Anyone reliable know how to make a nice USB sensor bar?

moccor · 08-21-2013, 11:47 AM #1

Hi, I would like to make a sensor bar using IR LED's, but I don't want to use batteries. Does anyone have a reliable guide/info on how to make this? I Googled and found some, but I really don't want to plug something into my PC and screw it up. And I do know how to solder, but it's been a while since I learned about all that Ohm and Amp stuff, that's why I asked here for reliable info. Any help is appreciated, thanks.

**ulao** · 08-22-2013, 08:17 AM #2

I created 6 or 7 of them out of the Nintendo brands. All seem to be crap in the end. It really comes down to your house lighting. If you are in a small room with 1 or 2 windows then the usb bar off ebay works fine. If you are in a big room with > 3 windows I find they suck. If you are more then 6 feet form the bar I also find they suck. The problem is for the most part making your own may work. Most people do this and post there workings. What they dont do is post how they fail after 6 months. So there is no real "good" post out there as no one follows up. Maybe someone that has had good success will chime in here.

moccor · 08-22-2013, 08:45 AM #3

(08-22-2013, 08:17 AM)ulao Wrote: I created 6 or 7 of them out of the Nintendo brands. All seem to be crap in the end. It really comes down to your house lighting. If you are in a small room with 1 or 2 windows then the usb bar off ebay works fine. If you are in a big room with > 3 windows I find they suck. If you are more then 6 feet form the bar I also find they suck. The problem is for the most part making your own may work. Most people do this and post there workings. What they dont do is post how they fail after 6 months. So there is no real "good" post out there as no one follows up. Maybe someone that has had good success will chime in here.

Thanks for the info. Well if Nintendo's bar works, then a homemade bar with the equivalent number of IR LED should work in the same setting right? Or are their IR LED much higher quality? And not that I doubt your knowledge, but you mention how nobody posts that they fail after 6 months, but how do you know that if nobody posts it Tongue

? I just figured a homemade sensor bar done right would work better than some cheap overpriced one

**ulao** · (This post was last modified: 08-22-2013, 10:25 AM by ulao.)

Quote:how do you know that if nobody posts it

Ok fair enough, because I'm an electric engineer. Because the source of power is not truly divisible by 4.7( usb voltage) for each IF-LED. Because the actual schematic to do it right I post last year ( god knows where it is ) is the proper way to do it without long term damage ( no one ever tried it that I know of ). And most importantly the voltage can change and is not clean. You would need a regulator to do it right.

Quote:Well if Nintendo's bar works, then a homemade bar with the equivalent number of IR LED should work in the same setting right?

Not sure what makes you think that? A usb puts out 4.7-ush volts and is not steady, especially if you have more devices on it. The Nintendo puts out 7 something I think ( been a long time since I have looked it up). Most people think its 12 or 9 and that is way wrong.

Quote:I just figured a homemade sensor bar done right would work better than some cheap overpriced one

LOL, why? A home made is made by someone with little knowledge for the most part in the matter at hand. If some random companie makes one they better at-least make it work. True, that is not always the case but I would prefer it to a home made version any day of the week. As I said I tried a few methods. The usb version I made worked but was way to week ( I posted the schematic somewhere o this board) and discarded it for that reason. So I instead tried to power a Nintendo bar with my own voltage regulator using a power supply. I was very happy with the brightness I could achieve but never found the right steady voltage from a power supply laying about the house. If I were to do it again I would get the actuate voltage form a unit along with the drawing current and buy a power supply that handles a bit more volts and regulate it with a proper regulator. Its just not anything I'm interested in as I like my wireless battery eater at the moment.

ok here was the post POST 7 ( mind you this is regulated 5v )
https://forums.dolphin-emu.org/Thread-us...sensor-bar
but it may be too technical for some.

**AnyOldName3** · (This post was last modified: 08-22-2013, 10:17 AM by AnyOldName3.)

I bought:

The cheapest Wii bar on Amazon.
The cheapest USB cable on Amazon.

I plugged the Wii bar into my Wii, and measured the voltage across each bank of LEDs and the voltage across the resistors with a multimeter. Also, I used the coloured rings on the old resistors to work out their resistance.

Bearing in mind that the output voltage of USB 2.0 is 5V, I used Ohm's law, the resistors in parallel equation and a piece of paper to work out the resistance of the LEDs, and therefore what resistance would be required to mean the LEDs had the same voltage across them.

I realised I had no 10 Ohm resistors, because 10 Ohm resistors are practically useless.

I realised a diode would cause the same voltage drop as I needed, so swapped the pair of resistors with a pair of diodes, and soldered the positive and negative power lines in the USB cable to where the power lead originally attached to the bar.

