darkdestroyer

Will not work with regular batterys. Those batterys have a charge of 1.5, while the NIMH batterys have a voltage of 1.2. Therefore 4 series 1.2 = 4.8, the necessary charge needed to maintain and charge a Dell PDA.

Does anyone know the exact specifications of the Dell PDA Power requitements? Because the 9600mAh Li-Ion pack only supplys 3.6 V of power, not nearly enough for the Axim. I believe its ~5 v?

Tim L

I suspected that might be the case. Could a voltage regulator of some kind be used?

darkdestroyer

If it regulates the voltage at ~5V it would be great! I find that sometimes the power fluctuates a little when the batteries run low, so this regulator would be perfect.

Tim L

Originally Posted by darkdestroyer

If it regulates the voltage at ~5V it would be great! I find that sometimes the power fluctuates a little when the batteries run low, so this regulator would be perfect.

Reading around, it seems that using a 7805 voltage regulator with a 9V battery (or more AA cells) is the way to go. Apparently 6V isn't enough for the 7805 to properly regulate to 5V, although I need to read up on this properly when I have the time. I actually have a nice power supply with a variable voltage regulator in it that I built during my degree a long, long time ago, but I can't remember how much of it works these days. :(

In other news the PSU for the cradle claims to output 5.4 VDC - I've measured mine at 5.6VDC, which confirms for me that it has a voltage regulator so one is definitely required for a battery charger.

painethom

Positive or negative tip?

-=/>Thom

Snerkel

painethom ~ Positive tip for the X50 (most stuff is nowadays).

Tim_L ~ The LM7805 has a max current rating of 1A, not enough for the AX unless running processor in battery save mode with wireless switched off. Also the LM7805 would be a waste of power as it is a resistive device rather than the modern switching voltage regulators.

Tim L

Originally Posted by Snerkel

painethom ~ Positive tip for the X50 (most stuff is nowadays). Tim_L ~ The LM7805 has a max current rating of 1A, not enough for the AX unless running processor in battery save mode with wireless switched off. Also the LM7805 would be a waste of power as it is a resistive device rather than the modern switching voltage regulators.

Curses, foiled again!

Is there any sort of practical voltage regulation that would be appropriate for this application? I still find the idea being able to power the Axim from plain store-bought cells attractive for emergencies.

Snerkel

Originally Posted by Tim L

Curses, foiled again! Is there any sort of practical voltage regulation that would be appropriate for this application? I still find the idea being able to power the Axim from plain store-bought cells attractive for emergencies.

The problem tends to be that the circuits for the switch mode power supplies tend to be a little large if built using breadboard. darkdestroyer used what is a nice simple design that requires no regulation, and this is probably the way to go for a cheap easy to build system, however you do need charged NiMH batteries.

I am currently testing a power station (made for the Sony PSP) that is basically a battery pack with charging and voltage regulation circuit built-in (mentioned elsewhere on this site), it is very neat and so far is working very well (I am looping a movie to test running times). I will report on this soon, along with my mod to the unit to make it more universal for use with other devices.

darkdestroyer

This idea came to me right after I got home from BestBuy. I saw a PSP Charging brick and found out that it's charging pin fits right in with the Axim. Instead of paying 19.99 for a charging brick, i decided to make my own. And thus.... the 4x AA NiMh 2500mAh battery pack that is the same size as the PSP charger brick.

kevind

Has anyone tried these USB Power Packs? Appear to be a 4 AA cell pack with a USB female connector. You can use either of the USB charging cables.

EBay USB Power Pack

I've got a similar one coming to use my X50v on long plane trips.

zim2dive

Many other options exist for converting a 12V source to 5V (or 5.5V) (I used parts from TI)

http://zimmynet.com/bp/

Just to be safe, on my 3rd party sync/charge cable, I disconnected the +5 PWR feed, so it would only charge when power was off (via USB)).

Mike

yevgenie

Originally Posted by darkdestroyer

I wonder if anyone else would want one of these. I can get the parts from yard sales and makign them doesn't take much time at all. Is anyone else interested? I may sell these to people who want them.

How much do you think you would charge? I guess shipping might also add some cost. I live in Chicago.

darkdestroyer

I guess i'll charge maybe 10$ for this?
I'll have to find a source of AA battery holders and the male power jack. If you want it, i can sell it to you or guide you to some stores in your area.

lwalker

I have been making these for awhile starting with an iPaq 3600 in 2001 You can use regular batteries AA, AAA, C or D or a 6v lantern battery. (40000 Mah.) You need to use a cheap diode inline to reduce voltage to 4.8v.

yevgenie

Originally Posted by darkdestroyer

I guess i'll charge maybe 10$ for this? I'll have to find a source of AA battery holders and the male power jack. If you want it, i can sell it to you or guide you to some stores in your area.

In the old days, i.e. while I was an undergrad or in school, I would have just done it myself, but now I have trouble finding the time. I found out that Walmart carries the power bricks for the PSP for around $20.

(I'm not sure I will actually ever need it, but it would be nice to have the charger in my lab coat or instrument bag.)

I just got an email update from Dell. My x51v won't be delivered for another 2 or 3 weeks