Does anyone have a good solid power supply they would recommend for working with prototyping LED projects? I am working on a matrix system, but the only solid performance from power that I get seems to come from USB ports. I have tried 5v DC wall warts and other odd jobs from spark fun. Anytime I use anything other than the USB port on my laptop, I get Jitter in the lights (WS2812B’s), or just general unstable performance.
It looks like I am going to have to get a solid bench power supply, but I wanted to see what the community recommends.
How many LED’s in your matrix? 64 or 640 makes a LOT of difference. I use portable USB power banks for small projects. of up to about 64 LED’s (with power managed code).
Also, what are you using to drive the LEDs? If it is something arm based, with a 3.3v output, something to be aware of is that any of those 5v wall warts put out 5.3v which can screw up the world when you are driving the data line with 3.3v, in which case you should be extra sure to be using level shifters on the data line.
I agree with @marmil he has a good suggestion there.
I have purchased a few of those for different projects. They are cheap but they work very well.
You can get smaller ones for even cheaper but as a bench unit, this is a good choice. Just one of them can easily power-up to 500 (or more…) WS2812 at a surprising level of brightness without problems !!
The only negative is the insufficiently protected AC input terminals. Keep children away !!!
@Daniel_Garcia
I am using the Teensy 3.1. It is isolated aside from the data pin. Powering the matrix is most successful when I use an Arduino on another port and only utilize the VCC and GND.
@JP_Roy
Thanks JP. I’ll be looking at one of those that Marc linked. Hopefully I can get one quickly and give it a shot.
You say the Teensy “is isolated aside from the data pin”… which makes me think if you are powering the LEDs with a wall wart, and your Teensy is powered from your USB, and there isn’t a common ground wire between them that could also make the LEDs erratic. If you haven’t already done it, make sure you connect ground between the Teensy and LEDs.
Those power supplies usually have a voltage trim pot. You can turn it down, so the power supply outputs about 4.7V, which gives less heating in the LEDs and better signals than 5.3C. But still, you should use a level shifter. http://www.pjrc.com/store/octo28_adaptor.html
I use a power supply from a desktop computer. You can buy brand new ones for around $10-15, but I always manage to find them at thrift stores for $5 or less, or salvage them from discarded computers. They give you 12v and 5v. Obviously not portable, but cheap and effective for prototyping or powering stationary projects.
@Daniel_Garcia
Are you referring to the PWM signal? Is the level shifter to get the data signal up to 5v from the teensy?
@marmil
You are correct Marc. I’ll verify my wiring, but I am pretty positive all my GNDs are connected to create a common.
@PaulStoffregen
Thanks! Is my question to Daniel correct. I am still learning about electronic components.
@allanGEE
Hi Allan, I have tried using a power supply from a desktop, but can’t seem to get a good response. However, it’s the only one I have and it could be bad. I’ll try another one and test the voltage.
Be careful if trying to use a PC power supply. Many of the modern ones do not work properly without a load on the 12V line. Even supposedly good quality name brand ones can have trouble. Some can output 7V or more on the 5V line, or generate short duration spikes in excess of 9V, when 12V line is unloaded.
You need to put a load on the 5V line. A 10 ohm, 10 watt resistor between the +5V and ground (one of the black wires) should be sufficient. I have my resistor on a heat sink with a computer fan blowing over it. There are a ton of tutorials on the subject, and pin diagrams for just about every connector you might run into. I’ve had no problem using them as a 12-volt source for a lipo battery charger, or as power supplies for a number of projects. Also, if you go to thrift stores frequently, always check that bin full of wall warts. I’ve come across a few 5-7 volt ones with 2A or more – and rarely pay more than a couple of bucks for them.