Vision from Veronica Zoeckler on Vimeo. How do the parts of the eye manipulate light to produce vision? Vision as it relates to anatomy and physiology….
The output from an unregulated power supply unit or a DC voltage source from a wall adapter contains many ripples also known as noise. these ripples are inherent in the AC voltage signal and sometimes come from spike or electromagnetic interference and no amount of filtering will totally get rid of these noise.
The ripple is not good for many electronic devices because it affects the function of sensitive electronic components such as transistor and integrated circuits, the problem is worse for digital circuits. For normal analog application, when the load draw from the supply, the ripple is more severe results in reduce working voltage, therefore the equipment will not deliver as expected and probably damage it.
To secure a well filtered and well regulated DC voltage for devices to function as required, we have the fixed and variable voltage regulators; the fixed varieties include 78xx and 79xx for positive and negative regulators respectively. The adjustable types include LM317 and LM337 for positive and negative variable regulators respectively. Check the pin-outs for these components before insert them in circuit. Simply add any of them to a filtered rectifier circuit or AC wall adapter and you are set.
The voltage from the regulator is straight and devoid of damaging ripples. You need one for your next electronic project design and construction.
Often what you required to run an equipment or device is a well-regulated source of DC power and in its simplest form it is known as a battery eliminator. However, for some application the simple battery eliminator is less desirable so you need a well-regulated when running equipment from batteries as well as from a…
An oscillator is used to generate a repetitive and periodic waveform of desired shape, frequency, and amplitude and you will find one in practically every electronic apparatus. It is either used to drive a load or to drive other circuits. Listed below are characteristic shapes of some oscillators.
Some signals are combined or mixed together to alter the shape and characteristics output to achieved a particular purpose.
Different types of oscillators find useful application in the following areas but not limited to these:
- Signal broadcast by radio and television transmitters
- Electronic test equipment for example signal generator and hearing aids
- Radio broadcasting/transmitting and receiving for example RFID
- Clock and timing signals that regulates control, computers and clocks
- Music and sound produced by electronic organ, synthesizer, and beepers
- Converts direct current (DC) supply to alternating current (AC) signals
- Heat generation in induction and dielectric heating f.e microwave oven
- Imaging for example ultrasound
- Cleaning as in ultrasonic cleaner
The use of oscillators are too numerous to mention. Can you think of any other use?
Electric motors find applications in many home electrical appliances, medical and industrial equipment and vary in design, sizes and shapes from miniature to giant size to fit in position and to suit its intended use.
Electric motor is vital to the function of a suction machine, electric cooling fan, compressor, some nebulizer, baby and laboratory incubator, zoom mechanism in microscopes, motorized up and down movement, collimator of X-Ray machine, blower, centrifuge, blender, mixer lust to mention but few.
A motor may be DC or AC powered with variations in speed but DC motors are usually more powerful however, some are universal that is you can power them by DC or AC as the case may be. When you understand how a motor works, its not difficult to understand the working principles of the rest because this device works by the magnetic effect of electricity.
Simply put, motor effect is produced when opposing magnetic poles interact where one is stationary and the other can move freely. The stationary magnet (permanent or electromagnet) is refers to as stator; the free electromagnet is refers to as the rotor. I will not go into details of the operation here but you can watch this video to see how this man demonstrated the working principles of electric motor.
I enjoin you to watch this video to the end for insight on basic principles of motor from electromagnets. In this video check to see how they implement the brush and commutator but remember not all motor uses brush and commutator. You can vary the speed and torque of some motor to suit your purpose; for some motor, you can also change direction to rotate either clockwise or anti-clock wise.
To get the best out of a motor, its important to know how you can vary the speed and change its direction of movement as desired. Bigger electric motor include over current and overload protection as part of its control.
Check this out for ac motors in action:
Why do you receive a nasty shock from a metallic object like a cylinder for example when the particular object was never plugged to electricity? This is the question I asked a colleague we worked together on the items from which he received the shock. The object is a sub-assembly item and until we add every other component there is no means to plug it to a socket. To confirm his claim I touched one of the stacked item and behold I got a sting!
However when I think over the problem, I concluded that static electric charge built on the stacked items during packaging and strapping with sheet of nylon materials. One item separated from the other by a kind of plastic material and they strapped them while moving hence static build up. For safety before handling the Item, we discharge them by using a metal to bridge them together two at a time and we clearly sees bluish spark. The discharge of this electricity is very dangerous on electronics damaging electronics devices; hospital especially emergency and operating rooms for risk of explosion with anesthetic agents. This is why it is important to prevent it.
And what is this static charge?
Static electricity manifest when two insulators for example; hair and comb; fur and silk; carpet and rubber and lots more rub against each other separated, separating and build up charges resulting in accumulation of positive and negative charges build up. Though there are positive applications elsewhere, this is very serious issues in electronics, hospital and some industries set up like paint and flour. Effects of electrostatic or static electricity are– electric shock, deafening sound, lightning, fire and explosion, damaging to electronics
Other obvious examples and effect of static electricity also known as electrostatics
- Walking along a carpeted floor in the winter in a dry and hot environment will generate enough static electricity to shock you if you touch a door knob or any other conductor like metal object for example.
