NimH AAA to 5V, suggestions?
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From: Grant on 4 Aug 2010 01:57 On Tue, 03 Aug 2010 20:30:02 -0400, Rich Webb <bbew.ar(a)mapson.nozirev.ten> wrote: >On Wed, 04 Aug 2010 08:42:44 +1000, Grant <omg(a)grrr.id.au> wrote: > >>On Tue, 03 Aug 2010 12:26:49 -0400, Rich Webb <bbew.ar(a)mapson.nozirev.ten> wrote: >> >>>On Tue, 03 Aug 2010 18:47:15 +1000, Grant <omg(a)grrr.id.au> wrote: >>> >>>>OT: Does Agent have a line rewrap function? I can't find it, >>>>would save me propagating Tim's endless lines when I'm too lazy >>>>to manually reformat (no I don't mean the line length setting, >>>>I need to break that sometimes too). >>> >>>From the menu, View | Word Wrap, or just press the "O" key to toggle >>>between wrapped and as-sent. >> >>Thanks, I know of that one. I forgot to say I was after a line >>rewrap function for use while composing a reply, to rewrap the OP's >>post. Some user agents have that feature, but I can't find it on >>Agent. >> >>Sometimes I'll rewrap manually, but it's messy putting in the '> ' >>in front of each new line. Or, I could rewrap a line, then cut >>the block and paste as quoted to get the '> ' fitted. >> >>Is there an easy quicker way to do that in Agent? > >Hmm... The obvious way of Ctrl-C copying the source text and then "paste >as quote" seems to keep the original line lengths. Rats. > >The only clean way seems to be getting the original text into a editor, >reformatting then copying from there and pasting back into Agent. I'll stay with add newlines, then cut paste as quote to get the '>', when it occurs to me ;) Grant.
From: Jan Panteltje on 4 Aug 2010 12:31 On a sunny day (Wed, 04 Aug 2010 10:08:30 +1000) it happened Grant <omg(a)grrr.id.au> wrote in <uobh56phejv8fgbc92k72n10fn8c9v53se(a)4ax.com>: >>Yes, this is the filter that IIRC was around the cable of an old keyboard (inside the keyboard). >>Most cores I try just work, a smaller one than this should work here too, >>but I have used all thsoe. >>Time is expert on magnetics, you do need a bit of permeability, else >>you need so many turns. > >It's good to see something useful with so few turns. I tend to use >storebought inductors so I know what value I'm dealing with, which is >good for getting a switcher going easily. Not the cheapest way. > >Grant. Here is a test with a 'store bought' inductor, well, I took it from some old PCB, ftp://panteltje.com/pub/1.2_to_5V_converter_img_2252.jpg This is that coil in detail, I added a 5 turns secondary for feedback :-) Also changed the diode for a smaller Schottky. The effect is that the frequency drops a lot, and efficiency goes up a bit. I measure this: In 90 mA at 1.222 V -> 0.10998 W Out 13.87 mA at 5.53 V -> 0.07670 W This gives an efficiency of 69.74 %. The frequency is 37 kHz. With a 2300 mA NiMH rechargeable the thing will work for 25.55 hours exactly. I am satisfied, It should also work with high efficiency LEDs or LEDs that drop close to 3 V. That is why I use a 5V supply, and not 3.3. I forgot to measure this inductor, in fact I should also design an inductance meter, but it could be as much as 160 uH, if they followed the application note in the thing I took it from. (A L4962A based switcher), but it could be far less. An efficiency of say 70 % does not seem much, but is difficult to improve at 1.2V, due to the Vce sat of the transistor I think. Maybe things could be tweaked a bit to 75 %, but likely not much more.
From: Jan Panteltje on 4 Aug 2010 12:42 On a sunny day (Wed, 04 Aug 2010 16:31:50 GMT) it happened Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote in <i3c4lv$1uh$1(a)news.albasani.net>: >This is that coil in detail, I added a 5 turns secondary for feedback :-) Forgot lthe link: ftp://panteltje.com/pub/1.2_to_5V_converter_coil_detail_img_2256.jpg
From: Jan Panteltje on 4 Aug 2010 15:23 On Aug 2, 6:09 pm, "IanM" <nos...(a)nospam.co.uk> wrote: > I know there are little chips for 1.2 to 5V or 3.3V, > > what is a good jellybean one? > > Preferably one I can see with the naked eye and can buy in Europe :-) > > Have a look at Sipex SP6641A - I used it with 2 cells, but it is > specced to 0.9 volts Nice chip, MOS switch, abd that at such a low voltage. It sure is smaller then the discrete circuit I have now, Efficiency seems about the same for the A and a bit better for the B version. For sure something to keep in mind if this ever becomes a big series.
From: Grant on 4 Aug 2010 18:20
On Wed, 04 Aug 2010 16:42:27 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Wed, 04 Aug 2010 16:31:50 GMT) it happened Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote in <i3c4lv$1uh$1(a)news.albasani.net>: > >>This is that coil in detail, I added a 5 turns secondary for feedback :-) >Forgot lthe link: > ftp://panteltje.com/pub/1.2_to_5V_converter_coil_detail_img_2256.jpg Yes, I saved a few of that style from dismantling old gear. Grant. |