To avoid these ads, REGISTER NOW!

Help conducting a mini home lab for small LED

Poolshark314

Well-known member
Joined
Jul 5, 2021
Messages
658
Location
MD
Ordered some tiny LED chips to play with very similar to these:


I was planning on running just a single one of these at a time on a 12v car battery through some wire I have laying around (16ga). Each bulb is rated for 300mA which means I could safely go down to a much smaller wire like 22ga since that is still rated for well over 1 amp.

The item has a note:
【Note】-The LED lamp board must be powered by constant current LED driving power supply, and the output parameters of the power supply are consistent with those of the lamp board;The LED lamp plate must be installed on the aluminum radiator,otherwise the lamp plate is easy to burn out at high temperature

Does this mean I need to use a resistor or buck converter in between the bulb and the power source in order for this to work correctly?
Has anyone ever seen a heatsink that would fit a bulb like this?
 
To avoid these ads, REGISTER NOW!

markhm

Well-known member
Joined
Mar 4, 2017
Messages
264
Location
NY
Constant Current means you have to get a 300ma driver for each LED. That driver must be rated for 9v.
 

dcg9381

Well-known member
Joined
Jun 20, 2018
Messages
11,883
Location
Austin, TX
Constant Current means you have to get a 300ma driver for each LED. That driver must be rated for 9v.
Doesn't it mean that you need a driver capable of delivering 9v-11v (voltage) and at least 300ma? IE - if you're going to drive more than one, you just need a source / battery capable of that amperage.

You'll voltage divider resistor (properly rated watts) to knock 12V down to the 9v-11v range. 12V batteries operate over 12V.

They want you to mount this on a "radiating plate" - I don't know of one designed to fit this particular board, but if you look at the assembly of typical "UFO lighting" - you'll find that they're basically massive heat sinks with much larger LED arrays. To me, I'd mount this to something aluminum with thermal paste (like you use for PC CPUs).

A quick search for LED heat sink came up with stuff like this (confirm sizing): https://www.harfington.com/products/p-1099054?_pos=36&_sid=a93690d24&_ss=r
 

dcg9381

Well-known member
Joined
Jun 20, 2018
Messages
11,883
Location
Austin, TX
No, it meaans exactly what it says "constant current" meaning that the current is regulated.

Interesting, so these are not self regulating and you have to control both amps and voltage... I'd think it would be easier to put a limiting device in front of them if powering from one source.
 
To avoid these ads, REGISTER NOW!

ycgoat

Well-known member
Joined
Mar 28, 2020
Messages
971
Location
S.E. Va
IMHO, a current limiting resistor and 12v battery is a constant current driver
 

Innovate1

Well-known member
Joined
Jul 28, 2014
Messages
4,292
Location
Illinois near St. Louis, Missouri
IMHO, a current limiting resistor and 12v battery is a constant current driver
Nearly constant current and close enough for most applications if the voltage of the source is several times the voltage of the load (which isn't true for this case). Given the voltage rating the LED elements are in series. So the voltage is about 10 V. So the resistor has to drop 2V at 300mA. That is about 6.6 ohms. But if the voltage goes up to 14V (as in a car) the current would be 600 mA. ****. The bulb is gone. You need a switching regulator. You also need to attach these to a heat sink with thermal grease to keep them from overheating.
 

walta

Well-known member
Joined
Jan 13, 2017
Messages
2,313
Location
Dutzow Missouri
Yes, you could use a fixed resister to limit the current flow thru the LEDs in the link but it will be far from ideal. You would need to size the resister for the highest voltage to limit the current to 300mA. When you are charging the battery, its voltage would be close to 15 volts and the batteries voltage may well drop close to 10 volts before you recharge the battery. Your battery is far from a constant voltage output so with a resister the current thru the LEDs will vary with the battery voltage. When the current varies the quantity and quality of the LEDs output will vary.

An active device in the circuit will make for a better light output.




Walt
 
OP
P

Poolshark314

Well-known member
Joined
Jul 5, 2021
Messages
658
Location
MD
Thanks for all the replies so far! I'm going to try a step down converter to 9v and see how it goes
 

Uofime

Well-known member
Joined
Jan 11, 2021
Messages
174
Location
Charleston SC
RDTech make really nice, inexpensive buck and boost converters with CC and CV modes. They sell housing options and supply options too. I wanted to use a spare laptop power supply and keep it as small as possible so I put together my own solution. They work great. I got mine off their store on aliexpress but a bunch of people sell them(usually with more mark up)
FD07F40E-11D6-4243-BE2D-611DF279F546.jpeg907398EB-F107-4971-A144-8CF5110A8D6C.jpeg
 
To avoid these ads, REGISTER NOW!
Top Bottom