I plugged it in, and tested everything was as bright as it should be. It wasn't even on on one side.

I removed one diode, and put it in the other way around.

I plugged it in, and tested everything was as bright as it should be. It was.

I then cut a neat hole for the fatter USB lead to leave the sensor bar through, and then screwed it shut.

Thankfully, I decided to derive you a formula which should tell you what value resistors you'll need.

Rnew is the value of the resistance of the resistors you'll have to buy in Ohms.
Rold is the value of the resistance of the existing resistors which you found out from the coloured bands printed onto them in Ohms.
VLED is the value of the voltage across the LEDs in the Wii bar when you plug it into a Wii, which you measured with a voltmeter/multimeter in Volts.
Vold is the value of the voltage across the resistors in the Wii bar when you plug it into a Wii, which you measured with a voltmeter/multimeter in Volts.
5 is the number of volts USB outputs in Volts. If you feel less than confident about my memory, feel free to use a multimeter to test the voltage output of the USB port you're going to plug this into.

The equation:

Rnew = ( Rold * ( 5 - VLED )) / Vold

This is designed to work with sensor bars where one resistor serves both banks, provided you measure the voltage across the two banks of LEDs together, or where both banks are in parallel and each bank has a resistor, provided you measure the voltage across each resistor separately and each bank of LEDs separately.

If this is confusing, then follow just the buying things step, open the bar up, and take a good picture. I may be able to guide you through the rest.

(08-22-2013, 10:09 AM)ulao Wrote:
Quote:Well if Nintendo's bar works, then a homemade bar with the equivalent number of IR LED should work in the same setting right?
Not sure what makes you think that? A usb puts out 4.7-ush volts and is not steady, especially if you have more devices on it. The Nintendo puts out 7 something I think ( been a long time since I have looked it up). Most people think its 12 or 9 and that is way wrong.

Mine had 11 across the whole thing. I'm pretty sure the Wii regulates the voltage across the sensor bar by putting it in series with a resistor, so different sensor bars with different resistances get given different voltages.

**ulao** · (This post was last modified: 08-22-2013, 10:23 AM by ulao.)

I'm not trying to dig on AnyOldName3 in any way at all, I'll speak for him, he is good at what he does.

that said "the output voltage of USB 2.0 is 5V," is not right. This just goes to prove my point, you can not trust that at all. The normal voltage form a usb port is 4.7 but may change from computer to computer and most certainly if you have devices on the chain.

Higher quality IF-LEDs the more fluctuation they can take. Cheep ones will not.

**AnyOldName3** · 08-22-2013, 10:33 AM #7

Given that my voltage drop is also out from the ideal by more than .3 V, I'm pretty sure that the difference isn't big enough to have a major effect. When googling I found the figure 'About 5V' cropping up most frequently, so went with it. The LEDs in my bar are probably some of the cheapest available, and have survived fine with normal USB fluctuations, as well as when I thought I may have to do without resistors, so tried just shorting them out to give the full 4.7 across the LEDs. From my experience, it's unlikely they'll be finicky enough to degrade from a slight miscalculation of voltage or small fluctuations.

Worst case scenario, this costs £5 (or equivalent) and is a bit too dim. If that's the case, the resistance can be further lowered.

**ulao** · 08-22-2013, 11:27 AM #8

Sounds good how long has it been going for, and when are you going to OC that damn processor.

moccor · 08-22-2013, 12:46 PM #9

Oh wow, yeah I did not take into consideration this many things and I too thought that USB was simply just 5v. But what I meant about building my own VS buying one, is because I bought a Dremel from Amazon recently and those idiots boxed up a used one and sent it to me. These days nobody can do anything right so we have to do it ourselves. Tbh I thought it would just involve some resistors and the IR LED's haha. It's been a while since I learned about this stuff, but I have learned about it and I do know how to solder, that's why a diagram/schematic would be fine to follow. But I mine as well just buy one then like yous said and use it like that or mod it for USB. I've been wanting to get/make one of these for a while but I kept forgetting. Already have some USB cables I could use though. And thanks a lot for the info. Can't really use all of it yet though, gotta order me the bar and also wait for shipping

**AnyOldName3** · 08-23-2013, 09:15 AM **#10**

(08-22-2013, 11:27 AM)ulao Wrote: Sounds good how long has it been going for, and when are you going to OC that damn processor.

I set it up late Feb 2012, and it's been on whenever my PC's been on during that time, so at least the equivalent of 8 months continuous use.

I'm going to OC before I sell my brother my GPU and get a new one, which will be before Sept. 23rd as I've bought him a Steam key for Skyrim, and he's not going to do too well with an HD 6450.