Help wanted: building LEDs into a headset

[M11C]

first post here. I'm doing a home project, and in need of advise.

instead of me asking wild spread questions, I'll just start be describing what i had in mind.

I'm currently re-painting a Steelseries Neckband headset as it only comes in white, and wanted to add some neat things while i have the headset disassembled.
the headset have a built in microphone, but I'll rarely use it, since i have a usb headset for my computer. so i wanted to build in a jack connection for the mic, so i don't have two cables, or a dual cable, which would also make it easier to maintain eg. replace the cable.

but that's not the tricky part, the reason i wanted to create a separate port for the mic, is that i mostly use the headset with my iphone, winch support a 4 pole cable, and then use what is normally the mic. poles to run power to LED diodes i want to build into the headset, pulsing in tact with the music.

from what i understand the analogue audio signal is AC and at about 0.5 volt.
I'm not sure about the mic.

the materials i have PT.:
diodes, model no. number 1N5819, to make a rectifier. which leads me to the question whether i should full or half wave, since half wave might give a more clear blinking with less flickering, but at a power loss...
capacitor 100uf, 16 volt, for the step up
various blue LEDs, but i don't know the specifications of these. how can i find out?
i have 5 very small LEDs with resistors already attached, they they are under shrink tubing, so a can't read them. but I'll probably use the 5mm LEDs, if possible, since i have a lot, and they give more light.
12 Ohms 5% resistors
2 circuit board mini jack connectors, though i don't know whether they are 3 or 4 pole.

the headset has an impedance of 40 Ohm
last, how would i disperse the light in a acrylic disk, to give a smooth and not blinding light?

please excuse how poorly written this is, English is not my first language, and I'm new at this. i hope somebody can assist me in this project.
in the mean time i'll do some research, which i should already have before posting, but i learn 10 times faster by experience, than reading, so this will be a build and project status log.
I'm looking forward to the end result, and i hope to be able to share it with you guys.
---
Update
so i finished painting, and finally got around to assembly the haedset, after i got a new soldering iron. next i need to make the microphone port, and the LED's.
but so far i think it looks like porn, compared to the original:

and it looks nice with my 900D as backdrop.
i'm considering making a gold stribe on the plastic next to the pads.
---
*edit*
collected information:
blue LEDs run at about 3.5V, 25-50mA
AUX supply ~1V pk-pk, and 30 mW per channel, 60 mW total.
microphone line supply 2V (needs 200 to 5000 ohms impedance. (1600+ "operational"))

TRRS pins:
TIP = left headphone out
RING = right headphone out
RING = ground
SLEEVE = mic in+ plug-in power

 

[DerStrom8]

Hi M11C, welcome to ETO!

First thing I'll mention, which was mentioned in the chat earlier, was that the voltage on the audio jack is generally around 1 volt pk-pk. Blue LEDs tend to take around 3.5v and 25-50mA. You're not going to get anywhere near that directly from the jack. I would suggest an op-amp or transistor-based audio amplifier to boost the signal, but you'll need an external power source. Either that or a boost converter, but I'm not very familiar with them.

Hopefully some of the others will be able to offer more information

Good luck,
Matt

 

[M11C]

Hi Matt, thank you for your answer. i didn't see the reply on the chat, so thank you for providing that.
i knew i'd had to step up the voltage, and from i know i'd be easier on the AC side of the signal, but i had hoped i vouldn't need an external power source.
do you know how much power i can draw over the microphone line on a 4 pole cable, from the iphone?
i'll look into the components you mentioned.
- M11c

 

[DerStrom8]

Hi M11C,

Headphone and microphone cables really are not intended to handle any significant amount of power. They generally only see about a volt peak and maybe a few microamps (though I could be wrong here. Hopefully audioguru will be able to offer some insight in this thread).

A couple of button cells may be enough to power any external circuitry, including the LED, provided you make sure it doesn't draw much current. Again, I'm out of my area of expertise here--never did much with audio--so hopefully someone else can tag in

Regards,
Matt

 

[M11C]

i've been doing some searhing, and found that the AUX supply 30 mW per channel, 60 mW total.
but the microphone line supply 2V, when i mic is connected, so i need to simulate that as being 200 to 5000 ohms impedance. (1600+ "operational")

also found this little device, wich might come in handy:
https://hackaday.com/2007/10/10/joule-thief-led-driver/

with a rectifier i simply "flip" one side of the wave, is there a way to "push" to wave to one polarity, so you still have the wave sine?

if i opted to have to LED light continously, would i be able to acchieve this using just a capasitor?

