New poster, seasoned technician.
Im designing a dc system in my apartment (half of which is more of a workshop then an apartment) to automate and interface sevral appliances lights, and security features. Mostly for my own amusement but also as some good advertising to get some custom projects. For now i am actually using a 12 volt deep cycle boat/ RV battery to allow for larger currents than i have ben able to draw from a few AC to DC power sources i have built. I figured it was better to make a 500mA "trickle" charger for sevral reasons. so my question is i want to eliminate the possibility of a large draw on the battery over loading my charger, or the 120v power in my apt. If wired directly with only one battery my logic says i need to design a circuit to automaticly disconnect the charger positive wire when current exceeds a certin value. Ive drawn out a schematic where voltage drop is read across a small value "sense" resister in series with the positive charger wire. This value i want to direct to one input of a op comparitor, and a supply voltage with a variable resister for calibration to the other input. The comparitor output would then feed the base of a transister, which would drive a NC relay that would open the charging circuit until the current fell. Anyone seen any similar circuits i could refrence? an other input would be helpfull too, thanks