A very basic Cigarette to USB adapter.

[floodhound2]

A very basic Cigarette to USB adapter.

Skill Level – Beginner.

This tutorial will disclose all that you need to make a USB / cigarette adapter to charge anything that plugs into a computers USB port. My device is a Sansa 4 gig MP3 player. I can plug into the PC’s USB port for many things one being charging the battery. Lets get started.

Tools needed –

o Soldering Iron
o LM7805
o 1 - 10uF electrolytic capacitor
o Some type of case
o Cigarette lighter adaptor
o USB plug

First off you have to go and scavenge all the needed parts. Most of you geeks will have devices lying around that you can easily hack off the needed parts. For example I hacked a USB plug off of an old PCI card that had 4 ports on it. I did need to use solder wick to remove the solder, there are other ways for removing solder FYI. Next I found a cigarette lighter adapter for an old cell phone at the second hand store. I got 3 for $1.00, not bad. Then I robbed an old printer cable housing that I intend to use for the case. You can search for a LM7805 on old junk electronics boards as well as the capacitor, but I went ahead and purchased mine at Digikey. The rest is easy just connect as follows.

Here is my case and old computer printer connector.


Here is the cigarette lighter connector.


Here is a PCI card i can rob a USB connector off of


All together


And final look


A tight fit but crammed in


Schematic is here


Some things to keep in mind are the polarity of the input to the LM7805. To do this just plug in the cigarette lighter adapter and probe the 2 wires to find negative / positive using a volt meter. Then the podiatry of the USB port, remember the outer pins are for powering a USB device so make sure you probe them just to check that the device is wired correctly. That is all. I will post picture of the one I made for the long drive I have ahead of me. No more battery loss.

Just another basic device

[Big-E]

Hey floodhound - I have two questions.

First one is regarding this project.

Theoretically, I could take a female USB adapter and do the same thing and then take my USB Ipod charger and plug it in to charge it while on the road?

Just realised this it exactly what it is. My bad - should have read fully before I posted. ^^

Second question

How hard would it be to mod an old school keyboard into a wireless keyboard? I already have the old school keyboard and a wireless keyboard kicking around.

[floodhound2]

Hey floodhound - I have two questions.

First one is regarding this project.

Theoretically, I could take a female USB adapter and do the same thing and then take my USB Ipod charger and plug it in to charge it while on the road?

Second question

How hard would it be to mod an old school keyboard into a wireless keyboard? I already have the old school keyboard and a wireless keyboard kicking around.

Response to first question:

Assuming the ipod could plug into the Female cable i would say yes. When i get home Ill post pictures of this project and youll see that this would work on an ipod too.


Response to second question: Making the keyboard wireless would be effortless in my opinion, however the cost for the electronics might be pricey unless you make your own transmitter. Keyboard only uses 2 wires on the Ps2 plug

[Big-E]

Well, you see I have both the old keyboard and the new wireless keyboard that I don't like. I would much rather type on the old school kb with the big buttons. Screw this 'egronomical' bs.

[DNR]

One problem.
I use the USB port to connect and charge my V3 cellphone. The connection works as a dial-up modem.
I notice that my laptop battery is never really charged fully when I had the phone plugged in.
Using the V3 on my lappies battery power kills it quickly, and I mean like 20-30 minutes.
The power converter (that black box that is inline on the ac cord for the laptop) gets _very_ hot. I suspect that the output of 18.5 volts and 3.5a (amps?) is not enough for both the laptop battery and a external device (V3 motorola) According to the fine print on the OEM powercord, compaq says its to be used with only compaq devices, so they prolly won't repair/exchange a burnt out one, unless I lie.

DNR

[floodhound2]

One problem.
I use the USB port to connect and charge my V3 cellphone. The connection works as a dial-up modem.
I notice that my laptop battery is never really charged fully when I had the phone plugged in.
Using the V3 on my lappies battery power kills it quickly, and I mean like 20-30 minutes.
The power converter (that black box that is inline on the ac cord for the laptop) gets _very_ hot. I suspect that the output of 18.5 volts and 3.5a (amps?) is not enough for both the laptop battery and a external device (V3 motorola) According to the fine print on the OEM powercord, compaq says its to be used with only compaq devices, so they prolly won't repair/exchange a burnt out one, unless I lie.

DNR

I am not sure how this is a problem DNR

This simple device is used to charge a MP3 player or cell phone from a car battery. Your laptop needs a new battery as it seems so far. The power supply may also be under rated or faulting, either way charging a device (battery) is usually done with little amounts of current - keeps from blowing things up due to heat expanding etc. Of course charging may be accomplished by various methods, but the objective of driving current through the battery in the opposite direction of discharge remains impervious. True, It is necessary to consider the type of battery, the way in which the battery will be discharged, the time available for charge, the temperature extremes the battery will experience, and the number of cells in the battery (output voltage). It is important to consult the battery manufacturer at the time of purchase to determine the appropriate charging method.

In general, lead-acid batteries may be recharged at any rate that does not produce excessive gassing, overcharge, or high temperatures. Discharged batteries may be recharged at a high current initially. However, once the battery approaches its full charge the current must be decreased to reduce gassing and excessive overcharging.

A wide variety of schemes exist for charging batteries. - Reminder: is that the mp3 players and other portable devices have electronics sachems to charge properly incorporated already in them.

