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Pocketbrain · 03-31-06, 11:52 AM

Build a +5V regulator dongle. It's easy.
Why? Let's say you have a 6V-12V AC/DC transformer that can push >1A of power (>=2A is best). Let's say you don't want to spend $20 or so for the Official charger (Dell's price online for the car charger), especially if you already have a couple of high-amp power adapters. The Axim likes a very steady ~4.8V-5.6V DC, so use of a regulator is required. I built this because I didn't want to have to drag my USB charge adapter to my car all the time, and I have a 2A auto power supply (set it to 6 or 7.5V).

Parts:

Supplies:

Heat sink grease.
Nuts & bolts (to attach the heat sink to the 7805)
Solder (I use lead-free)
Solder flux
AWG 20 or 22 Wire (I used 3 colors)
Clear nail polish (great to use for an electrical insulator to protect your open conductors and solder joints and reducing oxidation).

Tools:

Soldering iron/station
Needle nose pliers (bending wires, handling hot parts, etc)
Wire stripper

Techniques:

Measure, cut, and strip your wires before firing up the soldering iron!
If you mount the Reg/heat sink like I intend to, you have to trim the GND connector inside the socket, then drill the socket case.
Tin all wires before proceeding to attach them, then give the appropriate ones a 90-degree bend. I did that with 1 end each of supply and +5V leads. GND was looped around the GND connector of the regulator and passed to the plug.
Wiring: GND is connected from socket GND to regulator GND to plug GND. Supply voltage (+In) goes from socket +In(outside conductor) to supply (input) pin of regulator. +5V goes from the +5V output of the regulator to the +(outside conductor) of the plug. I selected wire colors: Black, Red, Green (GND, +In, +5V DC)

Schematic:

Some notes: the 7805 regulator is rated at 1A max, so you will need to include a heat sink if you want to push it past this limit. I wouldn't recommend recharging from a low battery with this regulator dongle, but I did the first time from 2% battery (stock 1100 mAH) and it turned out okay.
I used the RadioShack pieces linked above, except for the TO-220 heat sink. I had some of these lying around, so didn't have to spend $ on that part.

It's not finished! Well, it functions, but I have a couple of design adjustments to make. I had the screw attaching the heat sink going through the housing of the size M socket, but it contacted the ground connector, shorting it out: bad. I will have to desolder, trim the ground connector, cut the ground wire again, and resolder. Shouldn't take too long. Then the regulator/heat sink/socket will be one unit, and this will also relieve stress on the solder joints.

Apologies for picture quality: I took pix with my camera phone. Will update pix later.

First picture shows the assembly alone.

Second picture shows assembly with the Dell charge adapter for X50 series.

03-31-06, 11:52 AM	#26 (permalink)
Pocketbrain Aximsite Hall of Fame Join Date: Mar 2005 Location: West Palm Beach, FL Posts: 6,029 Device: iPhone Carrier: AT&T Thanked 0 Times in 0 Posts	Build a +5V regulator dongle. It's easy. Why? Let's say you have a 6V-12V AC/DC transformer that can push >1A of power (>=2A is best). Let's say you don't want to spend $20 or so for the Official charger (Dell's price online for the car charger), especially if you already have a couple of high-amp power adapters. The Axim likes a very steady ~4.8V-5.6V DC, so use of a regulator is required. I built this because I didn't want to have to drag my USB charge adapter to my car all the time, and I have a 2A auto power supply (set it to 6 or 7.5V). Parts: +5V Fixed-Voltage Regulator 7805 4.0x1.7mm Coaxial DC Power Plug Size M Coaxial DC Power Plug TO-220 Heat Sink Supplies: Heat sink grease. Nuts & bolts (to attach the heat sink to the 7805) Solder (I use lead-free) Solder flux AWG 20 or 22 Wire (I used 3 colors) Clear nail polish (great to use for an electrical insulator to protect your open conductors and solder joints and reducing oxidation). Tools: Soldering iron/station Needle nose pliers (bending wires, handling hot parts, etc) Wire stripper Techniques: Measure, cut, and strip your wires before firing up the soldering iron! If you mount the Reg/heat sink like I intend to, you have to trim the GND connector inside the socket, then drill the socket case. Tin all wires before proceeding to attach them, then give the appropriate ones a 90-degree bend. I did that with 1 end each of supply and +5V leads. GND was looped around the GND connector of the regulator and passed to the plug. Wiring: GND is connected from socket GND to regulator GND to plug GND. Supply voltage (+In) goes from socket +In(outside conductor) to supply (input) pin of regulator. +5V goes from the +5V output of the regulator to the +(outside conductor) of the plug. I selected wire colors: Black, Red, Green (GND, +In, +5V DC) Schematic: Some notes: the 7805 regulator is rated at 1A max, so you will need to include a heat sink if you want to push it past this limit. I wouldn't recommend recharging from a low battery with this regulator dongle, but I did the first time from 2% battery (stock 1100 mAH) and it turned out okay. I used the RadioShack pieces linked above, except for the TO-220 heat sink. I had some of these lying around, so didn't have to spend $ on that part. It's not finished! Well, it functions, but I have a couple of design adjustments to make. I had the screw attaching the heat sink going through the housing of the size M socket, but it contacted the ground connector, shorting it out: bad. I will have to desolder, trim the ground connector, cut the ground wire again, and resolder. Shouldn't take too long. Then the regulator/heat sink/socket will be one unit, and this will also relieve stress on the solder joints. Apologies for picture quality: I took pix with my camera phone. Will update pix later. First picture shows the assembly alone. Second picture shows assembly with the Dell charge adapter for X50 series. Last edited by PocketBrain; 06-06-06 at 01:34 PM.