> **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 # Adafruit SCD-40 - True CO2, Temperature and Humidity Sensor - STEMMA QT / Qwiic **Type:** Product page · **SKU:** ADA5187 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia) **Page:** https://core-electronics.com.au/adafruit-scd-40-true-co2-temperature-and-humidity-sensor-stemma-qt-qwiic.html ([markdown](https://core-electronics.com.au/adafruit-scd-40-true-co2-temperature-and-humidity-sensor-stemma-qt-qwiic.html.md)) Take a deep breath in...now slowly breathe out. Mmm isn't it wonderful? All that air around us, which we bring into our lungs, extracts oxygen from... ## Pricing - **Price:** $85.35 (inc GST) — $77.59 AUD, exc GST - **Quantity discounts:** 10+ $75.26 (exc GST) · 50+ $73.71 (exc GST) ## Availability & dispatch - In stock, ships same business day if ordered before 2PM (Australia/Sydney). - We can dispatch 1 today, and up to 500 more in 7–12 days. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=ADA5187:1` (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/ADA5187:1.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 ## Description Take a deep breath in...now slowly breathe out. Mmm isn't it wonderful? All that air around us, which Adafruit bring into Adafruit's lungs, extracts oxygen from and then breathes out carbon dioxide. CO2 is essential for life on this planet Adafruit call Earth - Adafruit and plants take turns using and emitting CO2 in an elegant symbiosis. But it's important to keep that CO2 balanced - you don't want too much around, not good for humans and not good for Adafruit's planet. The SCD-40 is a photoacoustic 'true' CO2 sensor that will tell you the CO2 PPM (parts-per-million) composition of ambient air. [Unlike the SGP30, this sensor isn't approximating it from VOC gas concentration](https://core-electronics.com.au/adafruit-sgp30-air-quality-sensor-breakout-voc-and-eco2.html) - **it really is measuring the CO2 concentration**! That means it's bigger and more expensive, but it is the real thing. Perfect for environmental sensing, scientific experiments, air quality and ventilation studies, and more. [Compared to the illustrious SCD-30](https://core-electronics.com.au/adafruit-scd-30-ndir-co2-temperature-and-humidity-sensor-stemma-qt-qwiic.html), this sensor uses a different measurement technique, which allows it to be much smaller. The overall data quality should be very similar, however. Like the SCD-30, this sensor has data read over I2C, so it works very nicely with just about any microcontroller or microcomputer. There's both Arduino and Python/CircuitPython code so you can get started in a jiffy. There are two variants of this sensor - the SCD-40 and SCD-41 - The **SCD-40** is lower cost, and is perfect for indoor/outdoor air quality and CO2 measurements. It has a range of **400~2000 ppm** with an accuracy of ±(50 ppm + 5% of reading) - The **SCD-41** is more expensive, and while it can definitely be used for air quality, it's wide range means its best used for industrial or scientific CO2 measurements where the ppm can get very high. It has a range of **400~5000 ppm** with an accuracy of ±(40 ppm + 5% of reading) Nice sensor, right? so they made it easy for you to get right into your next project. The sensor is soldered onto a custom-made PCB in the[ **STEMMA QT** form factor](https://core-electronics.com.au/search/?q=stemma%20qt%20sensor), making them easy to interface with. The [STEMMA QT connectors](https://learn.adafruit.com/introducing-adafruit-stemma-qt/what-is-stemma-qt) on either side are compatible with the [SparkFun Qwiic](https://www.sparkfun.com/qwiic) I2C connectors. This allows you to make solderless connections between your development board and the SCD-4x or to chain it with a wide range of other sensors and accessories using a [**compatible cable**](https://core-electronics.com.au/search/?q=stemma%20qt%20cable). This sensor can run from 3.3 to 5V but it's more important for it to have a quiet power supply with low ripple, than any particular voltage. For that reason Adafruit have added a 3.3V regulator and level shifters: when connecting to a 5V microcontroller like an Arduino UNO the 5V supply is often shared with other electronic components that add noise. The onboard regulator will keep the voltage nice and quiet. For advanced hackers, they can cut/solder the back traces to change whether the regulator is enabled and what I2C logic level is desired. **For libraries, example code, wiring diagrams, datasheets, and more, check out the learn guide!** ## Technical Details **SCD-40 Specifications:** - Photoacoustic CO2 sensor technology - Integrated temperature and humidity sensor - Measurement range: 400 ppm – 2000 ppm - Accuracy: ±(50 ppm + 5 % of reading) - Current consumption: 17 mA (meas. rate = 5 s) / 0.5 mA (meas. rate = 5 min) - Fully calibrated and linearized - I2C digital interface address 0x61 - Sensor Element Size: 10.1mm x 10.1mm x 6.5 mm - Product Dimensions: 25.5mm x 22.8mm x 7.7mm / 1.0" x 0.9" x 0.3" - Product Weight: 2.8g / 0.1oz ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/i/m/image_777.jpg)