It has been a fun or frustrating dozens of hours lately (depending on how late in the night it gets). Buck converters are surprisingly simple in theory. (See http://www.maxim-ic.com/appnotes.cfm/appnote_number/2031/ and AN793 "Power Management in Portable Applications: Understanding the Buck Switchmode Power Converter" from www.microchip.com). I was going to use a 555 timer to generate the saw and a dual-741 opamp, (and other pasive components of course). I have them by the dozen, so its not a problem. I have been accumulating many parts over the years, which led me to review my data sheet folder.
I found this chip in my parts-box, which was labeled as PWM conrol (probably to control servos or so I thoght). There are two chips of interest: LM3075 (more versatile) and TL494 both bought at http://www.supremetronic.com/ - a Toronto store at Spadina and College.
With LM3075, I can generate the 3.3V efficiently and according to the maxim website 5V LDO is just fine. (Apropos, I am using a 7.2V 2400mAh battery, giving me a grand total of 14 hours of operation on the ground side!). Nevertheless, I think I will leave the Power section on the breadboard and do the other sections and experiment with better setups later.
0 comments:
Post a Comment