Alternate cutting point for LED strips - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: October 18, 2017, 04:56:12 pm
content: hello everyoneI'm doing a hobby project with some RGB LED strips. the LED strips is suppose to be fit inside an white acrylic casing. But unfortunately the casing can't accommodate the default length of the LED strips when cut at the inscribed cutting position on the strips. Since there is no room to fold the excess strip length I need to somehow remove the last LED on the strip which then makes it a perfect fit. Since the LEDs within two cutting segments are connected in series is it really possible to cut the excess off. I have attached my LED strip and my desired cutting position. Could anyone help me out??

author: katzohki
author_rank: Frequent Contributor
timestamp: October 18, 2017, 11:30:39 pm
content: It doesn't look like the circuit makes a return and everything seems to be parallel so it should be fine. If you have the datasheet on the strip it should be easy to confirm.

author: Brumby
author_rank: Unknown
timestamp: October 19, 2017, 12:11:48 am
content: Quote from: katzohki on October 18, 2017, 11:30:39 pmWRONG ADVICEDon't do it.There are 3 channels for RGB - and there are 3 LEDs in series (one in each package) for each channel. Each channel has a single resistor for current limiting - 150 ohm, 150 ohm and 330 ohm. I'll bet you the 330 ohm resistor is on the red channel.Cut where you have shown and you won't get ANYthing lighting up in that section. This iswhythey have the cut points clearly marked.You could trace out the appropriate paths and work out the proper resistor values to have just that section with one LED package light up - but I have an alternate suggestion for you....

author: Nusa
author_rank: Super Contributor
timestamp: October 19, 2017, 12:28:45 am
content: I agree, it's a series circuit. You can't cut out just one LED without compensating in some way.First solution I'd look at is eliminating the entire section and recentering the rest. Will the fixture be adequate in that configuration?

author: Brumby
author_rank: Unknown
timestamp: October 19, 2017, 01:00:33 am
content: Quote from: Brumby on October 19, 2017, 12:11:48 amThe backing tape is quite robust - how about just shortening the distance between the LEDs like this....You will get more LEDs in the space you have and, hopefully, get enough room to fit that last section in completely. Using a "former" like a match stick will allow for consistent bending - and hopefully look reasonable. You could play around with this idea - but it may have a downside if the adhesive backing isn't great.

author: Nusa
author_rank: Super Contributor
timestamp: October 19, 2017, 01:51:19 am
content: ^^^ Interesting idea that could work! You could snip off the bit AFTER the 3rd LED to reduce distance you need to recover.

author: Adhith
author_rank: Frequent Contributor
timestamp: October 22, 2017, 04:33:16 pm
content: Thank you everyone for your valuable explanations. I tried to stick a small length around 5mm to its adjacent portion to form a small hill like portion and it worked. I planning to move forward with this idea.