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Posts posted by explorador

  1. Hi, hope this is the right place to ask for advice.

    I use a GPS with my pocket pc via serial cable. It is a simple connection with only 3 cables. Now I moved to a Palm Tungsten T|X. By the documentation it seems the serial wiring is not that simple and not really a standard serial connection, risking my gps and my palm.

    So, Palms have a Infrared port.  It comes to my mind to send the serial signals form the GPS via serial-infrared. I found this  http://iguanaworks.net/ir/serial/ and the page states it is designed to work with THAT software... not like a standard serial to infrared.

    Is there any simple way one can convert the 3 cable connection to Irda? Its only involved the RX,  TX and Ground wires. No handshaking needed.

    I found some serial to IRda on the web but I don't know if they need all the pins to work (power and so). The GPS has only 4 pins, 3 are used to send data only.

    any advice?

  2. Sorry if this is not the right place... I totally don't know where to put this. It is a mixed idea and question as I'm no expert in this field., Ok, so:

    1. I have seen electrostatic generators claiming to generate lots of power (van de Graaf) The thing is this we can only get big sparks and stuff out of it. And electrostatic energy is still not useful in daily applications.

    2. If you connect the cables of the multimeter to a wire turned all over into circles, you got no power. But if you approach a magnet, it measures some volts... or minivolts. Ok, try the same with something chaged with electrostatic energy.

    3. I tried that and approaching something charged and the multimeter showed some minivolts...

    Any ideas in using a Van de Graaf and this method to convert that energy into something more coherent? sorry, it sounds stupid, but try it... I had to get out of doubts.

  3. Sometimes it is hard to find a nice and safe place to camp. I've been there... and while you need to rest, you pray to be aware when somebody or something is approaching to your tent in the wild. So I recalled this "burglar alarm" I saw on a electronic book years ago.

    Instead of using a battery infrared sensor (that only works in some directions) remember you need 360 coverage... Then,

    1. What about one of those noisy devices available at Radioshack as the alarm, they work with 1.5+ volts.
    2. Using a transistor as the switch to trigger the alarm.
    3. Use a long copper wire, that once broken, triggers the alarm

    This way, you could have the device in two pieces: The electronics, even the size of a watch and the replaceable wire.

    This how it will work:

    You go out, choose the place to camp. Then you put some sticks on the ground forming a triangle, or square, depending on your needs. Then, place the wire around the points and connect to the screw type connectors on the device. Turn it on (this way it could be inside your tent). The wire could be like the one found on motors, isolated.

    Once an animal or person brakes the wire, the alarm sounds. The maximum covered area its given on how much wire you use. It will be a tiny device, remember transformers and motors hold LOTS of wire inside.

    Any comments?

  4. Audioguru, Ante, Thanks guys!

    I tried with 4 diodes in series and, even that the multimeter reported 5.2+V, didn´t work to charge the PDA (it has a LED indicating "charing"...), I tired with less diodes and it worked, but didn't charge while using the PDA.

    So, I used only ONE diode and it works, both on and off, it charges the device with no problem. I'm still kinda confused as the multimeter reports even more volts than when using a universal charger (4V) and didn't turn on the thing.

    But anyway, now it is working. The only diode I'm using gets a little bit warm, so I will do what you say, putting a fuse to protect the system and a heat disipator to solve the heat thing and test it.

    Thanks a lot guys.

  5. Thanks. Sorry, I have found dif informations about this. Serious and reliable sources mention 6V as the maximum. Some users tested 7V with no problems (but there wasn't enough info for me to trust).

    I don't have the external adaptor (I found it on the web and it reported 5.9V), it is the model the catalog mentions (I don't have it), My PDA charges when is on the cradle. The PDA can be charged with several voltages, from 3.7 to 5 (what I tested), nothing more to avoid damaging it. Today I found a topic on the web stating 7 volts when charging but I don't want to take risks...

    The video camera battery is 6V NI CAD. Today I charged it (full) and the tester reported 6.9V. I don't really know about how many cells the battery have... :(

    Today I connected 4 diodes in series and it reported a drop from 6.9 to 5.8. Didn´t try it with the PDA as I'm still researching.

    audioguru, the mah is not like potency? at 5V, is it too much?

    Im kinda confused, as I tried another battery of 3.7 850mah to charge it, and it didn't last long... I understand, but as the voltage was getting lower and lower, the status indicator reported first "charging", then "AC".

  6. Hi, I'm new here and found a post (in this forum) about using diodes to reduce the current but couldn't understand it quite well as others suggested other ways and putting some capacitors on the system (  ???  )

    I have a PDA which uses an external folding keyboard. I use it to write when I travel (much better than a laptop). I also have a video camera battery (6.4V 2,700mah) that really lasts... so, I was thinking about using it as a external power source for my pda.

    The thing is the PDA maximum external power (without frying it) is 5V. So, 6.4/2,700mah would fry it right? I tested the diode thing, and 5 of them reduce the 6.4 to almost 5.1V, but I know there are more things involved than this... Would this work? I guess it could heat up the system and burn something.

    As far as I remember, volts and amps do matter... as is not the same as 5V with 850mah compared to 5V with 2A.

    There is an external adapter (AC to DC) for this model of PDA and it says 5.9V and 2.0 AMPS. Is it 2,700mah the same as 2.7A?

    I would apreciate any help, thanks

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