Thus the simple device above works well for charging and playing at the same time. take 12V squeeze it down to 5v @ 1amp max then let the MP3 player decide the battery's charge rate.

Hope this helps but ask more if needed.

[DNR]

I still believe that you will damage the power supply to the laptop. The 'weight' of the power needed to charge the battery and a external device could be taxing the power supply. I have seen this happen at other devices, AC/DC converters, computers with many devices plugged into the power supply, even automobiles with aftermarket car stereos - damaging the alternators and killing car batteries.

The devices could have an internal scheme for charging itself, but that is usually based on the assumption that it is the only device plugged in. The laptop battery ac cord w/power supply might be rated just for the laptop use, not necessarily intended for charging other devices. The power supply is rated at 18.5v, and the V3 phone charger says it puts out 5v, if the laptop is expecting 18v at least, but only gets 12v, something is going to hurt ...The laptop might control the battery charge, but it still asks for 18v..Then there is the issue of amperage, the phone wants 3.5a

Check out the usb dev specs
http://www.usb.org/developers/devclass_docs/



When I built rackmounts and desktop servers, we were always told never to use all of the plugs and slots - you never want to put the power supply at max output. Power supplies go bad in environments that have tough power requirements.
It is still a very plausible consideration when modding your computer.

DNR

[floodhound2]

I put up pictures i hope it clears up any questions

[DNR]

Got it, you were _not_ running through the laptop's/desktop's USB port for power - but the automobile's cigarette lighter was powering a device that uses a USB port for power.

I thought you had made a USB _HUB_ from a universal charger cut from a automobile cigarette lighter's cord and _then_ modded it to plug in to a laptop/PC's USB port.

Now, you still have to consider whether your mod meets USB 2.0 specs.
The spec talks about signals sent along the USB charger (a proper one) that controls the line output, your mod has the primary bus but nothing to handle the signals that the port and device transmit to each other. One case might be the need for inrush current limiting.

Also does that cigarette lighter filter the power supply from the vehicle's alternator (you know, when you install a cheap car radio - you hear a whine increase/decrease with engine rpm). That USB device may not be too happy with surges and spikes in its power supply.

Again, this is just a friendly technical discussion, somewhat clouded due the inherent nature of internet commo

Nice photos man.

DNR

[floodhound2]

Again, this is just a friendly technical discussion, somewhat clouded due the inherent nature of internet commo

DNR

For the record I do enjoy the discussion it would leave me pissed if no one questioned my tutorial. Thus said, thanks for asking about the project. Also i am more clear about your counter-post. You are correct, it is tricky to get sufficient power and make it work without damaging other circuits. The pictures helped a lot, sorry for the delay.

Now, you still have to consider whether your mod meets USB 2.0 specs.
The spec talks about signals sent along the USB charger (a proper one) that controls the line output, your mod has the primary bus but nothing to handle the signals that the port and device transmit to each other. One case might be the need for inrush current limiting.

DNR

As far as this design meeting USB2.0 specs, I am not sending data to the device so other pins on the USB connector are not necessary. I am only using the specific pins “as stated in the specs” for powering the device, or in this case; charging and powering it simultaneously. Consider the LM7805 as well. A nice 5V regulator to keep me well within spec's.

[DNR]

Let me also state for the record, floodhound does outclass me when it comes to hardware/circuits/nuts&bolts.

the 5v regulator probably takes all my worries away as the damn 1,000 page tec spec of the usb 2.0 kept telling me about signal wires D-, D+ that either increase or decrease the device's power drain.

I also see that you have the 10uF electrolytic capacitor, I assume you have this to filter out the noisy power supply from the automobile.

DNR

[Big-E]

Hey now, I am the nuts&bolts guy around here!

Speaking of which, Floodhound, if you ever need deals on machine screws you know who to come too. I don't plan on doing cross-border shipments but I suppose I can make some exceptions.

[floodhound2]

Thanks DNR, but where I outclass here - you make up in the other arenas of technology. This is what makes suck-o the shit!

The cap is used as a filter true and most of the time 2 should be used. This project I wanted to keep it simple and I used 1. A 10uF is good, but anything will work 47uF or 100uF to mention a few. For this project approximations will work.

As a side note if you take apart any digital device there is almost always a voltage regulator. They are easily spotted because of the capacitors placed right next to it. Take a look at the PCI picture



Note the 2 caps located on the top right corner. Right in the middle of the caps is a voltage regulator. It is a surface mount regulator and I could have used it but for noobs I wanted to use a 7805.

Also when looking at regulators reading the numbers will tell you what the voltage should be.

A 7805 means 5Volts
A 7812 means a 12Volt
A 7809 is a 9Volt
A 7905 is -5Volts
A 7912 is -12Volts

[Big-E]

I am going to have to take a picture of all the old boards, hardware and misc. machines kicking around my room and get some suggestions on something to build from you. Something to do when taking breaks from coding.

I want to build a robot, and program the AI for it. Think I can do it? ^^

Seriously though, I do have enough junk kicking around that something useful should be able to come of it. I will post a picture later if I get all the junk together in one shot. I am sure you could come up with some sort of suggestion.

[floodhound2]

Yes if you can stand it keep the old junk for hacks later. At times I have a lot of junk, but... WOMEN!