3.5 mm trs jack power carrying points

[venky srinivas]

gyuz i wanted to know which point of the 3.5 mm trs jack carry the negative and positive current that is the TIP,RING,SLEEVE out of these which carries current....

 

[nukemaster]

Before wiring anything, you need to see if the OTG cable even gives you power. If it does not, all this work is for nothing.

Even a cheap meter will help you better understand what is going on.

USB cables have power on the outer edges on the normal PC style plug that most of these OTG cables become. The issue here is if the device has to negotiate before allowing power or not. I do not use OTG so have never looked into it.

To get your self started maybe you should take power from a normal usb port(very carefully, do not use the data pins, just keep then from touching anything and tape them off separately).

Take the Black wire and connect it to the LED's cathode end(on a normal led it has a shorter pin and is the longer side inside the led, but you may not be able to see that on this setup). Connect the resistor(for 5 volts lets use 120-200 ohms or so to limit yourself to 15-20ma current flow) to the other lead on the LED(anode) and the other end of the resistor to the red wire. With a meter you can be 100% sure what you are connecting by pre checking the power.

If all is good this will allow a computer usb port to light your led.

Please note starting with a large resistor(I have a 5k 1 turn variable that allows better control to find just how much light I would want. It was picked up for something else, but works for this as well) and working down is a good way to fine tune the brightness.

I can not offer you a simple yes or no answer on how to connect to your device because I do not own the device and they do not make the specs available to the general public. The mic wire may have 5 volts or only 1.5. I have no way to tell and again current limits are another issue.

This is a writeup that has some info on how the OTG setup works. You will quickly see that without being designed for it, chances are it will not work for your application.
http://www.ti.com/lit/wp/sszy001/sszy001.pdf

 

[venky srinivas]

hii nuke after a long time i tried the experiment u told nd the led glowed through laptop nd will it glow through the micro usb i tried it did not glow what to do now ....

 

[nukemaster]

So it glows from USB and not from the phone?

That just means the phone does not provide power from its usb port(even on the go ports may not provide anything without being told to.).

 

[venky srinivas]

well nuke how to know that my phone does haave a built in diode i watch my mobiles teardown but there was not mentioned any diode i had the faulty usb cable so may it be the issue

 

[nukemaster]

Honestly my the way that Li-ion chargers work, I do not think you will ever get power out of the usb port unless it was designed for it(on the go or similar has been designed from the ground up to not only give you power, but make sure it is 5 volts.).

I have looked quite deep into getting power out of such devices and it simply does not work. Looking at MANY different usb chargers they are all built to prevent any power from moving in the reverse direction. This protects the IC's(these ic's can do many things and are not that easy to identify from a tear down video) dealing with the charging as well as the device providing the power.

 

[nukemaster]

This is still not to say you can not run the led flash off of a battery pack. It is safer and should be easy to do.

 

[venky srinivas]

Honestly my the way that Li-ion chargers work, I do not think you will ever get power out of the usb port unless it was designed for it(on the go or similar has been designed from the ground up to not only give you power, but make sure it is 5 volts.).

I have looked quite deep into getting power out of such devices and it simply does not work. Looking at MANY different usb chargers they are all built to prevent any power from moving in the reverse direction. This protects the IC's(these ic's can do many things and are not that easy to identify from a tear down video) dealing with the charging as well as the device providing the power.

 

[venky srinivas]

hello then should i stop my expermet i have searched on the net my mobile does not have the diode ....

 

[nukemaster]

Again, due to the charging system used on modern electronics they will all have some way to prevent power from flowing backwards.

Even on to go phones / devices will need to negotiate before switching on the ability to send out power.

I highly recommend you build a battery back OR use an battery powered usb charger. This will always give you 5 volts making it easy to use with almost any LED.

I am sorry this did not work out, but power from the headphone jack was going to be difficult and do get any useful voltage you would need to make it play a sine wave, rectify that sine wave and then boost that voltage to something usable. This all requires parts. While not overly costly, it would be not recommended for a first project.

 

[venky srinivas]

what is a sine wave is it mp3 if then i can play it how much amount of current will be given out nd also where can i get this sine wave sounds

how can i contact u whatsapp? i m running out of time for this project pls help

 

[venky srinivas]

what is a sine wave is it mp3 if then i can play it how much amount of current will be given out nd also where can i get this sine wave sounds

how can i contact u whatsapp? i m running out of time for this project pls help

 

[nukemaster]

A sine wave a steady ramp upto a positive and down to a negative(in this case). It is a AC wave that has more voltage and a nice high peak. This is why it can work under the right circumstances. and LED will only make use of the rising part of it.

You can download a tone generated sine wave off the internet or even get on on youtube.

To get the most power of it t, you would need a rectifier. this will cost you voltage. In order to get the higher voltage you want, you need some kind of boost converter or charge pump.

This is way outside the scope of a first time builder.

If you playback a sine wave on your phone and measure the output from the headphone jack, you will see how many volts RMS the device can produce. If this number is too far under the forward voltage of an LED, it will not even light(resistor or no resistor).

I do not quite see what you are trying to do aside of extract power from the phone to run a flash. This is a job that can much more easily be done with 4 aaa batteries(could use less, but 5 gives you a nice 6 volts to work with.) and a single resistor.