why will my 3v led work with appropriate resistor via usb or small 6v battery pack but not my phone via mini usb

Thread Starter

digixz

Joined Apr 3, 2020
20
why will my 3v led work with appropriate resistor via usb on my comp or via small 6v battery pack but not my phone via mini usb please i am complete knob
and need your assistance many thanks
 

djsfantasi

Joined Apr 11, 2010
7,825
thank you but there are hundreds of videos where the leds are on a board working from the mini usb power leads samsung say output voltage is 5V / 0.8A.
What type of phone do you have and what type of USB port does it have? Is it USB C?

There is also at least one page on the web, that states that normally, you CANNOT do this.

It all depends on the details which you haven’t supplied yet.
 

SamR

Joined Mar 19, 2019
3,483
P = IE You might have 5V from your phone USB, but not the Amps needed. And that looks like a fairly high powered LED.
 

Thread Starter

digixz

Joined Apr 3, 2020
20
thank you sam the specs for my led as follows
Size (mm) : 3mm
Lens Colour : Water Clear
Peak Wave Length (nm) : 395~400
Forward Voltage (V) : 3.2 ~ 3.4
Reverse Current (uA) : <=30
Luminous Intensity Typ Iv (mcd) : Average in 2000
Life Rating : 100,000 Hours
Viewing Angle : 20 ~ 25 Degree
Absolute Maximum Ratings (Ta=25°C)
Max Power Dissipation : 80mw
Max Continuous Forward Current : 30mA
Max Peak Forward Current : 75mA
Reverse Voltage : 5~6V
Lead Soldering Temperature : 240°C (<5Sec)
Operating Temperature Range : -25°C ~ +85°C
Preservative Temperature Range : -30°C ~ +100°C
 

Thread Starter

digixz

Joined Apr 3, 2020
20
no sam that is not mine that is one from youtube which can be seen working mine is a single 3v led just not able to work it out
works on battery pack works on usb from computer just not working on mini usb from phone
 

djsfantasi

Joined Apr 11, 2010
7,825
you can see one being made here
So what’s the point? I said that it would work for SOME phones, but not all. First, the phone must use USB C. Other USB standards do not support slave power out. And not all phones do. iPhones don’t work for example.

Did you read the link I attached? It clearly explains this. I don’t think you did, because you still haven’t answered what phone you have and which USB standard it supports.
 

Thread Starter

digixz

Joined Apr 3, 2020
20
sam as i stated at the top of my post i am a knob i have no idea i spoke to somebody on freelancer an he suggested this chip
MCP1700T-1202E/TT
but as i said i know narda and was hoping somebody with the appropriate knowledge might share it i have seen a number of videos where the phone has the capability to run as you said up to 12 leds :eek:) i only want to run 1 tiny little wee led
 

djsfantasi

Joined Apr 11, 2010
7,825
yes i read the post i have tried it on usb c thank you for your input
What did you use to try it on USB C ?

Let’s simplify this. What is the make and model of your phone where it doesn’t work?

And did you measure the voltage on the wires from the phone’s USB ?
 

Thread Starter

digixz

Joined Apr 3, 2020
20
and regards the iphone enter this do iphones allow power out from usb ?
Yes, you can. It converts the AC power to the standard USB power ?
 

djsfantasi

Joined Apr 11, 2010
7,825
and regards the iphone enter this do iphones allow power out from usb ?
Yes, you can. It converts the AC power to the standard USB power ?
I did. That article talks about an “iPhone Adapter” powering other devices. I still cannot find a reference that an iPhone can power an external device, i.e., your LED.

The tip is the reference to “AC Power”. A phone doesn’t have AC Power.
 
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