Friday, September 19, 2014

Build a Auto Anti Hijack Alarm Circuit Diagram

This Auto Anti-Hijack Alarm Circuit Diagram was designed primarily for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the Siren will sound.

Auto Anti-Hijack Alarm Circuit Diagram

Where it differs from the first two alarms - is in what happens next. Im obliged to Victor Montanez from the USA who suggested that the engine cut-out should not operate - until the vehicle comes to a stop. That way - the engine will not fail suddenly or unexpectedly. And the hijacker will retain control.

I havent been able to implement Victors excellent suggestion completely - because I couldnt think of a simple, reliable and universally applicable way of sensing when the vehicle has come to a stop.

Instead - I have postponed engine failure until the ignition is switched off. Once the thief turns off the ignition - the engine will not re-start. Clearly - there is no certainty as to when this will occur. But I think it will occur sooner rather than later. Because theres a strong possibility that the hijacker will turn off the ignition - in an attempt to silence the siren. 

 Auto Anti-Hijack Alarm Circuit Diagram

Auto Anti-Hijack Alarm Circuit Diagram


As well as acting as a Hijack Alarm - this circuit offers some added protection. Like the Enhanced Hijack Alarm - it incorporates Jeff Chias suggestion. That is - every time the ignition is switched on - the alarm will trip. So it will protect the vehicle whenever you leave it unattended with the ignition switched off - even overnight in your driveway.

Importance
Before fitting this or any other engine cut-out to your vehicle - carefully consider both the safety implications of its possible failure - and the legal consequences of installing a device that could cause an accident. If you decide to proceed - you will need to use the highest standards of materials and workmanship.

Notes
Youre going to trip this alarm unintentionally. When you do - the LED will light and the Buzzer will give a short beep. The length of the beep is determined by C4. Its purpose is to alert you to the need to push the reset button. When you push the button - the LED will switch-off. Its purpose is to reassure you that the alarm has in fact reset. 

If the reset button is not pressed then - about 3 minutes later - both the Siren and the Buzzer will sound continuously. The length of the delay is set by R8 & C5. For extra effect - fit a second siren inside the vehicle. With enough noise going on - you may feel that its unnecessary to fit the engine cut-out. In which case - you can leave out C7, D8, R12, R13, Ty1 & Ry2.

When the ignition is switched on - C3 & R4 are responsible for tripping the alarm. By taking pin 1 low momentarily - they simulate the opening of a door. If you dont want the alarm to trip every time you turn on the ignition - simply leave out C3 & R4. 

Because the voltage on C3 may be reversed - the capacitor needs to be non-polarized. But connecting two regular 22uF capacitors back to back as shown - will work just as well. Because non-polarized capacitors are not widely available - the prototype was built using two polarized capacitors.

To reset the circuit you must - EITHER turn off the ignition - OR close all of the doors - before you press the reset button. While BOTH the ignition is on - AND a door remains open - the circuit will NOT reset.

The reset button carries virtually no current - so any small normally-open switch will do. Eric Vandel from Canada suggests using a reed-switch hidden behind (say) the dash - and operated by a magnet. I think this is an excellent idea. As Eric said in his email: - "... that should keep any thief guessing for a while."

Veroboard Layout

Veroboard Layout
 
How you prevent the engine from starting is up to you. It should happen when Ry2 de-energizes. The contacts of Ry2 are too small to do the job themselves. So use them to switch the coil of a larger relay. Remember that the relay must be suitable for the current its required to carry. Choose one specifically designed for automobiles - it will be protected against the elements - and will give the best long-term reliability. You dont want it to let you down on a cold wet night - or worse still - in fast moving traffic!!! Remember also that you must fit a 1N4001 diode across YOUR relays coil - to prevent damage to the Cmos IC
YOUR relay should drop-out when Ry2 de-energizes. Wire YOUR relay so that when it drops-out the engine will not start. Because turning-off the ignition will cause both Ry2 and YOUR relay to de-energize - the standby current will be low - and the engine will be disabled while the vehicle is parked.
The circuit board must be protected from the elements. Dampness or condensation will cause malfunction. Fit a 1-amp in-line fuse AS CLOSE AS POSSIBLE to your power source. This is VERY IMPORTANT. The fuse is there to protect the wiring - not the components on the circuit board. Please note that I am UNABLE to help any further with either the choice of a suitable relay - or with advice on installation.
Both the Siren and the Buzzer will go on sounding until the alarm is reset. The circuit is designed to use an electronic Siren drawing up to about 500mA. Its not usually a good idea to use the vehicles own Horn because it can be easily located and disconnected. However, if you choose to use the Horn, remember that Ry1 is too small to carry the necessary current. Connect the coil of a suitably rated relay to the "Siren" output. This can then be used to sound the Horn.


