22-11-2018, 15:25
|
#1
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
How much amps do I need?
Hi,
I'm planning on playing around with some LED lights (well a variation on neopixels..).. and I'm trying to workout the power supply that they would need.
Wattage: 0.3W/pixel
Working voltage: DC 5V
50pcs pixel per string
so.. from my googling....
amp = watt / volt
which means : .3/5 = 0.06
so each pixel draws 0.06 amps, right?
so 50*0.06 = 3amps..
and if I wanted to run 100 lights, I'd need 6 amps?
So a power supply that can give 5V and 6+amps should be good right?
Just want to make sure that I'm looking for the right thing...
Thanks!
|
|
|
22-11-2018, 17:23
|
#2
|
Perfect Soldier
Join Date: Mar 2009
Location: Worthing West Sussex
Age: 66
Services: VM 500M SH3 thingy
in modem mode
XL TV V6 Sony Bravia smart TV and M phone
Posts: 10,994
|
Re: How much amps do I need?
Yes. You've got it right. Volts x amps = watts for DC circuits.
__________________
History is much like an endless waltz: The three beats of war, peace and revolution continue on forever.
However history will change with my coronation - Mariemaia Khushrenada
|
|
|
22-11-2018, 17:47
|
#3
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
Quote:
Originally Posted by heero_yuy
Yes. You've got it right. Volts x amps = watts for DC circuits.
|
awesome - thanks.
I would rep you, but apparently I haven't spread it around enough...
|
|
|
23-11-2018, 09:55
|
#4
|
cf.mega poster
Join Date: Jun 2003
Location: Kairdiff-by-the-sea
Age: 68
Services: TVXL BBXL Superhub 2ac (wired) 1Tb Tivo
Posts: 9,811
|
Re: How much amps do I need?
There is usually a bit of switch-on surge current in most electronic circuits, so I'd rate the PSU a bit higher, at least 10%. Plus running a PSU at it's maximum rated current can often reduce its life.
|
|
|
23-11-2018, 10:13
|
#5
|
Perfect Soldier
Join Date: Mar 2009
Location: Worthing West Sussex
Age: 66
Services: VM 500M SH3 thingy
in modem mode
XL TV V6 Sony Bravia smart TV and M phone
Posts: 10,994
|
Re: How much amps do I need?
Always a good idea to have some in reserve. When I fitted LED lighting strips in the kitchen (above and below the cupboards) I used a PSU of double the rating I needed. Very little cost penalty and handy as later I added more LEDs to light the gallery rails and shelves without any worry that the PSU would be overloaded.
__________________
History is much like an endless waltz: The three beats of war, peace and revolution continue on forever.
However history will change with my coronation - Mariemaia Khushrenada
|
|
|
23-11-2018, 12:23
|
#6
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
Thanks for the advice.
I'm looking at an 8A power supply - which should be more than enough, I was finding that anything higher than that I was needing to get from China.
This is really for some christmas tree lights, so I don't imagine I'll be adding lots more other than the original 100...
My plans are stuck at the moment, as I need one of these : https://thepihut.com/products/adafru...o-5v-74ahct125 - but they're out of stock everywhere
---------- Post added at 12:23 ---------- Previous post was at 10:49 ----------
Been having a dig around, so I've found this : https://thepihut.com/products/adafru...-level-shifter but I think that only shifts from 5v to 3.3v - so don't think that would do.
but... I was rummaging through my component box, and I found one of these : https://thepihut.com/products/adafru...verter-txb0108
That should let me shift from 3.3v to 5v right?
|
|
|
23-11-2018, 14:28
|
#7
|
cf.mega poster
Join Date: Jun 2003
Location: Kairdiff-by-the-sea
Age: 68
Services: TVXL BBXL Superhub 2ac (wired) 1Tb Tivo
Posts: 9,811
|
Re: How much amps do I need?
The Level shifter is for logic circuits only, It cannot drive LED's.
