Latching on off circuit with momentary switch

[silviasol]

I have a gameboy advance that I did a backlight mod on.  There is a wire that I connect to 3.3v and it makes the screen brighter.  Removing the cables will put it in low brightness mod.  So I want to make a circuit that uses a momentary switch that will latch on/off due to space restrictions of installing a normal latching switch.  Is this possible with 3.3v?  I see many guides and dave made a video.

[Zero999]

It will work, as long as the MOSFET is a 3.3V logic level type but this circuit isn't what you need. It's designed to switch relatively high current loads, rather than a tiny logic signal. You need a flip-flop IC. To save space, you can buy single flip-flop ICs in SMT packages.

Check out the 74LVC1G74  and 74LVC1G175. Connect the D input to the Q output and CP to +V, via your switch, with a 100nF capacitor in parallel and a 100k pull-down to 0V and all other inputs to 0V. The Q signal will then toggle on and off, when the switch is pressed.
http://docs-europe.electrocomponents.com/webdocs/0b49/0900766b80b49d8b.pdf
https://assets.nexperia.com/documents/data-sheet/74LVC1G175.pdf

[silviasol]

Thanks alot for the advice.  I searched flip flop ic and found this for a few dollars.  http://www.ebay.com/itm/282381541189
I guess china has all the answers.

Next I have been researching using a lithium rechargeable battery with it.  There is a boost regulator to keep the voltage at 3.3v with the voltage range of the AA batteries.  I understand that a buck regulator is inefficient using along with the boost regulator so there is not much advantage with lithium ion.  I am wondering if I use a lifepo4 4/5AA size is it possible to regulate the power to 3.3v.  When it reaches the 3.3v which should be quickly, will the buck regulator still be drawing extra power making it inefficient?.