you will need the following things:
- the internet
- a web browser
- an "official" sounding email address. @hotmail or @gmail will not do (well actually it MIGHT but youre really reducing your chances). you need something like @stanford or @microsoft or something of that nature. i just use my university email account, @mcmaster. college will do just as fine. or get your parents to let you use their work address.
- a name
- a phone number
- an address
that list was mostly made up as a joke, conveying how easy it is to get these things. i slipped one important point in there though. guess which one
ok. so. we will be getting our dc-dc converters from texas instruments. feel free to look around their site:
www.ti.com
i would guess that 90% of people here need the dc-dc for their 3.3v line. (am i right when i assume the 12v doesent need a reg if you give it 7.6 off a battery pack?). so, i have done all the searching for you. the part you need is the PT78HT233H. (edit: in the months since i made this post, we have found better converters, check the wiki) the last letter can be several different things. it dosent really matter.
some features as listed at the site:
High Efficiency: Up to 90%
Wide Input Range
Self-Contained Inductor
Short-Circuit Protection
Over-Temperature Protection
Fast Transient Response
is your mouth watering yet? the product page and datasheet, respectively are
http://focus.ti.com/docs/prod/folders/p ... ht233.html
http://www-s.ti.com/sc/ds/pt78ht233.pdf
note that it requires at least 9v on the input side. (and is most efficient at that voltage too). if you cant make a 10 volt battery pack, then look for another product. they probably have it. they just might not offer free samples for it.
UPDATE: a lot of people are saying that these converters will run off 7.2v ok.
on the main product page, search around for a bit. you will come across a link that says "request free samples". see where this is going?
im assuming you have clicked it by now.
from there on in, you will have to make a new account. you will be sent a confrimation email, and then you will have to confirm your email...then you will be sent ANOTHER confirmation email. that part had me confused for like 10 minutes.
when you make your account, use REAL INFORMATION. this is a legitamate company. dont worry about spam or identity theft or anything.
i cant really guide you though this since i already did it. and i cant do it again. and i forget. but anyone smart enough to know how to hook up a dc-dc converter should be able to figure it out.
at the end of the day, you will have a "shopping cart" with the part you requested in it. you can only get one of these converters at a time, BUT, they come in 3 very similar "packages", and you can get one of each if you need to. while youre at it, browse their products for anything else that looks useful. they have more dc-dc's than you ever imagined, plus lots of other stuff.
BUT - dont abuse the system!!! dont order parts you dont need just because they are free. you WILL eventually be "cut off" if you start making tons of sample orders but never actaully buy anything.
when they ask you what shipping method you want, choose fed-ex priority... its FREE!
i ordered a dc-dc at 1:30 this afternoon, and according to my tracking number, it was shipped out by 1:45. im supposed to get it by 5pm TOMORROW.
and i live in <b>CANADA</b>
and that concludes the guide to free dc-dc.
but one more side note:
i have one of their dc-dc's right now that i got from school today. the only difference is that it is rated for 1 amp MAX. according to the guy who i talked to, this means it CANNOT outpute more than 1 amp. i have a 10 volt line hooked up to the 12 in the '64, and the dc-dc is hooked up to the same 10, and ouputting ~3.28. i have all the caps set up right, and even some more caps for good measure (two 100 micro electrolytics from 3.3 to ground, and a 47 micro ceramic from the 10 to ground).
when powered on, the light turns on, and the screen flickers repeatedly, as if it is trying to start but cant. could this be beacuse it just cant get by on 1 amp? ill tell you in a day or so i guess if the 2 amp model works.
oh well once they get here I should have all the parts to finish my unit.
