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Why not use a 9V battery? When you can get them easily?
Doubt the LM2731 is obsolete. I think we brought it out around 2007. It was making a TON of money doing the LED backlight apps for PDA devices. I'll bet Digi-key has it.Great bounty and ronv, i appreciate your reply, looks like the Lm3721 is gud idea, but i don't know whether it's obsolete or will be available here
@ziddik/anyone, you dint reply to my legitimate question: #34
Hi James,9V battery will drain quickly if i used it for a Tx, that is why
Yes.Do you mean it because they have low mAh rating?
Yes.
Look at the datasheet of a 9V alkaline battery on the website of its manufacturer. It lasts long if its load is only a few mA.
My FM transmitter draws 53mA and after 2.5 hours the brand new 9V alkaline battery is down to only 7V and the range of nthe transmitter is reduced a lot.
You might try calling National Semiconductor directly, ask for the Applications group for Power management. They had an 800 number. Here is the secret:No.heck, sometimes i start hating this country
I would use three Lithium cells in series. I believe the Li MnO2 (lithium manganese dioxide) types have a full (new) voltage of 3.3V. I doubt you need to use a 9V regulator.That answers my ques. I would also suggest to use a series combination of 3V(or 3.7V in above case) to get 9V. That would also work, but perhaps we need to again use a 7809 to get a stable 9V output.
A few years ago, in your country, Silicon Chip magazine published three 1.5V then 3V to 9V converter projects using ICs from Texas Instruments. One converter IC is the TL499.No.heck, sometimes i start hating this country