GUIDE TO CAR POWER ADAPTERS With the ever increasing personal portable electronics and digital devices like CD player, Walkman, Camcorder, Digital Camera, Game Boy, DVD player and etc. It is money saving and environment friendly to use the available DC power from your car. However, there are so many DC adapters on the market, to choose the right one for your portables can be daunting for not so technical minded. 1. Safety comes first The adapter must have e-Mark and CE approvals. Modern vehicles have sophiscated and sensitive electronic systems which must be protected from interferences. Examples of electronic systems : the braking and speed control systems. The e-Mark (from the European Commission) is an assurance of minimising the risk of interference (eg.from Power Adapter) to the essential electronic systems in your car. Furthermore , manufacturer must obtain certification of consistent quality manufacturing practice and sysem as required by the e-Mark authority. However, the e-Mark only covers critical EMC spectrum and the CE provides further protection of electo-magnetic immunity. Safety always comes first, you do not want to end up with an DC car adapter that may affect your car's critical electronic systems , especially when you are on the express way. Look for other electrical safety features such as : a) Short circuit protection. b) Thermal cut off ( high temperature cut off). c) Overload cut off. d) Safety fuse at input. 2. Check if the user selectable output voltages covers your requirement and see if the types of plugs applicable to your portables. 3. Regulated (stable) output voltages Look for the word regulated, what it means is that the adapter will give a steady and stable output voltage even when input voltage from the cigarette plug or current taken by your portable fluctuates . This feature is essential for the proper operartion of voltage sensitive digital portables. 4. Sufficient Output Current The adapter must able to provide sufficient output current at the specific voltages of your portables, look carefully at the ratings of voltages and related output current. Most of the unregulated linear adapters give lesser output current at lower output voltages, for example, 500mA at 6VDC, 300mA at 3VDC. 5. Switching mode or linear DC Adapter Switching mode is the latest technology in power adapter. It provides the same max. Output current for all output voltages. It has a much higher efficiency of at least 80%. Therefore it wastes less power, and puts less strain on your car’s battery and alternator. Linear power adapter steps down the dc voltage by burning off excess voltage. Hence power is lost as heat in the adapter and available current becomes less as the output voltage steps down further. 6. Input voltages 12 VDC input is the norm as almost all family cars are of 12VDC. However; universal input voltages of 12-24 VDC may come in handy as trucks, caravan and other vehicles are of 24VDC. 7. Power cable and stopper (Strain Relief) construction Most plug in and pull out electronic devices' failure is due to the poor quality cable end stopper and cable . Earphone is a typical example. Look for an adapter with heavy duty , robust cable end stopper (Strain Relief) with min. 4 fins to safeguard possible loosening of electrical contact. Double insulation cable will withstand tear and wear better than single insulation. Cable length should be long enough (about 1.5M ) for use at the back seat. 8. Compact and fits all Make sure the adapter is small enough to fit in to the space around the cigarette lighter and in the glove box as well. Check carefully it contains the plugs for your portables in the assortment though you can buy the plugs elsewhere separately.
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