Hi.
Not so long ago I designed a little project that involves a car stereo and a PC PS and a battery (8x AA battery to give 12v). The battery is there to keep the presets in the radio, however when left over for longer period of time they will drain as there is very lil amp hours on them. I had an idea of either bulding a battery charger that will trigger when the batteries are low, or resigning from the batteries to some old wall wart that gives 12v. The wall wart solution will be more convenient, but I have some doubts about it:
The wall warts are usually rated for amps (mA usually), and I remember blowing some old gadgets when I was lil using a wrong power supply, since I am not sure how much current the radio needs to keep the presets and I dont know how much it can handle (blowing the radio will really make me sad as it costs a lot- nice quality deck). So my idea was to measure the current flowing through the positive terminal of the batteries when the radio is off (radio will drain some small current i assume to keep the settings) using a multimeter and then trying to find a corresponding wall wart- is this a correct approach? Can I accurately measure the current this way? and I want to be 100% sure this wont hurt my radio.
Any help and suggestions will be greatly appreciated. thanks
Not so long ago I designed a little project that involves a car stereo and a PC PS and a battery (8x AA battery to give 12v). The battery is there to keep the presets in the radio, however when left over for longer period of time they will drain as there is very lil amp hours on them. I had an idea of either bulding a battery charger that will trigger when the batteries are low, or resigning from the batteries to some old wall wart that gives 12v. The wall wart solution will be more convenient, but I have some doubts about it:
The wall warts are usually rated for amps (mA usually), and I remember blowing some old gadgets when I was lil using a wrong power supply, since I am not sure how much current the radio needs to keep the presets and I dont know how much it can handle (blowing the radio will really make me sad as it costs a lot- nice quality deck). So my idea was to measure the current flowing through the positive terminal of the batteries when the radio is off (radio will drain some small current i assume to keep the settings) using a multimeter and then trying to find a corresponding wall wart- is this a correct approach? Can I accurately measure the current this way? and I want to be 100% sure this wont hurt my radio.
Any help and suggestions will be greatly appreciated. thanks