Silicon Chip's 'Electronic Projects for Cars Volume Two' is a 128-page compilation of auto-related electronic projects that have been previously been published in the regular Silicon Chip magazine. The seventeen kits cover a wide range of applications - which we'll come to - and vary from a simple 5-minute project with just five components to more in-depth projects requiring considerable assembly experience.
The kit most likely to appeal to people with next to zero electronic experience is a blocked filter alarm, which involves slight modification of a small pressure switch, connection to the post-filter side of an airbox and the simple wiring to a buzzer or LED.
Another project not requiring soldering to a PCB is the Little Dynamite Subwoofer. Using a pre-built woofer enclosure (fully carpeted and including terminals), a 10-inch driver and a custom-built port, the Little Dynamite Subwoofer - which was developed using a highly regarded subwoofer design software package - is relatively easy to build. Once completed, the driver and enclosure are said to offer strong response down to 15Hz - and that's low!
The ideal match for the Little Dynamite Subwoofer is the Neon Tube Modulator project. Although this will involve soldering to a PCB, the kit is quite straightforward and allows you to pulse up to ten neon tubes to the bass beat. Great for competition sound-offs.
Another simple project covers the conversion of filament lamps (for centre high-mount stop lights, trailer lights and more) to ultra-bright LEDs. The advantage of these high-intensity LEDs - apart from looking much tricker - is a faster light-up time (the time it takes for the brake light to come up once the brake switch has been triggered). The LEDs are also said to place less load on the vehicle electrical system, require less space, generate little heat and have a long service life. Ten pages are dedicated to these conversions, including an example conversion on the centre high-mount stop light on a Honda Accord.
Also in the fairly easy basket is the Headlight Reminder. Fitting in a small box, this project sounds a buzzer whenever you've left the headlights on and you open the door to leave. A neat feature is a timeout function that stops the buzzer after about 10-seconds. The Reminder is also compatible with different door switch wiring.
Flat batteries can also be avoided with the Digital Voltmeter project. Compatible with 12 or 24-volt systems, the unit is housed in a compact case and uses a 3-digit LED numerical display of voltage. Auto display dimming and a minimum voltage hold display (handy for seeing what voltage falls to while cranking) are also featured.
With a few more components (but still quite achievable) is the Booze Buster Breath Tester project. As quoted, "it might not stand up in court" but for a total cost of $30 it is a cost-effective guide. A 10 LED display indicates your blood alcohol level and the unit plugs into your car's cigarette lighter. Oh, and - once you've assembled the project - your reward is the calibration procedure...
A well-proven kit is the Engine Immobiliser - Mark Two. EI2 works on the principle of intermittently shorting out the switching transistor or points that control the (single) coil; the upshot is the car will only run for about 2 seconds unless the immobiliser is deactivated via a concealed switch. No damage is caused to the vehicle's ignition system. The kit has only 20 components - plus a few miscellaneous parts - and is quite simple to assemble. A neat kit.
When it comes to motorcycles there's very little in terms of security - the Motorbike Alarm is a very cost-effective solution, however. Using ether a motion detector or a mercury switch (which settles into its position when the bike is put on its stand), the system is extremely tamper-proof (a common problem of bike alarms). A loud piezo siren warns of attempted theft. Note that, with just a handful of components, the project is quite easy to assemble.
Another ol' favourite is the 10 LED mixture meter for EFI cars (as covered previously in AutoSpeed). Simply connect this simple circuit to switched 12V, Earth and the output from an exhaust gas oxygen sensor. The approximate air-fuel ratio is displayed on the 10 LED scale, with the red LEDs typically arranged to warn of a lean condition. Note that this style of air-fuel ratio meter is also responsive enough to show rapid closed-loop mixture oscillations. We never modify a car without one!
And now we move on to the more complex projects...
The Speed Alarm project needs no real explanation. We will, however, say it is adjustable in 5 km/h increments and sounds a buzzer (either once or repeatedly during overspeed) and illuminates a LED upon overspeed. Hysteresis - alarm on to alarm off speed - comes set to 1.25 km/h (ie you have to drop 1.25 km/h below the speed alert value for the alarm to switch off). A 3-digit numerical LED display can be used to display real-time vehicle speed at speeds up to 159 km/h (up to 245 km/h with optional software) and with 1 km/h accuracy. The two stacked PC boards are quite highly populated but the end result doesn't look as professional as, say, a VDO speed alert.
Another proven kit is the Universal High-Energy Ignition System, which reduces the need for regular tune-ups in cars with Kettering ignition systems (where the points switch the current through the coil). A breakerless system can also be created given you obtain an interchangeable dizzy with a Hall-effect or reluctor trigger. Furthermore, it has the potential to replace a faulty ignition module in non-EFI cars already fitted with Hall-effect or reluctor distributors. Dwell extension is another feature, which can result in better performance, smoother idle, improved fuel economy and better cold starting. This kit involves the soldering of quite a few components onto the PC board and fits neatly inside a diecast aluminium case equipped with wire grommets.
Another similar kit is the High-Energy Capacitor Discharge Ignition System. Instead of using transistor assistance like the above kit, this example uses a CDI approach giving very fast spark rates and, therefore, excellent spark energy even at very high rpm and with high combustion pressures. Another key feature of this kit is the multiple spark discharge (MSD) function, which produces up to 10 sparks each time a combustion chamber is to be fired. Not surprisingly given its extra function, this unit is more difficult to assemble than the universal HEI as above.
Also on the subject of ignition systems is the kit - Programmable Ignition Timing for Cars. This is designed for use on older-tech cars fitted with either the HEI or CDI projects mentioned above. It allows you to store two sets of timing data (ideal for switching between two different fuels), and you can set the rpm at which advance begins, and the two stages of advances depending on revs. The stored data is also protected by a two-digit security code, which must be entered into the keypad control. Although quite detailed to integrate into a vehicle, this is another proven project.
A project with great potential for a creative mind is the 4-channel, rolling-code UHF remote control. This allows you to, say, operate a garage door or home security system from within the comfort of your car - up to four different devices can be switched from the remote unit. Up to 16 remotes can be used with the one receiver unit. Note, though, the receiver unit is not designed to directly control high voltages - it's rated up to 12A at 12V DC. Although some sections come pre-assembled, this project is not one for beginners - there are about 40 components.
The Silicon Chip Rev Limiter project serves to cut 8 sparks in every 16 to "softly" restrict rpm to an adjustable level; the rev limit function is not necessary on modern cars that are already factory-fitted with a rev limiter. Equipped with three sequential LEDs on the face, it also doubles as a gearshift indicator. The system works best with Hall Effect, reluctor pick-up or a low voltage signal from the ECU (rather than a Kettering non-transistorised ignition system). There are many components that need soldering onto two PCBs.
A variation of this project is the SC Digital Tacho, which is an ideal fitment to cars not factory-fitted with a tacho. Compared to other numerical digital tachos, this unit shows the rpm on a 4-digit LED display and a bar graph, which clearly shows when maximum revs are approaching. Note that the bar scales is automatically scaled according to the preset rev limit. It is designed for up to 9900 rpm with 100 rpm resolution. In addition to showing revs numerically and on a scale, this kit also has the ability to illuminate several of the bar graph LEDs at a given rpm - a shift indicator, in other words. The third important function is a rev limiter, which features an adjustable hysteresis. Configurable for engines 1 to 12 cylinders, the project is - again - quite complex with two stacked PCBs. Ten pages are dedicated to explaining this kit.
So there's the run-down of the seventeen projects contained in the compilation. Each kit is covered by colour photographs, diagrams, relevant breakout boxes and every instruction you need to build the kit from start to finish. At AUD$12.95 it's not particularly cheap for a collection of re-runs, but it's still a lot cheaper than ordering all the relevant back-issues of Silicon Chip!
SC's Electronic Projects for Cars Volume Two is available from www.siliconchip.com.au
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