 8 420 TV Lines
Illumination 0.5 LUX (Min.)
View Angle 170°
Color System PAL / NTSC
Output Level 1.0 Vpp-75 Ohm
Power Requirement DC 12V
Dimensions 3.18″ x 2.95″ x 2.17″
Features Water Proof Front & Rear View Camera

17 Foot Male To Male RCA Video Cable

Ip rating: 68

Auto Image Adjustment

LED Light For Night vision

Distance Scale Line


Inductors 101

eiodotcom —  June 2, 2012 — Leave a comment

Today’s Eio post covers inductors.

What is it?

Different types of inductors

The most basic forms of inductors are tightly wrapped coils of wire, which are used in electronic circuits. Due to the magnetic properties of a coil, inductors are able to store energy in their magnetic fields. In other types of inductors, the coil is wrapped around certain types of core material (most often iron) to increase the inductance of the wire.

If you’d like to understand the process of inductance in more easy-to-understand detail, visit the inductors page on

What is it used for?

Inductors are commonly used in radio frequency devices. They are frequency-specific components, so they help produce or eliminate specific frequencies in a signal. Inductors are make up transformers, which are fundamental components of any electric utility power grid. They are also used as the energy storage device in some switched-mode power supplies.

So check out some of Eio’s popular inductor products:

Toko Choke Coil Shielded 22uH 20% 1KHz 2.21A RDL Inductor

TRENDnet TC-TP1 Net Probe (Amplified Inductor and Tone Probe)

See also:

DC Motors 101

eiodotcom —  May 26, 2012 — 3 Comments

Today’s Eio post is on DC Motors.

What is it?

A DC motor is a motor that runs on direct current (DC) electricity.DC motors use the electricity and a magnetic field to produce torque (the force which causes the motor to spin). WiseGeek summarizes the concept of how a DC motor works like this:

At its most simple, a DC motor requires two magnets of opposite polarity and an electric coil, which acts as an electromagnet. The repellent and attractive electromagnetic forces of the magnets provide the torque that causes the DC motor to turn.

If you’ve ever played with magnets, you know that they are polarized, with a positive and a negative side. The attraction between opposite poles and the repulsion of similar poles can easily be felt, even with relatively weak magnets. A DC motor uses these properties to convert electricity into motion. As the magnets within the DC motor attract and repel one another, the motor turns.

What is it used for?

DC motors are in just about everywhere! Howstuffworks offers a neat exercise: walk through your house and you’ll find close to 100 DC motors present! As a breakdown, motors are in:

  • the bathroom (hairdryer, electric toothbrush)
  • the kitchen (refrigerator, sink’s dispose-all)
  • the utility room (washer, dryer)
  • the car (power windows, windshield wipers)

So if you’re interested in replacing a DC motor or starting your own DIY project, check out Eio‘s catalog.


Yokogawa RM-H6A6S-U Reversable Motor

See also:

Relays 101

eiodotcom —  May 23, 2012 — 3 Comments

Today’s Eio post is on relays.

What is it?

A relay is an electromechanical device that uses an electromagnet to open or close a switch. In other words, Chet Walters says “a relay works this way: Your switch ‘turns on’ the relay.  The relay ‘turns on’ your accessory. A relay draws very little current through your switch which protects your switch from burnout.  The ‘turned on’ relay can switch a much larger current and not burn out.”

How a relay works. says there are four parts in every relay: an electromagnet, an armature, a spring, and a set of electrical contacts. In essence, when you turn the switch on, it sends electrical current through the circuit and powers the electromagnet. The electromagnet then attracts the armature which acts as a second circuit and completes the circuit so that the light (or electrical appliance) turns on. When you turn the switch off, the armature retracts and makes the circuit incomplete, so that the light (or appliance) turns dark.

What are Relays Used for?

Relays have many uses. Their primary functions include separating AC and DC currents and multiple switching functions, such as delay or signal conditions.

They are used in many electronic applications, such as domestic appliances, air conditioning and heating, lighting and building control, and automotive electrics.

So check out some of Eio’s popular relays:

Velleman Relay Card with LED light switch indicator

Panasonic Power Relay

Velleman Multifunction Relay Switch (includes timers, switching, flashing, interval, random switching)

See also:

Continuing on in our emphasis at making electronics easily accesible and understandable, Eio presents a non-technical explanation of resistors.

What is a resistor? What does it do?

American resistor symbol

A resistor is an electronic component whose purpose is to “resist” (oppose) the flow of electrical current. Resistors are most commonly used in electronic circuits, which are devices that allow electric currents to flow. says, “because resistance is an essential element of nearly every electronic circuit, you’ll use resistors in just about every circuit that you build.”

Resistance is measured in ohms (Ω), where the relationship between current, volts, and resistance is represented by ohm’s law. PlaywithArduino states that to understand resistance, one must understand voltage and current, as defined here:

  • voltage (V) is the measure of the strength electric charges are attracted between the two points
  • current (I) is the measure of how many electric charges are moving per unit time between the two points.

Resistors dissipate power by resisting or limiting the voltage and thus bring down the electricity flow. If a resistor dissipates too much power, it will burn up. Be sure to check the amount of resistance it can handle, often denoted by 1/8, 1/4, 1/2, 1, and 2 watts.

What are resistors used for?

Xicon 3.3 Ohms 1/4 Watt Carbon Film Resistor

Resistors, according to, are used in the following areas:

  • Plate resistor (usually a load)
  • Cathode resistor (usually for biasing, sometimes a load)
  • Grid resistor (to limit ultra HF response)
  • Screen resistor (to limit screen current)
  • Bias resistor (to keep the grid at a constant DC level, often zero or ground)
  • Voltage divider (to cut down the signal level, particularly in high gain amps)
  • Part of an RC low-pass filter (to both lower the voltage and reduce the ripple in the “downstream” parts of a power supply)

So visit our Eio site for all your resistor needs!


See also:

Here at Eio, we want to make electronics accessible to all people, experts and beginners alike. We resist assuming our customers will possess or pursue a thorough understanding of electronics, which requires us to provide explanations of electronic equipment in easy to understand, non-technical language. So today’s post is an effort to give a non-technical explanation of capacitors.

What is a capacitor? What does it do?

According to Wikipedia, a capacitor is an electrical component used to store energy by means of an electrostatic field. Capacitors have at least two electrical conductors separated by an insulator, the dielectric (see Fig. 1).

Fig. 1 Picture of a capacitor

The conductors are connected to terminals so that voltage can be applied across the conductors.

When voltage is applied across the conductors, an electrostatic field develops along the insulator resulting in a positive charge to collect on one terminal and a negative charge on the other. The electrostatic field is what actually stores the energy by the pulling and pushing forces of the positive and negative charges, similar to how charges within protons, neutrons, and electrons hold atoms together.

If you’d like more technical and detailed information, such as the mathmatical formula for how capacitance works, please go here or here.

What are capacitors used for?

Capacitors are used in the following areas:

  • Energy sotrage – they can store electric energy and be used like temporary batteries.
  • Pulsed power and weapons – they are used to supply huge pulses of current, such as detonators.
  • Power conditioning – are used as reserves for some power sources.
  • Suppression and coupling – used as noise filters and snubbers.

    Makezine’s capacitor bank and charger

  • Motor starters – starting capacitors are capable of starting rotational motions in many motors.
  • Signal processing – used for tuned circuits to read particular frequencies.
  • Sensing – senses changes in the capacitance structure.

DIY Projects

If you’re an inventor at heart, here are some links to fantastic DIY capacitor projects.

Check out a popular capacitor product at Eio:


See also: