Emulate AAA Batteries for my logger

[LaN-]

Heres the story

i got a Palm m100 for my logger running MMCD it takes 2 AAA batteries. I was wondering if anyone has or has ideas for how i could hard wire this to the car, basically take a 12 volt connection make a small circut board to get it to the specs the Palm needs then hook it back up to the palm.

and I'm not the best with electronics so anyone got ideas on how to get a small circut board together

I think i might need to 2 different power soruces because when i shut the car off and the hard wire is now dead it still needs a small charge to hold the info on the Palm, mabye i could put the batteries in it and somehow have it switch over when it needs to????

 

[poppyseed]

use an Lm317 I am not explaining anything more its all in the data sheet which i also provided below. The simplest design would be to use 1 resistor and one small potentiometer to fine tune the voltage. Then glue it to that position.

http://www.national.com/ds.cgi/LM/LM117.pdf

For those of you who are terribly afraid to make anything. You can go to a local radio shack and by a universal car adapter for the cigarette lighter with various setting choose the voltage of the device you have, crack open the part that goes to the cigarette lighter tap the wires into the what ever you want always hot (possible battery drain problems) or ignition hot to switch on and off. If I am not mistaken radio shack should already have a palm pilot (no palm specs needed already done) car adapter for your cigarette lighter. All you have to do is attach a wire to the nipple of it and then to a power source and the side of it goes to a chassis ground. Soldering is a good way of doing this.

Then you can hide the power adapter under the center console or under the radio in that area because it would be easiest to tap power off the switched power to the radio, or from a remote line.

Any more pimp my ride inventions

Next week how to put a microwave in your DSM now thats something nobody has done

 

[96whgsx]

When you turn the car off, wouldnt the power shut off, losing all your memory on the palm?

 

[poppyseed]

When you turn the car off, wouldnt the power shut off, losing all your memory on the palm?

If you wire it to a constant hot no.

Plus you may have to add some data lines or splice into data lines to the connector that is already there for the palm. Have good batteries in your palm for when you unplug it.

 

[Defiant]

Next week how to put a microwave in your DSM now thats something nobody has done

Behind the grille, to touch-off handheld radar guns.

 

[LaN-]

i was concern about losing the data when the power shuts off which is why i was thinking of it somehow switching over to the batteries that are inside the palm when it loses the power from the battery

 

[poppyseed]

if the palm won't switch over like a normal cell phone will with a charger, then you can do this with a wood dowel (diameter close to AAA then use tape instead of batter cover to hold it in) or even soldering wires to the palm directly then to the battery. each spot will need its own battery because i am not sure how they have the batteries wired in the device.

Basically all you are doing is using really big batteries that won't fit (since they don't fit you need to use wires to hook them up) in the palm because they are the same voltage, since they don't fit you need to use wires to hook them up.

You can bunch stripped wire up and duct tape it to the battery. remember to get the polarities right. basically wire with nipple goes to same place nipple of AAA goes.

a few D cells and that palm should last for weeks if not months before you have to change the batteries

Defiant i am not sure what you are getting at with radar detector and microwaves. They are totally different frequencies, and won't interfere with each other, so what you are trying to get at i think is that the radar detector will pick up the microwaves. It doesn't work like that. The frequencies are so far apart that won't happen because of the band pass filters in the radar detectors and the spectrum of the radar detector's sensor.
If you stick a radar detector in the microwave something may happen because you are saturating it with energy.

 

[LaserCool]

if the palm won't switch over like a normal cell phone will with a charger, then you can do this with a wood dowel (diameter close to AAA then use tape instead of batter cover to hold it in) or even soldering wires to the palm directly then to the battery. each spot will need its own battery because i am not sure how they have the batteries wired in the device.

Basically all you are doing is using really big batteries that won't fit (since they don't fit you need to use wires to hook them up) in the palm because they are the same voltage, since they don't fit you need to use wires to hook them up.

You can bunch stripped wire up and duct tape it to the battery. remember to get the polarities right. basically wire with nipple goes to same place nipple of AAA goes.

a few D cells and that palm should last for weeks if not months before you have to change the batteries

I would caution you that a single D cell or AAA cell produces 1.5V, 2 produce 3V. There seem to be a couple of ways to skin this cat.

I'd use either a fairly good size resistor, and take advantage of both voltage drop and current limiting so the Palm doesn't get too much power. or use a voltage limiter LM series (as mentioned above ) along with a resistor for current limiting.

Offhand, I don't know how many amps a AAA battery produces, but I think it'd be in the low mA range. This is close to the drain of the ECU and TCU in the car already, running off the car battery, so a properly limited connection to the car battery would allow you to keep the Palm in the car indefinitely.

Defiant i am not sure what you are getting at with radar detector and microwaves. They are totally different frequencies, and won't interfere with each other, so what you are trying to get at i think is that the radar detector will pick up the microwaves. It doesn't work like that. The frequencies are so far apart that won't happen because of the band pass filter in the radar detectors

Another fine forum I'm on - http://www.radardetector.net/

 

[poppyseed]

I would caution you that a single D cell or AAA cell produces 1.5V, 2 produce 3V. There seem to be a couple of ways to skin this cat.


