brownouts here in mindanao is quite often (at least once a week) due to the low power reserve (it's around 50MW for the whole mindanao island). although it does not last that long (average 1-2 hours), it's still is a problem especially at night. so it's important to have a lot of portable lights in the house ready for use during brownouts ...
one of our firefly portable lights gave up two weeks ago due to a spoiled battery (won't charge anymore). i went to Citi Hardware and Home Solutions Depot in marbel (new name is Koronadal) and could not find the exact battery model (FELB6/2.0 6V 2Ah) for the unit. they do sell a lot of 6V batteries (P350-P500 each) but they're all too big to fit inside the plastic case.
so, my problem then was how to use the portable light for now while i'm still looking where to find/buy the battery model for it? buying a big new 6V battery is pointless, as i won't have any use for it after i find the right model ... then i realize, i have 2 old 12V motorcycle batteries at home from my son's bike. i use it as a power source (when one is low bat, i just charge it and use the other one) for testing my HAS project ...
all that is needed is to convert 12V to 6V in a simple way so that i can use it for the portable light in case of a brownout ... solution use a single power regulator chip like the LM7806 to convert 12V to 6V ... problem solve, cost is just P18 for 1 piece of LM7806 at the electronics shop ... i do have a number of LM7805 (convert 12V to 5V) and i tried using it. the output light of the LED is not that bright compared to a 6V power source ...
the IC chip has 3 pins (Source (+), GND (-), Output (+)). connect the source and ground to the 12V battery source. then connect the output (+) to the 6V unit and the (-) of the unit to the GND of the IC chip also. it's that simple. if your going to use it for long hours, like 6+ hours or more, attach a heat sink to the IC chip to dissipate the heat generated by the IC ... photo below ... i could have use wires to make all the connection in the prototype board, but i prefer to solder it, to practise my soldering skills 🙂 he he he
Warning ... this setup is only a stop gap solution for temporary use, not advisable as a permanent solution. there are a lot of DC converter circuits in the internet that you can copy to make a simple and decent DC power converter based on your requirements ... cheers
Boo!
Well...................there are several factors to consider and not many can construct such a circuit and have it work well. It is much more efficient and trouble-free to use a BUCK switching power supply. However most of these are hugely over-rated; they say it can handle ...for example 5 Amps but really it can handle only 2 Amps/ And efficiency varies with the price; low price is low efficiency so your battery can not last as long as you thought it would.
