LED to the promised land? - Page 1
Forum section: electronics / general

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 27, 2020, 02:48:31 pm
content: I wonder if there is a product that has standard LEDs in a simple row of eight units all in one package?I've searched for "LED arrays" and the closest I get is bar-graph LEDs.It would be even better if the current limiting resistors were incorporated.

author: Ian.M
author_rank: Super Contributor
timestamp: August 27, 2020, 03:22:44 pm
content: I've seen 7x 5mm LED ones about 20 years ago - used in LED scrolling signs. I've absolutely no idea who made them - the sign company gave us a bag full for our contract repair work and we soon learnt you could simply pop the black plastic strip off the LEDs, desolder the one or two bad LEDs, push replacements into the strip being careful of pin alignment, refit it to the remaining LEDs and solder the new ones.

author: Gyro
author_rank: Super Contributor
timestamp: August 27, 2020, 07:22:57 pm
content: Quote from: PerranOak on August 27, 2020, 02:48:31 pmMaybe you mean an LED bar, eg.https://cpc.farnell.com/broadcom-limited/hdsp-4832/led-bar-array-multicolor/dp/SC12037?st=led%20barThey are sometimes also referred to as LED bargraph displays in searches.If you mean a single row of circular (rather than rectangular) LEDs in a package then you're probably out of luck. 3mm LEDs wouldn't fit standard 0.1" dip pin spacing - you would be better just putting down a row of LEDs (through hole or smd) on a PCB.

author: MasterT
author_rank: Frequent Contributor
timestamp: August 27, 2020, 09:40:43 pm
content: Check it out:https://www.adafruit.com/product/1426and circular:https://www.adafruit.com/product/1463https://www.adafruit.com/product/1586

author: thm_w
author_rank: Super Contributor
timestamp: August 27, 2020, 09:59:16 pm
content: May be possible to use a standard LED strip and cut it to length, the have resistors built in (mastert linked addressable, these are non-addressable):https://www.sparkfun.com/products/12021A lot of backlight LEDs come in this form as well, in smaller sizes, but I don't think distributors stock them, its just going to be a custom PCBhttps://www.aliexpress.com/item/32808784557.htmlIts not clear what you want, and what it will be used for... do they need to be individually controlled or not?

author: oPossum
author_rank: Super Contributor
timestamp: August 27, 2020, 11:23:12 pm
content: http://www.dialightsignalsandcomponents.com/Assets/Drawings/2D_Drawings_DrawingDetailedSpec/C16497.pdf

author: oPossum
author_rank: Super Contributor
timestamp: August 27, 2020, 11:24:39 pm
content: https://media.digikey.com/pdf/Data%20Sheets/Lumex%20PDFs/SSA-LXB102ID.pdf

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 28, 2020, 01:22:22 pm
content: Thank you for all those suggestions.It's to visualise the content of registers and other simple binary stuff. I get fed up with wiring-up 8 LEDs and 8 current limit resistors every time. I just wondered if there was a simple 8 LED array (preferably with built-in resistors) that I could plug in. It needs to be individually addressable LEDs and you need to be able to see the ones that are "off": if they're too close to each other you lose this.

author: MasterT
author_rank: Frequent Contributor
timestamp: August 28, 2020, 03:25:09 pm
content: Quote from: PerranOak on August 28, 2020, 01:22:22 pmUse colorful LED's, than "1" and "0" could be indicated with different colors, instead off "no lights" state.

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 28, 2020, 04:12:56 pm
content: Hmm. Interesting. Maybe green for on, red for off.

author: oPossum
author_rank: Super Contributor
timestamp: August 28, 2020, 04:48:55 pm
content: You can buy or build something that will plug into breadboards.http://www.ebay.com/itm/174049728427https://youtu.be/7NClJQR-1c4?t=1246

author: cdev
author_rank: Super Contributor
timestamp: August 28, 2020, 05:02:39 pm
content: A couple of years ago I got a Jameco "grab box" or junk bag or whatever they call it for $10. There were a lot of useful miscellaneous parts in it including a lot of those bars of replaceable LEDs. (also some bar graph style LEDs)Quote from: Ian.M on August 27, 2020, 03:22:44 pm

author: rdl
author_rank: Super Contributor
timestamp: August 29, 2020, 01:29:31 am
content: You can buy LEDs with built in resistors. They cost a lot more than the normal ones, like around 5-10x as much. I have some because they're convenient to use when breadboarding. Look for 12 volt or 5 volt vf when searching. I don't think they're available in styles other than the usual 3mm and 5mm round, but I haven't looked in years. Also, resistor arrays would be useful for what you want to do.