- Static electricity is much pronounced in lightning bolts (thunderbolts) ripping through the sky with light and sound.
The damaging effects of electrostatic is felt when a charged human body discharges through a sensitive electronics such as computer, ultrasound machine, ECG machine, semiconductor materials and lots more. The damage is of two kinds gradual and instant resulting in intermittent or immediate failure of components, circuit boards and the electronic equipment.
- There is also the danger of fire and explosion if this occurs in Operating Room (Operating Theater) of hospital or any place where volatile anesthetic agent and mixture of chemical is in use. In Operating Room environment, there is risk of fire and explosion due to volatile anesthetic fluids and gases where an anti-static material is not used.
In summary the effects of electrostatic or static electricity are– electric shock, deafening sound, lightning, fire and explosion, damaging to electronics
Is it not wise to guard against the negative effects of static electricity?
Due to devastating effects of ESD, precautions should be taken to prevent it. How do we prevent ESD? To prevent occurrence of ESD, you need to do the following:
- Increase Relative Humidity (RH). Increase moisture. Relative humidity is inversely proportional to static electricity. Low RH results in high static electricity and vice versa. 40% to 60% RH is recommended, where RH is below 40% there is high risk of Electrostatic discharge.
- Use of antistatic mats/carpets, floor, clothing and footwear. You should remove any static electricity from your body before you start building your projects or working on any sensitive electronics to avoid damaging your electronics and components. The best way to do this is to ground yourself to allow any static electricity built up in your body to flow away into the ground. How would you do that? Build your projects, troubleshoot and carry out your repair put on proper conductive wrist wrap which connects to the mat. An anti-static wrist wrap works like a lightning rod, diverting the electricity into the wrist wrap. The mat is permanently connected to the general mass of earth; another way is to strap yourself to the metal chassis of the instruments to ensure you stay at the same potential thus not building up damaging static electricity.
The antistatic mats, wrist straps, floor, clothes, footwear are made of materials with good conductivity. (Anti-static shoes should not be confused with insulating shoes, which provide exactly the opposite benefit — some protection against serious electric shocks from the mains voltage)
This means that you are permanently grounded while you are working which ensures static is not able to collect in your body.
An ophthalmoscope be it direct or indirect type is handy tool in eye-care delivery services and its portable and contains lenses, mirror and bulb and as such handle with respect. To have the best experience with this device, proper care and maintenance are of necessity. Consider the points below to ensure that your ophthalmoscope gives you years of dependable service.
Rusted rheostat; broken switch; Stained Optics; Broken or Misaligned lenses; Dimmed or darkened bulb surface; Power box and cable (this concerns the indirect ophthalmoscope),
One of the most common problems of ophthalmoscope especially, battery operated is the electrical contacts due to come as results of leaving batteries in the handle or battery compartment for a long time thereby corroding the contacts and spoil it. The corrosion could affect the rheostat or the pin contacts or both. Most times you could get the ophthalmoscope working by cleaning the corroded parts with alcohol or spirit. To clean the contacts you need to access the switch/control unit and this done by following a simple instructions‘how to dismantle a direct ophthalmoscope.
To forestall this problem:
Periodically check the condition of the batteries in your ophthalmoscope, making sure there is no sign of corrosion or oxidation. Always replace both batteries when changing them; alkaline batteries are good for your battery handles and if you will not use this instrument for an extended period of time, remove the batteries and store it within its protective case.
Replacing both batteries at the same time will ensure the bulb last longer, however with the new LED bulb technology in this ophthalmoscope, the defects in any of the used battery has little effect except to prevent corrosion to the contacts and switch systems.
Clean the exterior of your ophthalmoscope;
With a 70% isopropyl alcohol solution and soak a lint-free cloth. Wipe down the exterior of the ophthalmoscope head and handle, cleaning all external surface areas. Take care to prevent excess liquid from seeping into the components. I have cleaned many ophthalmoscope with mild soap solution and well wiped clean dry with water moistened lint free cloth . Best practice is to prevent damages to the aesthetic of the instrument. You can substitute isopropyl alcohol with commonly used, EPA- registered hospital disinfectant wipes for cleaning purposes if desired, but yield to users’ instructions from the manufacturers.
Cleaning the Optical Surfaces:
It is important to note that solution residue on the magnifying lenses may decrease device performance, carefully wipe clean all excess cleaning fluids from the surfaces of the lenses. You may clean the lenses of the instrument head cleaned with a lint-free cloth or lens paper.
You could prepare a mild soap solution and soak the optics in it (after you might have dismantled the ophthalmoscope) for proper cleaning after which you thoroughly rinse them after which you get them cool dry air.
When not in use, keep the instrument in the case provided.
The fundamental application of transformer includes Isolation Protection ⚡ Voltage Conversion as you normally encounter in distribution and power supply and Impedance Matching as employed for instance in amplification Some people are confused when they encounter transformer with multiple leads whether they are troubleshooting or fabricating, and some of the reasons are they don’t know which…
Introduction/Purpose Direct ophthalmoscope is an eye care instrument most commonly used for routine examination of the fundus and can also be used to examine the ocular structures of the eye from the anterior surface to the retina. Instrument for eye exam: a medical instrument used for examining the inside of the eye to detect changes…