---------- Post added at 14:28 ---------- Previous post was at 14:26 ----------
https://www.tlc-direct.co.uk/Main_In...mer/index.html
|
|
|
23-11-2018, 14:34
|
#8
|
Perfect Soldier
Join Date: Mar 2009
Location: Worthing West Sussex
Age: 66
Services: VM 500M SH3 thingy
in modem mode
XL TV V6 Sony Bravia smart TV and M phone
Posts: 10,994
|
Re: How much amps do I need?
That level shifts control signals. So if the driving device, such as a raspberry pie is on 3.3v and the neo pixel is on 5v then the signals will interface correctly.
Often you will find that the slave device even on 5V will happilly accept 3.3v control signals directly.
Can you say what the LED neo-pixel part is and what you intend to use to drive the interface line(s). Then I could check the levels for you.
Here's a useful resource: https://learn.adafruit.com/adafruit-...c-of-neopixels
__________________
History is much like an endless waltz: The three beats of war, peace and revolution continue on forever.
However history will change with my coronation - Mariemaia Khushrenada
Last edited by heero_yuy; 23-11-2018 at 14:37.
Reason: Resource link
|
|
|
23-11-2018, 14:51
|
#9
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
Quote:
Originally Posted by heero_yuy
That level shifts control signals. So if the driving device, such as a raspberry pie is on 3.3v and the neo pixel is on 5v then the signals will interface correctly.
Often you will find that the slave device even on 5V will happilly accept 3.3v control signals directly.
Can you say what the LED neo-pixel part is and what you intend to use to drive the interface line(s). Then I could check the levels for you.
Here's a useful resource: https://learn.adafruit.com/adafruit-...c-of-neopixels
|
Essentially looking to do as in the picture here.
using something like this : https://www.amazon.co.uk/ALITOVE-Dif.../dp/B01M7TN8A2 in terms of lights, and this : https://www.amazon.co.uk/Switching-A.../dp/B0174JDFWE as a power supply
|
|
|
23-11-2018, 14:53
|
#10
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
Realise my posts are probably confusing - as I'm asking 2 different questions in the same thread - one was about a power supply for the LEDs, and the other was about a logic level converter for controlling the LEDs.
|
|
|
23-11-2018, 15:07
|
#11
|
Perfect Soldier
Join Date: Mar 2009
Location: Worthing West Sussex
Age: 66
Services: VM 500M SH3 thingy
in modem mode
XL TV V6 Sony Bravia smart TV and M phone
Posts: 10,994
|
Re: How much amps do I need?
I did cotton on as the LEDs are controllable. In addition to the reference I posted above here's another that might be of use:
https://www.edn.com/design/led/44387...trips---Part-1
Sounds like a fun project. I like the idea of being able to control the colour of each LED individually. Good luck.
If you have any technical questions please feel free to ask as I'm an electronics and software (primerrily embedded C) engineer by profession.
__________________
History is much like an endless waltz: The three beats of war, peace and revolution continue on forever.
However history will change with my coronation - Mariemaia Khushrenada
|
|
|
23-11-2018, 15:23
|
#12
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
Quote:
Originally Posted by heero_yuy
I did cotton on as the LEDs are controllable. In addition to the reference I posted above here's another that might be of use:
https://www.edn.com/design/led/44387...trips---Part-1
Sounds like a fun project. I like the idea of being able to control the colour of each LED individually. Good luck.
If you have any technical questions please feel free to ask as I'm an electronics and software (primerrily embedded C) engineer by profession.
|
I'll let you know how it goes - hopefully with a video
I'm a software engineer too, so hopefully codewise I'll be ok, but I'm sure I'll be back with more electronics questions
|
|
|
07-12-2018, 12:23
|
#13
|
Inactive
Join Date: Jun 2003
Location: London way
Age: 48
Services: Sarcasm
Posts: 8,376
|
Re: How much amps do I need?
I've got my lights all working now, and written routines that run for several minutes. I'll post a video of them working in all their glory later
|
|
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT +1. The time now is 07:28.
|