Diagram SOlution

Showing posts with label your. Show all posts

Monday, October 20, 2014

Protection For Your Electrical Appliances

Here is a very low-cost circuit to save your electrically operated appliances, such as tv, tape recorder, refrigerator, and other instruments during sudden tripping and resumption of mains supply. Appliances like refrigerators and air-conditioners are more prone to damage due to such conditions. The simple circuit given here switches off the mains supply to the load as soon as the power trips. The supply can be resumed only by manual intervention. Thus, the supply may be switched on only after it has stabilised.

Circuit diagram :

Protection For Your Electrical Appliances

The circuit comprises a step-down transformer followed by a full-wave rectifier and smoothing capacitor C1 which acts as a supply source for relay rl1. Initially, when the circuit is switched on, the power supply path to the step-down transformer X1 as well as the load is incomplete, as the relay is in de-energised state. To energise the relay, press switch S1 for a short duration. This completes the path for the supply to transformer X1 as also the load via closed contacts of switch S1. Meanwhile, the supply to relay becomes available and it gets energised to provide a parallel path for the supply to the transformer as well as the load.

If there is any interruption in the power supply, the supply to the transformer is not available and the relay de-energises. Thus, once the supply is interrupted even for a brief period, the relay is de-energised and you have to press switch S1 momentarily (when the supply resumes) to make it available to the load. Very short duration (say, 1 to 5 milliseconds) interruptions or fluctuations will not affect the circuit because of presence of large value capacitor which has to discharge via the relay coil. Thus the circuit provides suitable safety against erratic power supply conditions.

Author : MALAY BANERJEE

Sunday, January 12, 2014

Measure your stress level – Tension meter

If you, like so many other people in this day and age, arrive home from work stressed out and with the problems of the day still lingering,this simple little instrument will go a long way to relieving nervous tension.

Of the various types of feedback devices, probably the best approach for the amateur experimenter is the Galvanograph, better known as the Galvanic Skin Response Monitor. The instrument described here relies for its operation on changes in skin resistance in sympathy with changes in emotional state. An increase in tension level reduces skin resistance and, conversely, a decrease in tension is accompanied by an increase in skin resistance.
The correlation between emotional stress and skin resistance is still not fully understood. What is known, though, is that minute changes in the permeability of the skin produce corresponding voltage variations across two electrode pads attached to two fingers on the same hand.

Tension Monitor meter circuit

These signal fluctuations are amplified and fed to an oscillator to produce an audible tone. A decrease in pitch therefore signifies a decrease in tension, and vice-versa. A visual indicator in the form of a panel meter also aids the user in monitoring tension levels. The monitor is quite sensitive to fluctuations. During use, a sudden moment of stress, even a deep sigh, will increase the pitch and cause a shift of the meter needle. Circuit Details In the circuit diagram of Fig.1, IC1 is configured as an astable multivibrator to drive an 8-ohm miniature speaker LS1 via capacitor C3, resistor R6 and volume control potentiometer VR2. The latter allows users to set a desired level and avoid it becoming a distraction.
Whereas the trigger input of IC1 is normally connected to the positive rail via a resistor in a conventional 555 oscillator, here it is connected via resistor R4 to the emitter of transistor TR1. The base of TR1 is connected between one electrode pad and the voltage divider formed by potentiometer VR1 and resistor R1. It will be seen that with the pads fitted to the fingers, the tone level will be dependent on the setting of VR1 and skin resistance. Resistor R2 in the transistor base is necessary should the pads be accidentally touched together. A 1mA meter is fitted in the collector line, along with R3, as a visual indicator. Although not essential or intended to measure current levels, it does help to emphasize fluctuations in emotional level.
The design of the pads is not critical. For the prototype, stripboard was used. The tracks were wired together at one end and connected to a 30cm length of twin lighting flex. The pads were then glued to Velcro straps. When the unit is first switched on, a highpitched tone should be heard, rapidly diminishing and ceasing. Turn the Sensitivity control VR1 to the minimum setting. Attach the electrodes to the fleshy pads of the first two fingers on the less-dominant hand with the Velcro straps, firmly but not tight. Rest the hand comfortably and keep it reasonably still, allowing half a minute for the pads to “bond”. Normally, at the minimum setting, the oscillator will hardly tick over, unless the user is in a high state of anxiety. Keep in mind that any form of stimulant, and that includes tea, coffee, alcohol and cigarettes, will reduce one’s capacity to relax. Rotate the control until a medium pitched tone is obtained and apply your relaxation technique. The monitor does not teach any method of meditation or relaxation; it only monitors the effectiveness of the technique applied. The tone should slowly diminish, with fluctuations as unconscious thoughts flit across the mind.When the sound ceases altogether, repeat the above procedure by increasing VR1. Twenty minutes is considered by therapists to be an adequate relaxation session.

Saturday, November 23, 2013

The Risks of Self Installation of your Auto Sound System

The risks of installing your own auto sound system may be greater than you realize. The fact is that there are people that are professionally trained in the installation and proper handling of these delicate sound systems for a reason. If it werent a difficult task they wouldnt be able to demand the rather hefty price tag that most installation centers charge. The problem is that mistakes can actually cost more than the installation. If you arent one hundred percent certain that you can handle the installation process alone it is best to leave it up to the experts.

To prove my point, I will give you my very own personal story of how auto sound system installations can go horribly (well, perhaps hilariously would be the better choice of words in my particular situation) of course. You see I wanted a CD player in my mini van about 13 years ago. This was back in the dark ages when these types of sound systems were still relatively new and on the cutting edge when it came to technology.

These types of auto sound systems were definitely not the norm as they are in todays cars. I was commuting 3 hours (round trip) each day at the time and some of the time was spent among the corn fields where there were no towers broadcasting radio signals anywhere nearby. Im sure you can see why I felt I needed a CD player. At any rate, my wonderful dear old dad installed my brand new car (well mini van) stereo for me and all seemed to be going well until we realized that the horn no longer worked and that in order to actually use the stereo, the headlights must be on (this was also before daytime running lights were the norm as well).

Now that youve finished laughing Im sure you can understand why I am a huge advocate for having professional handle issues of installation when it comes to auto sound systems. It isnt that my dad, whom I love dearly for the effort, was incompetent when it comes to technical matters, in fact, he is highly skilled in these sorts of things ordinarily, it is simply that car stereos are so terrible complicated that it takes more than merely reading a set of instructions in order to get the maximum effect from your installation endeavors.

I have heard horror stories, particularly related to in dash installations that have resulted in some people having to make serious and costly repairs to their cars in order to fix the damage inflicted by installations by those who either lacked the proper tools, proper training, or a little bit of both for installing auto sound systems. While some drivers dont spend all that much time in their vehicles on any given day there are many commuters who put many miles on their cars, trucks, or SUVs during the course of a week. For these drivers it is often very important that they have the best possible sound systems for their vehicles. They will rely on their stereos to find out about weather conditions, traffic tie-ups, news, and possibly even entertainment during their long drives. If sound and music plays an important role in your life, dont you deserve the best auto sound system possible?