> **Source:** Core Electronics is an Australian maker-electronics retailer and manufacturer based in Newcastle, NSW, run by a team of makers and educators. We design and manufacture our own product lines (PiicoDev, CE originals) and are official retailers for iconic maker and industrial brands including Raspberry Pi, Arduino, Adafruit, SparkFun and DFRobot. Orders ship Australia-wide from our Newcastle warehouse. Prices are in AUD and include GST. Pricing, stock and dispatch on this page are generated from the store's live catalog. Full machine-readable index: https://core-electronics.com.au/llms.txt # Bi-Color (Red/Green) 24-Bar Bargraph w/I2C Backpack Kit **Type:** Product page · **SKU:** ADA1721 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia) **Page:** https://core-electronics.com.au/bi-color-red-green-24-bar-bargraph-w-i2c-backpack-kit.html ([markdown](https://core-electronics.com.au/bi-color-red-green-24-bar-bargraph-w-i2c-backpack-kit.html.md)) What's better than a single LED? Lots of LEDs! A fun way to make a small linear display is to use two 12-bar Bi-color bar-graphs. However, this LED bargraph is 'multiplexed'... ## Pricing - **Price:** $18.95 (inc GST) — $17.23 AUD, exc GST - **Quantity discounts:** 10+ $16.71 (exc GST) · 50+ $16.36 (exc GST) ## Availability & dispatch - Available with a lead time — expect dispatch between Aug 21 and Aug 25. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=ADA1721:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/ADA1721:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## Description What's better than a single LED? Lots of LEDs! A fun way to make a small linear display is to use two 12-bar Bi-color bar-graphs. However, this LED bargraph is 'multiplexed' - so to control all the 48 LEDs you need a lot of pins. [There are driver chips like the MAX7219](https://core-electronics.com.au/max7219cng-led-matrix-digit-display-driver-max7219.html) that can help control a bar-graph/matrix for you but there's a lot of wiring to set up and they take up a ton of space. Here at Adafruit Adafruit feel your pain! After all, wouldn't it be awesome if you could control a colorful bargraph without tons of wiring? That's where this adorable LED bar-graph backpack comes in. Much like Adafruit's 8x8 and 7-segment backpacks, this backpack pairs perfectly with Adafruit's bar-graphs and manages all the LED control and multiplexing. The backpack uses a driver chip that does all the heavy lifting for you: It has a built in clock so it can multiplex the display. It uses constant-current drivers for ultra-bright, consistent color, 1/16 step display dimming, all via a simple I2C interface. The backpack comes with address-selection jumpers so you can connect up to eight of these bar-graphs on a single I2C bus. You can also mix-and-match the bar-graph breakout with Adafruit's other types of I2C LED backpacks. The product kit comes with: - A fully tested and assembled LED backpack stick - [Two 12-bar bi-color bar-graphs](https://core-electronics.com.au/bi-color-red-green-12-led-bargraph-pack-of-2.html) - 4-pin header A bit of soldering is required to attach the matrix onto the backpack but its very easy to do and only takes about 5 minutes. Of course, in classic Adafruit fashion, We also have a detailed tutorial showing you how to solder, wire and control the display. They even wrote [a very nice library for the backpacks so you can get running in under half an hour, displaying images on the matrix or numbers on the 7-segment](https://github.com/adafruit/Adafruit-LED-Backpack-Library). If you've been eyeing matrix displays but hesitated because of the complexity, his is the solution you've been looking for! Bi-Color (Red/Green) 24-Bar Bargraph w/I2C Backpack Kit (4:37) ## Technical Details - Bargraph Dimensions: 10mm x 30mm ( 0.4" x 1.2") - 7mm (0.3") thick - [Lots more LED details including dimensions, pinouts, etc in the datasheet, this is the Common-Cathode model KWL-R1230CDUGB](https://core-electronics.com.au/attachments/localcontent/KWL-R1230XDUGB_12607d54ef7.pdf) - Board Dimensions: 13mm x 101mm (.5" x 4") - Chipset: HT16K33 [Datasheets, schematic, EagleCAD PCB files, and Fritzing available in the product tutorial](https://learn.adafruit.com/adafruit-led-backpack/downloads) ![](https://core-electronics.com.au/attachments/localcontent/rohs_icon_8216055e11.jpg) ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/1/7/1721-00.jpg)