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For car alarms, emphasis should be put on hearing the audible alert and identifying it as belonging to your 'wheels'. Unfortunately, modern car alarm systems seem to have more or less the same alarm sound especially if they are from the same brand. Also, to comply with legal noise restrictions, the alarm sound is not always loud enough to be heard if the car is parked down the road. Circuit diagram : Simple Car Alarm Sound Booster Circuit Diagram The circuit shown here is designed to help boost the alarm sound by also activating the car's horn(s) when the alarm goes off. lnternally the car alarm system often provides a signal that activates the (optional) engine immobilizer and/or volume (ultrasound) sensors. This signal usually goes Low upon sys-tem triggering and high again when the alarm system is deactivated. The alarm activation signal is fed to the circuit through Dl . When in idle state, T1 's gate is High and consequently the FET conducts,  keeping  power ...

This is a very popular series of amplifiers audio users who require maximum aduio results and of course with a relatively cheap price. This circuit requires a minimum voltage and maximum 9 Volt and 30 Volt. This amplifier circuit using ic TDA2003, which is used in car audio power, because of making these amplifiers can easily be made on each speaker of the amplifier. By using ic and component quality is very good circuit used separately. The circuit can be seen below.   Technical information: Supply voltage = 12V Output             = 10W 

The ASUS Eee is a fantastic ultra-portable notebook with almost everything required for geeks (and nothing that isn’t). Plus it features fantastic build quality and is very well priced. If you live in New Zealand you can get them from DSE; at the time of writing they are the exclusive supplier. I worked out it’s the same cost as importing one once you include all the duties and tax, plus you get the advantage of a proper NZ-style mains charger. Anyway, being so small I thought it would be nice to be able to carry this around in the car. Unfortunately I couldn’t find a car charger available anywhere at the time so I decided to tackle the problem myself. As a bonus this provides an opportunity for an external high-capacity battery. Commercial Equivalent: I thought at this stage it would be worth noting that a commercial car charger is now available for less than it cost me to build this from Expansys and is available in most countries (select your location on their site). It outputs 9.5v...

SW Converter for Digital AM Car Radio Circuit Diagram This circuit is purposely presented with many loose ends (not literally, of course) to stimulate experimenting with RF circuitry at a small outlay. Looking at the circuit diagram you may recognize a modified version of the SW Converter for AM Radios described elsewhere in this issue. The modifications were necessary to make the circuit compatible with a digital rather than analogue AM car radio. The main difference between digital AM radios and their all-analogue predecessors is that tuning is in 9 kHz (some-times 4.5 kHz steps) in compliance with the international frequency allocation for the band. Obviously, that particular step size, desirable as it may be on MW, is a stumbling block if you want to use a digital AM receiver in combination with a frequency step-up converter for SW, where chaos reigns and there is no fixed step size. The first attempt was to make the crystal oscillator variable by about 5 kHz each way.   SW Co...

This hack illustrates how a car can be controlled from anywhere in the world by tapping into the disgnostic systems and onboard webserver of the car. The objective is to keep the car “live” and connected to the Internet 24×7 even when not being driven. It should run continuously without flattening the car battery by critically selecting a low-power computer. Also, the user should be able to start the engine, pop the trunk, lock/unlock, and view all vehicle diagnostics from his iPhone. The chosen car was a Mazda RX-8 as shown in the image below. It was released in 2004 and consists of 6-speed manual transmission with a 1.3L 13B-MSP RENESIS engine. The computer used in this hack is an Alix-1 which draws very little power but is fast enough to run a full Linux distribution system. To fit into a recess in the base of the RX-8 boot, a mounting frame was assembled. It has room to mount the Alix-1, a USB hub, a charge circuit, and a deep-cycle 28A/h sealed lead acid battery. The SLA battery i...

Here is very simple low-cost electronic circuit project of low state car battery indicator circuit. This electronic circuit diagram designed using few common electronic parts. This low state battery electronic project can be used to monitor car battery voltage. Low-Cost Low State Car Battery Indicator Circuit Diagram: The warning light LED indicates when battery indicates battery voltage falls bellow level set by 10k potentiometer, if the battery is defective or needs charging if cranking drops battery voltage bellow preset safe limit. This circuit project is very simple so it not requires some other explanation.

This circuit is used to monitor the battery voltage to display a dual-colored LED status of the battery to. If the LED “green”battery voltage exceeds 11.9 volts. If the yellow LED , battery voltage 11.9 to 11.5 volts. If the LED is “red” If the battery voltage below 11.5 volts. You can of course change the trigger points by the trimmer resistors and / or changing the value of the resistors in the divider. A dual op amp is used as a comparator. The green LED on the board, until the voltage exceeds 11.5 volts. The red LED illuminates when the voltage falls below 11.9 volts to the circuit. Therefore, in the 11.9 to 11.5 volts, both LEDs are on, producing a slightly yellow color. When the voltage falls below 11.5 V, the green LED , and now only the red LED flashes to indicate low voltage. Parts List R1=1K2 R2-3-4=680R R5=15K R6=10K R7-8-9-10=1K IC1=LM324 D1=5V6 /0.5W Zener D2-3-4-5=LED RV1=10K trimmer  Is recommended that multi-shaper for V1 and V2. Muti-trimmer makes it much easi...

Using a mobile phone while driving is dangerous. It is also against the law. However, you can use your mobile phone as a powerful music player with the help of a stereo power amplifier. This does away with the need of a sophisticated in-dash car music system. Most mobile phones have a music player that offers a number of features including preset/manual sound equalisers. They have standard 3.5mm stereo sockets that allow music to be played through standard stereo headphones/sound amplifiers. Nokia 2700 classic is an example. A car audio amplifier with 3.5mm socket can be designed and simply connected to the mobile phone output via a shielded cable with suitable connectors/jacks (readymade 3.5mm male-to-male connector cable is a good alternative). Fig. 1 shows the circuit of car stereo player. It is built around popular single-chip audio power amplifier TDA1554Q (IC1). The TDA1554Q is an integrated class-B power amplifier in a 17-lead single-in-line (SIL) plastic power package. Fig. 1: ...

This is the Simple Car Alarm Arming Horn Beep Canceller Circuit Diagram Project. It's a great convenience that most modern cars come with a built in alarm, however it is nothing but noise pollution that the horn sounds when the alarm is armed. Disconnecting the alarm system from the horn relay will eliminate this, but prevent the horn from sounding in the even of an actual alarm. This circuit serves to silence the arming beep yet maintain the alarm by introducing a small delay into the signal.    Car Alarm Arming Horn Beep Canceller Circuit Diagram       It sits between the alarm and horn relay. The alarm must provide a constant horn signal for at least 3 seconds before the horn relay is activated. That way the quick "beep" will never activate the horn relay, while the constant alarm signal will. Part           Total Qty.             Description C1 ...

Schematic- Click on the schematics to zoom in