I have a 2 inch Sony Watchman tv that runs on 4 AA batteries. I want to use it in the car during a trip this spring.
Is it better to buy a "power supply" that plugs into the cigarette lighter and generates 6 volts, OR
to run it with 4 batteries, measure the amperage, calculate the effective resistance of the TV, and then make my own power supply that plugs into the cigarette lighter, that would consist of a plug, a jack, a wire and a fixed resistor. The resistance of the resistor would be the same or nearly the same as the calculated different of the tv.
My experience is that fully charged AA batteries are usually 1.56 volts x 4 = 6.3 volts, which is exactly half of the resting voltage of fully charged car batteries, 12.6 volts. I won't be watching tv when the car is running, but maybe I would sometimes run the car to charge the car battery, or even to warm the car** Then, iirc and I can measure it to be sure, the voltage goes up as high as 13.2, half of which is 6.6. Also, the label on the back of the tv says that it uses, on average, 1.6 watts, but I will measure its current current use and not rely on that.
Is that too high for a tv that is meant to run on 6.3? If so, I'll be glad to make the resistor bigger and thus the voltage lower.
It also has provision for turning off the picture and only getting the sound. I guess it would use less current then and I would calculate a higher resistor to be needed. Maybe I should just use a resistor substitution box and see at what resistance the tv works best? Or should I buy a device made for this purpose. I have a spare cell phone charger, but I don't think it wil put out a full 1.6 watts.)
Thanks
**On my best car trip, I slept in the car for 7 or 8 nights in a row. It was very comfortable but it was a much bigger car, so I'm not sure I can do even one or two nights this time, but I want to get some use out of my 2 inch tv, which I got as a gift sort of, and which will be obsolete in 36 months or so. For tht reason alone, I'd like to sleep in the car rather than a motel. Or probably more likely, in a tent in a state park, in late winter or early spring, in the South, where I guess it will be warm enough. If I stay in a tent, I'll make a longer wire.
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