Press "Enter" to skip to content

Posts published in “Science & Technology”

Good 5, 9, 12V PSUs that aren’t brick sized

Having now spent/wasted about a day looking for a problem that turned out to be a bad PSU bought too cheaply from a "Chinese vendor", I'll like to ask where people get PSUs from that aren't big bricks to provide more than 1A? 40-60W would be typical range for final projects. So is there a good place to look for reliable PSUs that actually does what the label claim it does?

submitted by /u/egoalter
[link] [comments]

Are SP901E as bad as mine is turning out?

I have a SP901E (https://smile.amazon.com/BTF-LIGHTING-Amplifier-Repeater-Addressable-Programmable/dp/B07RDKRW5T) which took me too long to actually hook up as the project I intended to use it for kept getting pushed out. Now that I finally get around to it, I doubt this is useful AT ALL.

I'm seeing very little voltage regulation. I have a 4A 5V supply hooked up, and two WS2812 strips hooked to it, with 600 LEDs total - the final design will have these LEDs spread in smaller segments and all 8 will end up being hooked up to this (well, that was the plan anyway). What I wanted to do was use a single PSU to power the ESP82666 and the strips, using this unit to handle the current rush when the LEDs go bright, flash or what-ever.

But what I'm seeing is that the voltage on the input drops - severely. In the current setup with 600 LEDs VCC dropped to 4.75v - the total AMPs is less than 1.5A for 600 LEDs - the patterns and intensity I am looking to use keeps the total current below 1A and still the VCC measured is 4.75v. This causes the poor regulator on my ESP8266 to fail and hence no show etc. Even with no signal input (all turned off) I see a voltage drop of 0.1v, and this voltage drop gets worse the more load the unit pulls.

I'm using the signal in to provide power to the circuit. It's not a direct flow - all other VCCs are connected together, but "something" is between the VCC of the signal-in and the main signal. I see power out when there's power to the main VCC, which I take for a regulated output but I'm not seeing that either.

So either I'm doing something crazy here or I need to just trash this cheap unit and find something better to power about 600 WS2812 LEDs in total.

"ledbe.com" has a good description of the typical hookups: https://www.ledbe.com/sp901e-spi-dream-color-magic-pixel-signal-amplifier but nothing that shows the schematics/diagram on how this is hooked up internally. I presumed the regulators and mosfets used were using the case as thermal cooling, although they advertise the unit only uses 1W of power, which cannot be true if it needs that much thermal cooling.

If you have this kind of unit, and don't recognize my problems please let me know. Perhaps I'm doing something crazy or I need to take a much better look at my PSU.

submitted by /u/egoalter
[link] [comments]