 

[audioguru]

A Joule Thief circuit dimly and continuously lights an LED from a single battery cell that is almost dead. It cannot be blinked with music.

An LM386 audio power amplifier IC can amplify the audio and drive up to 15 pairs of LEDs at 20mA each from a 9VDC power supply. Here is a very simple circuit that blinks the LEDs to the loudest sounds of music and speech:

 

[M11C]

hi, thank you for your answer.
well, what i wanted to know is, if it is possible to run just 2 LEDs through the power that is provied by the speaker and microphone line of an iphone?

because the microphone lie supply 2v to microphones over 1600 ohm. blinking or not doesn't really matter at this point, as long as i can get a prototype working.

with a rectifier i simply "flip" one side of the wave, is there a way to "push" to wave to one polarity, so you still have the wave sine?

Best regards, Michael

 

[DerStrom8]

well, what i wanted to know is, if it is possible to run just 2 LEDs through the power that is provied by the speaker and microphone line of an iphone?

Simple answer: No. Not without an external power supply.

 

[M11C]

Simple answer: No. Not without an external power supply.

i guess i'll have to try me way forward. would have been ealier with an oscilloscope though -_-

if i use an external power supply, what voltage would i need for two blue LEDs?
and if so i want to build it into the headset, can i get small coin size recharable batteries, and how would i build the recharging circut?

 

[DerStrom8]

As I told you before, most blue LEDs require at least 3.5 volts and 15-50mA (you can usually just assume 25mA). But don't forget that you'd need to power external circuitry as well as the LEDs (that is, if you want to modulate them based on the audio), so that would require more voltage and current.

I am not aware of any rechargeable coin cells. You'll probably want a battery pack, but those tend to be relatively large (think cordless phone batteries).

 

[audioguru]

Coin batteries are made to power a very low current clock, not high current LEDs. They are not rechargeable. A CR2032 pretty big coin cell is rated at only 0.19mA. One LED uses 20mA which is 105 times more.

Hobby stores sell small inexpensive rechargeable 7.2V Li-Po batteries that are made to power electric radio controlled model airplanes with a lot of power. The also sell very good inexpensive chargers for them.

 

[audioguru]

Coin batteries are made to power a very low current clock, not high current LEDs. They are not rechargeable. A CR2032 pretty big coin cell is rated at only 0.19mA. One LED uses 20mA which is 105 times more.

Hobby stores sell small inexpensive rechargeable 7.2V Li-Po batteries that are made to power electric radio controlled model airplanes with a lot of power. The also sell very good inexpensive chargers for them.
The circuit I posted needs a few changes to light 3.5V blue LEDs from a 7.2V battery that drops to 6.4V per charge.

 

[M11C]

okay, so i've been looking around for batteries, and have found one i think has the format i can fit into the headset. so now the question is if it is enough.
it is this one:
**broken link removed**
will one be sufficient?

btw. foud this, wich would argue that you can i fact run LEDs from a coin battery:
https://www.instructables.com/id/LED-Throwies/

 

[audioguru]

There are many fake Lithium batteries sold on ebay. The one you show says the color of the batteries might be random so they do not know or do not care where they come from. So some might be fakes.
Those cells are pretty big and heavy. You need two cells in series.

Some Instructables are written by little kids who are only 10 years old and know NOTHING about electronics.

The datasheet for an Energizer CR2032 lithium coin battery shows that it is designed for a 0.19mA load. An LED needs a current that is 20mA which is 105 times higher.
The datasheet shows a pulse with a current of 30mA. The new battery starts with a voltage of 3.25V and with the load it immediately drops to 2.95V then it drops to 2.8V in only 2 seconds. Its voltage is dropping fast.

Here is a reliable rechargeable battery that is sold in hobby stores. It is small and lightweight but is powerful. It has a connector that you can push two wires in for connections. It is 8.4V when fully charged and is 6.4V when it should be recharged.