2D cell will produce 3V to, but since we don't know how the batteries are wired in the device because they could be tapped for 1.5V and 3V, better off sticking with the idea with the pic. Is it clear how to do that now

you didn't read what i wrote above. D cell are 1.5V, 1 D cell replaces one AAA so you will need more than one D cell or to make it clearer for you 1 drawing i have up there for each battery in the device

also you mention current, current from the battery is dependent on the device not what is supplying the power. mAh is the life rating of the battery AAA has next to nothing for that, and D cell will probably have lets say 100 times that if not more, which means the device operating would last 100 times longer. when using the lm regulator you don't need a current limiting resistor its not that type of device(plus it is current limited with thermal shutdown). You would use a capacitor to help filter the DC out of the regulator, once again current draw depends on the load not the supply, at most you would want to use an inline fuse the glass tube (incase you short something) kind with a value as close as you can get to the devices rated current with out going below and with out it burning up when you turn the device on.


and no you cannot just make a divider network with resistors, because of loading caused by the palm pilot. Since it has voltage regulators you may be able to do it, but I wouldn't, it is to risky to debate whether or not you will be in spec for the regultors after a load is applied. My dumbass did that one time with out thinking it through first for something else.



radar just barely meets microwave cut off so i would call that cheating. and then it would be possible for cheap radar detectors to pick this up for the few gigahertz, the spectrum over laps at the bottom for microwave and radar, i thought it was more clean cut.

 

[poppyseed]

Thats how to do it with for 3V out or 1.5V out

with 1.5V i am not sure if it will stay in regulation i may need to lower the 240ohm resistor to 120ohm so i can pass close to 10mA for the sense of the regulator, which would then need the bottom resistor to be 24ohms in order to get 1.5V, also a heat sink maybe need cuase it could hit thermal shutdown.


The resistor value of the bottom you want to use a potentiometer because different regulators are going to need different types of fine tuning (the values i gave you will get you really close but you always need to fine tune because of tolerances of the resistors and regulators). If you buy ones that are made at completely different times then there tolerances are going to be different.

Most likely you are going to need a heat sink because you are dropping around 10.5V across the regulator. At 400mA thats 4.2 watts hope the palm doesn't use a lot of current or else you will need a pretty big heat sink.

if you add a resistor (high wattage) in series with the voltage regulator (before the regulator)
to help reduce the power dissipation of the regulator. you will need to play around with the 2 resistors to get the correct voltage out while a load is attached to the output (preferably not your palm). This way you would need a smaller heat sink

 

[poppyseed]

better yet is there a, dc in plug (like old cell phone style plugs or laptop power plugs the shiny tube), on the palm you have, or is it a special adapter that can tranfers data like new cell phones

 

[LaserCool]

2D cell will produce 3V to, but since we don't know how the batteries are wired in the device because they could be tapped for 1.5V and 3V, better off sticking with the idea with the pic. Is it clear how to do that now

you didn't read what i wrote above. D cell are 1.5V, 1 D cell replaces one AAA so you will need more than one D cell or to make it clearer for you 1 drawing i have up there for each battery in the device

Again, it depends on the requirements of the Palm. Since resistors limit current but not voltage (but consequently limit total power), it might be possible that one configuration works over another configuration.

I simply don't know enough about the Palm to compitently answer that question without researching it.

also you mention current, current from the battery is dependent on the device not what is supplying the power. mAh is the life rating of the battery AAA has next to nothing for that, and D cell will probably have lets say 100 times that if not more, which means the device operating would last 100 times longer. when using the lm regulator you don't need a current limiting resistor its not that type of device. You would use a capacitor to help filter the DC out of the regulator, once again current draw depends on the load not the supply, at most you would want to use an inline fuse the glass tube (incase you short something) kind with a value as close as you can get to the devices rated current with out going below and with out it burning up when you turn the device on.

I have used LM series voltage regulators, but with a sensitive device like a Palm, I'd current limit the output of a car battery prior to the LM, so that the LM doesn't have to work as hard and as futher protection for the Palm.

But as I said, there's more than one way to skin this cat.

and no you cannot just make a divider network with resistors, because of loading caused by the palm pilot. Since it has voltage regulators you may be able to do it, but I wouldn't, it is to risky to debate whether or not you will be in spec for the regultors after a load is applied. My dumbass did that one time with out thinking it through first for something else.

Um, I don't recall mentioning a divider network, unless you're throwing that out to someone else...

 

[poppyseed]

Again, it depends on the requirements of the Palm. Since resistors limit current but not voltage (but consequently limit total power), it might be possible that one configuration works over another configuration.

In this case you cannot use a resistor to limit current, thats now how the equations work. A high wattage resistor could be placed before the regulator ( to help dissipate power and drop voltage so that less voltage is dropped over the regulator), with the regulator loaded, next i would take measurements and adjust the pot to figure what resistors are need and i am not calculating that from scratch with out taking measurements because every thing just got way more complex and measurements would easily simplify it back to what it was before.

I simply don't know enough about the Palm to compitently answer that question without researching it.

and i doubt we ever will because i am sure that info is pretty close to top secret from palm

I have used LM series voltage regulators, but with a sensitive device like a Palm, I'd current limit the output of a car battery prior to the LM, so that the LM doesn't have to work as hard and as futher protection for the Palm.

Then you should know that they are very good regulators, and that you cannot use a resistor for current limiting in this application, to current limit this you would need transistors. This is not a current limiting resistor application. Resistor blocks for injectors is one to do that for, also to lower the current through a relay so it doesn't get as hot on the coil side and draws less power to keep the relay active thats what current limiting resistors are for not this,

But as I said, there's more than one way to skin this cat.



Um, I don't recall mentioning a divider network, unless you're throwing that out to someone else...

You started saying things like big resistor, was not clearly stated

Also current is a function of voltage and resistance, so saying that resistors restrict current is not totally correct, i don't care what book says other wise.