coll circuit

For those who love tunes and the ability to take them along wherever you may roam, there are some great auto sound systems that allow you to basically plug in your favorite tunes to play as you go. It doesnt really matter which style of MP3 player you use, most of the newer auto sound systems at least have the ability to read and translate the material from these players into great music for you to enjoy on your ride by simply plugging your MP3 player into the car stereo.

Many of us find that lugging around an MP3 player with all of our favorite tunes (or at least most of them-with up to 40 gigs of hard drive space it might take a while to fill completely) is much easier and more practical than attempting to lug around a huge case of CDs. It is also great for those of us who find ourselves disappointed when we purchase CDs only to find that we really only like one or two songs. Now we can simply download the songs we know and love while avoiding those we are uncertain about or at least waiting until more songs come out before deciding whether or not to purchase the entire collection of songs. Having an auto sound system that allows you to enjoy the convenience of simply plugging in either your MP3 player or a memory card or stick in order to have your favorite songs at your finger tips at all times is fantastic.

I dont know about you, but I am absolutely hooked on audio books. I love to read and find so little free time in which to get my feel of the latest and greatest best seller. Audio books allow me to hear the stories Ive been eagerly awaiting at my convenience and in my SUV as Im making my daily commute or running errands. These books are also a great way to enjoy long car trips. You can even check your local library in order to find an excellent selection.

I typically try to find stories that might interest the children on long car rides as well (such as the Harry Potter books or The Polar Express). This instills a love of reading in them and I dont have to worry about the stray grown up word that some audio books contain. Good auto sound systems not only play great music but also sound wonderful when it comes to the spoken word as well. This is not only true when it comes to books on tape, CD, or MP3 but also talk radio and national news stations as well.

When you begin your search for your next auto sound system make sure you consider all the possible features you may wish to include. You can find sound systems today that include GPS, DVD players, navigational tools, CD players, MP3 players, satellite radio receivers and countless other nifty features. Choose the auto sound system that will suit your needs and interests best and enjoy it for as long as you can. A good sound system is something that will stay with your car, truck, or SUV so it is best to make that particular investment long before you plan to trade your vehicle in on another. At the same time a good auto sound system can be an excellent incentive to hold onto your vehicle a little while longer.

A tachometer is a device which is used for measuring vehicle engine RPM. Thus, it is basically used for checking the performance of the engine and helps an auto mechanic to understand the condition of the engine so that it can be corrected or optimized as per the desired specs.


Generally a tachometer may be considered an expensive equipments as these are highly accurate and intended for obtaining correct RPM rates of the concerned engine under test.

The conventional units are therefore very sophisticated and generate highly accurate results while testing.

However it doesnt mean that a simpler version cannot be built at home. With electronics at its best today, making a tachometer circuit at home isnt at all difficult. Whats more the results obtained from such circuits are fairly accurate and provides the required data for assessing the overall working condition of the system.

The circuit diagram shows a simple configuration utilizing the IC 555. The IC is basically configured as a monstable multivibrator.

The pulse is derived from the spark plug and fed to the end of R6.

The transistor responds to the pulses and conduct in accordance with triggers.

The transistor activates the monostable with every rising pulse of the input.

The monostable stays ON for a particular moment each time its triggered and generates an average ON time at the output which is directly proportional to the average trigger rate.

The capacitor and the resistor at the output of the IC integrate the result so that it can be directly read over a 10V FSD voltmeter.

The pot R3 should be adjusted such that the output generates the exact interpretations of the fed RPM rates.

The above setting up must be done  with the help of a good conventional tachometer unit,



Parts List

Primarily there are two AC mains voltage levels that are specified by countries across the globe. These are 110V and 220V. The USA works with a 110V AC mains domestic line while European countries and many Asian countries supply a 220V AC to their cities. Folks procuring imported gadgets from a foreign region having a different mains voltage specs find it difficult to operate the equipment with their AC outlets because of the huge difference in the required input levels.

Though there are 220V to 110V converters available for solving the above issue, these are big, cumbersome and immensely costly.

The present article explains s few interesting concepts which can be possibly implemented for making compact, transformerless 220V to 110V converter circuits.

The proposed homemade converters can be customized and dimensioned as per the gadget size so that these may be inserted and accommodated right inside the particular gadget. This feature helps to get rid of the big and bulky converters and helps to keep away from the unnecessary mess.

CAUTION: ALL THE CIRCUITS DISCUSSED HERE HAVE POTENTIALS OF CAUSING SEVERE LIFE AND FIRE HAZARDS, EXTREME CAUTION IS ADVISED WHILE GETTING INVOLVED WITH THESE CIRCUITS.

All these circuit diagram have been developed by me, lets learn how they can be constructed at home and how the circuit functions:

Using Only Diodes

The first circuit will convert a 220V AC input to any desired output level from 100V to 220V, however the output will be a DC, so this circuit may be used for operating a foreign equipment which might be employing an AC/DC SMPS input power supply stage. The converter will not work with equipment incorporating a transformer at its input.


As we all know that a normal diode, like a 1N4007 drops 0.6 to 0.7 volts across it, when a DC is applied, means that many diodes put in series would drop the relevant amount of voltage across them.
In the the proposed design, in all 190 1N4007 diodes have been used and put in series for acquiring the desired level of voltage conversion.
If we multiply 190 by 0.6, it gives around 114, so thats pretty close to the required mark of 110V.

However since these diodes require an input DC, four more diodes are wired up as a bridge network for the initially required 220V DC to the circuit.
The maximum current that can be drawn from this converter is not more than 300 mA, or around 30 watts.

Using a Triac/Diac Circuit

The next option presented here has not been tested by me, but looks good to me, however many will find the concept dangerous and very undesirable.
I designed the following converter circuit only after doing a thorough research regarding the involved issues and have confirmed it to be safe, but its my personal point of view, if you find it undesirable better do not try this.

The circuit is based on the regular light dimmer switch circuit principle, where the input phase is chopped at the particular voltage marks of the rising AC sine wave. Thus the circuit can be used for setting the input voltage at the required 100 V level.
One big issue involved with this circuit is back EMF that might be generated  from the transformer of the gadget, this might instantly fry the triac or the diac. Although sufficiently advanced and high power components have been included in the design, an effective snubber circuit stage was felt imperative and therefore the RC network across the triac has been stationed.

The pot shown in the circuit should be adjusted for obtaining the required 110V at the output terminals.
A 500 watt iron element coil resistance may be introduced in series with the load for extra safety.

Alternatively a simpler version of the circuit can be made, where the main high triac is operated via a cheap light dimmer switch for the intended results.

Using an Autotransformer Cocept

The last circuit in the order is perhaps the safest from the above because it uses the conventional concept of transfering power through magnetic induction, or in other words here we employ the age old autotransformer concept for making the desired 110V converter.
However here we have the freedom of designing the core of the transformer such that it can be stufed inside the particular gadget enclosure which needs to be operated from this converter. There will be always some space in gadgets like an amplifier or other simlar systems, which allows us to measure the free spave inside the gadget and  customize the core design.

I have shown the use of ordinary steel plates here as the core material which are stacked together and bolted across two of the sets.
The bolting of the two sets of lamination provides some sort of looping effect, generally required for efficient magnetic induction across the core. The winding a single long winding from start to end, as shown in the figure. The center tap from the winding will provide the required approximate 110 V AC output.