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Friday, January 10, 2014

Super Hi Fi Headphone Amplifier Circuit Diagram

This is a Super Hi-Fi Headphone Amplifier  Circuit Diagram.




Super Hi-Fi Headphone Amplifier Circuit Diagram


Super Hi-Fi Headphone Amplifier Circuit Diagram




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Most mobile phones on the market today or a single CPU

Most mobile phones on the market today or a single CPU.
S40, nokia mobile phone operating system developed by the face of low-end customers, support kjava the development, its processor efficiency is not high, low memory, screen size 128 * 128. S60, is based on the Symbian operating system, that is, before the epoc processor arm9 high processing efficiency, considerable memory, screen size is 208 * 176 support both kjava and C + + development. S90, is a handheld device, the Symbian operating system, but robust, equivalent to a PDA. In fact, says the technology to the S40 with the S60 is the difference between system platforms, like WIN98 now WIN2000 but the phone unlike the PC, the screen size is indeed a mark. The technical review of  Cell Phone Jammers is important too.In order to prevent dust and foreign matter into the sound chamber, can be affixed inside the enclosure dust network, for the beautiful, the sound hole on the outside can be affixed to the nickel plate, PC tablets, and other decorative pieces, small mesh diameter of the nickel plate 0.3mm, nickel plate, inside the enclosure can not affixed to the dust network. speaker after tune the low frequency part of the main impact of ringtones, high frequency part is smaller, you can not do the requirements. In order to get good bass, no component interference on the motherboard, you can use the antenna bracket and motherboard with affixed foam speaker Tune closed after the formation of the sound chamber in order to get more awesome bass vibration effects, speakers, family speaker.
Give priority to the purchase and the successful capital increase, will promote Symbian to the next stage of growth. Today, shareholders and unified commitment to a strong proof of the Symbian are fully capable to meet the needs of current and future industry development. Yoshiaki Kushiki, president of Panasonic Mobile Communications, said: "Panasonic is fully exercised the right of first refusal to the Psion shares. This shows our strong commitment to the independence of Symbian through a broad, balanced and equity basis to maintain this independence is critical This will be conducive to the Symbian operating system in the mobile phone industry to maintain its objective criteria, and continue to receive long-term support and backing of a number of manufacturers and network operators. " The individual quality assurance can not assure the quality of  Cell Phone Jammers  totally.
We must consider the draft between the various shell upper and lower shell along the mold more than 3 degrees, metal decorative pieces around the draft to be more than 5 degrees. Appearance of the side is the outer contour surface of the phone, a good curve out surface, described line be sure to close the ID of the wireframe ID creative respect the basic accomplishment of structural engineers and lines but also try smoothing as much as possible uniform change of curvature, draft angle should be taken into account, if the ID of the line pull draft angle and structural requirements are inconsistent, and ID consultation appearance by the structure in the description line directly to fix the draft angle of the contour lines, if the plastic shell to retain the draft angle is larger ID of the creative destruction plastic mold, you might consider doing the four sides of line spaces, after all, the phone is a high-end consumer goods, this investment is worth. It is to strengthen the quality control of  Cell Phone Jammers .
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Electrical Schematic Symbols

Electrical Schematic Symbols:

Electrical circuit schematic symbols are graphical sign, that is used to design electronic, electrical circuit schematic diagram. There is a quite adequate collection of symbol for electrical, electronic circuit. You can use this high quality schematic symbols to design your own schematic circuit diagram. Download high quality electrical schematic symbols image.

Electrical-Symbols
High Quality Electrical Schematic Symbols


Click on the image of Schematic Symbols  to enlarge. 
Special thanks to the author of www.ARRL.org  for these high quality electrical schematic symbols.
This circuit schematic symbols are for educational purposes only, not for any industrial use.
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