$1 USB Car Charger From 3 Parts




You would like to travel on car, but you haven't charger for your phone/navigator/camera? With my instructable you can make it very easy. You need only 3 parts, that you can buy for $1!

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Step 1: Parts

1. Box from old charger (I use box from old siemens charger).
2. Radiator or metal plate ( Link)

3. USB port (Link)

4. Voltage Regulator LM7805 or L7805CV or L7805 (Link).

5. Сapacitor 0.33 μF
6. Сapacitor 0.1 μF
You can not use capacitors, but i highly recommend to use it.

Step 2: Whats Need

1. Soldering-iron.
2. Some wires.
3. Glue gun or another glue.

Step 3: Voltage Regulator

At first you need to solder wires to voltage regulator and isolate it.

Step 4: Connect Voltage Regulator

Connect Input wire via capacitor (0.33) to gnd. After connect Output wire via capacitor (0.1) to gnd. Connect Input to "+" of box and connect gnd to "-" of box.

Step 5: Connect USB

Now you need to connect USB port. Connect GND to GND and 5V to Output pin on Voltage Regulator.

Step 6: Test It

To test you can use multimeter or any usb tester.

Step 7: Plase All in Box

You need to cut a hole in the top of box and plase all to box. After you need to glue USB port

Step 8: P.S.

Thank you for reading my instructable. I try to make instructable very short becouse i don't know english well. If I made a few mistakes, please forgive me)

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    5 Discussions


    3 years ago

    That setup will get over 125C if you draw about 200mA. 7805 has a theta of around 65C rise per watt dissipated. You will have 7-9V drop (14V to 5V). The voltage drop times the current is the power dissipated in the regulator. That power times the theta value is the temperature rise of the part. The plastic used in that adapter is probably only hard to about 100C. At 200mA this will melt the plastic and probably short the whole circuit out in the lighter socket. Please be careful with this and monitor it closely.

    2 replies

    Reply 3 years ago

    If you will use good radiator it be around 50C°-70C°.


    Reply 3 years ago

    Depending on your part supplier, the LM7805 can have a Theta of 19 or 65 C/W. That is a huge difference. So I reran the calculations. At 200mA with Theta = 19 C/W you will hit about 60C max. I also ran the calculations at 500mA and put them in an attached image to show others how to do them. It looks like if you have a TI part you will probably be OK but still running really hot. I'm still concerned that since there is no air flow over the package it will heat up past the melting point of the plastic.

    Keep plugging away!

    Lm7805 power_0(1).jpg