author: KL27x
author_rank: Super Contributor
timestamp: September 01, 2020, 06:10:36 pm
content: Well, how often are you going to be able to plug 8 LEDs in a row, in a breadboard, all using a common power or ground? Never. The pinout on your microcontroller or your logic chip or other output chip is not going to have 8 output pins in a row, esp not of the same port.For breadboarding, you might want to make individual pluggable LED units. The easy way is to use square 0.1" pin header and some 0.020" - 0.030" copper clad FR-4. Solder two pins onto a strip of copper clad, 0.4" apart. Pull that out of the header strip. Grind two lines in the copper to divide it into 3 pads. Stick it back into a blank piece of header plastic strip to hold the pins in place during assembly. Solder a resistor and a 3mm thru hole LED, so it points up. Solder the anode in a consistent direction.With 0.4" spacing you should be able to reach either power or ground rail on a standard breadboard. If you sand the 3mm LEDs a bit, you can stack them side by side in the breadboard, no problem.

author: Ian.M
author_rank: Super Contributor
timestamp: September 01, 2020, 06:38:23 pm
content: Actually, a DIP package 10 LED bargraph + a bussed SIL 11 pin resistor array is extremely convenient when breadboarding logic. You get 10 LEDs in a tiny bit of board with only one wire per LED + a ground (or Vcc) to the common of the resistor array. I typically either group the LEDs in nibbles, leaving the extras as blanks in between, or if there are also control signals stick them on the end LED(s). The inconvenience of not being able to stick it right on the chip its monitoring is more than made up for by the ordered display of the bits it provides. The only thing one could do better would be to make an eight LED module that buffers the LED inputs, and allows stacking end to end with consistent nibble spacing and white silkscreen space to write on. e.g. 'D7-D4 D3-D0'

author: KL27x
author_rank: Super Contributor
timestamp: September 01, 2020, 07:17:52 pm
content: Quote from: Ian.M on September 01, 2020, 06:38:23 pmI haven't used a breadboad in years, but you're preaching to the choir. I made a couple of 8 channel logic probes for this, probably over a decade ago. Fully buffered Mohms input, hi/lo/hi-Z dual color LED indicators. Each channel has DIP switch selectable pullup or pulldown or float. Each channel can also be used as a manual tactile switch input, DIP selectable to pull to power or ground (through a 30 ohm resistor to avoid accidental direct shorts). The latter case, it's nice that the LED indicators are there, so you know when the switches have gone bad! Integrated battery to provide 5V power to both the probe and the circuit. Or the internal PSU be used to only power the logic probe array with 5V, to make it work with arbitrary external logic. Or the external circuit can power both the logic bus and the probe, all through DIP switches and a diagram stuck on the bottom. (One of them also has a 3.3V regulator for driving the circuit with either 5V or 3.3V). I/O connections via 0.1 inch spacing headers, and a second header for optionally plugging it into an 8 channel logic analyzer. This was made before I even did PCB in CAD, but there's no good way to really design this board unless you use multiple layers. Wires are crisscrossing everywhere, and the LED array is glued over the top of the 4x quad opamp IC's to save space. It's compact for what it is.And yeah, I sometimes have squeezed a strip of label tape in there to give a tiny place to label the channels. I also made a screw on coverplate that you can just draw/write on.But plugable single LED modules (0.1" wide) are fantastic for breadboard work; no wires! Both are useful.If you want to use a multi LED bar/array like the way you're describing, there's no need for it to have 0.1" spacing of the LEDs and to plug into the board, at all. Just put it on a veroboard along with the resistors and add a pin header to it. Hot snot it to the edge of the breadboard and plug your jumpers in. One jumper to connect the common rail and one for each individual LED. My 8 channel logic probes are too big to plug into the board. They just lay next to the breadboard. Or if need be, and you're going to move this around, I glue the breadboard to a backerboard, and glue the probe to the backerboard to make them all one piece. But it's easy enough to just wire up a circuit-specific harness and be able to plug the whole unit in/out, which is what I do when using it with PCB circuits rather than breadboard.

author: rdl
author_rank: Super Contributor
timestamp: September 01, 2020, 11:04:21 pm
content: Years ago I built this dev board. The bargraph is made from 1.8 mm LEDs in a dual row pin header socket which is connected between a resistor array and the Propeller chip. The LEDs have 0.1" pin spacing and are rectangular with a small dome, so they fit side by side with no sanding needed.

author: PerranOak
author_rank: Frequent Contributor
timestamp: September 10, 2020, 04:23:57 pm
content: I ended-up just doing a cheap-arse thing on vero board!