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TJ - $99 Thermal Imager

A thumb-sized device that plugs into your iPhone / iPad / iPod Touch headphones jack and turns your iOS device into a Thermal Camera

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This project was created on 07/20/2014 and last updated 2 months ago.

TJ (Thermal Jack) powers and communicates solely through your iOS device's headphones jack (so it needs NO external battery and uses NO wireless communication). This significantly helps to reduce its cost, complexity and size.

TJ will use an Infrared FPA (Focal Plane Array) with an NETD of 0.15°K, a 4 FPS frame rate and a native resolution of 16 x 16 pixels, generating a heat map upscaled at iOS device's native screen resolution by Bicubic Interpolation.

SuperResolution (combining several low resolution frames which exhibit sub-pixel shifts into a High Resolution stil-image) is currently being evaluated.

Android and PC are supported too via an USB connection. The USB connection also allows updating the TJ microcontroller firmware. A UART connection will be offered too for low-level interfacing purposes.

TJ is a fully open source / open hardware project and a crowd-funding campaign is expected to be launched late 2014 with the purpose of entering mass-production.


Thermal Imaging technology used to be priced prohibitively outside the budget of hobbyists until recent years. Late 2012 when I started working on my 1st Thermal Imaging project, the lowest cost thermal camera available on the market was the Flir i3 (priced at $995 back then). Moreover, there was (to my knowledge) absolutely no lower cost, open-source alternative solution on the market to these expensive, proprietary devices - that mostly had to do with the high development and manufacturing costs of high/medium performance IR FPAs and lenses and with the timid availability of low cost, low performance IR modules (FPA + lens + ASIC), still not implemented in any low-cost Thermal Imager.

I was therefore highly motivated to explore the possibility of developing a Thermal Imaging platform that was low cost ( < $200 to manufacture)  and could offer sufficient performance for some of the less demanding hobbyist level tasks. That's how I've started working on Thermal Imaging devices.

A bit of background

1st attempt: Mechanically Microscanned Thermal Imager (MMTI)

I've started prototyping a device around the MLX90620BAD 16x4 IR array. The idea was to select a low-cost (implicitly low performance) IR FPA that had a low pixel FOV (2.5° x 2.6° FOV / pixel) and a satisfactory NETD (0.08°K at 1 fps in its datasheet; found out the hard way during testing that it was more like 0.4-0.5°K - still have no clue how they got to that figure). 

Then, by means of a stepper-motor controlled pan-tilt platform (that had its rotation axes centered as well as possible to the FPA's surface center in order to simplify pixel position calculations) produce a pattern of controlled sub-pixel shifts (microscanning) of the whole IR module. 

Each thermal data frame would be sequentially fed via WiFi to a connected iOS device that would form in realtime a composite high resolution image from the individual low-res frames (in the end a 176 x 44 final high resolution image would be obtained out of 121 frames of 16x4).

The prototype consisted of:

  • Melexis MLX90620BAD 16x4 IR array
  • PIC32MX795F512L based USB Starter Kit IIStarter Kit I/O Expansion Board
  • MRF24WG0MA Wi-Fi G PICtail Daughter Board
  • 3-axis stepper control board based on 3 x A3977SED (self designed / manufactured board that I had lying around since my early 20's) - naturally, only 2 axis used
  • Vexta PK246PA stepper motors that I had lying around (1.8° / step - had to use 1/8 micro stepping to obtain 0.225° steps to fulfill my sub-pixel shifting resolution demands) 
  • 3S 1600mAh LiPo battery 
  • cheap laser module (from a laser pointer) - to evaluate microscanning pattern accuracy and orientation 
  • custom pan-tilt platform (self designed / CNC manufactured) - to allow precise centering of MLX90620BAD FPA surface center to the pan-tilt platform rotation axes

Here's an image of what the Hardware Prototype of MMTI looked like and to the right is the high-res composite image 176 x 44 (formed out of 121 frames of 16x4) - 'self portrait' - yes, I stood frozen for 121 seconds :)

Conclusions drawn from the MMTI prototype testing:

  • Successfully verified the validity of the microscanning concept of this particular setup - I was actually surprised by the rather good alignment of pixels and frames
  • Sufficient spatial resolution
  • Much higher NETD than expected (specified 0.08°K at 1 fps in MLX90620BAD datasheet; found out the hard way during testing that it was more like 0.4-0.5°K - still have no clue how they got to that figure)
  • High pixel non-uniformity (although all MLX90620 are factory calibrated to a certain degree of non-uniformity); I had to implement a pre-scan calibration to get to satisfactory uniformity 
  • High measurement noise for MLX90620BAD (as sensor frame rate is increased, the noise increase too, rendering any frame rate higher than 4 FPS useless for this application) 
  • Concluded that the primary performance limiting factors of the system were: ...
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  • 1 × Omron D6T-1616L Thermal Sensor module
  • 1 × PIC16LF1459T-I/ML 8bit XLP Microcontroller
  • 1 × LP2980AIM5-3.0 3.0V LDO regulator
  • 1 × MCP6001T-I/LT Low-Power Op Amp
  • 1 × SD103ATW Schottky Array (3 diodes, isolated)
  • 5 × SDM40E20LS Schottky (Dual, Series)
  • 1 × 0473460001 Molex microUSB connector
  • 1 × DG35FP60D296L TRRS plug, PCB mounted
  • 11 × 10 uF, 0603 Ceramic Cap
  • 4 × 100nF, 0603 Ceramic Cap

See all components

Project logs
  • TJ development takes a break while new development possibilities are being evaluated

    6 months ago • 2 comments

    On Thursday 27th, Seek Thermal launched a $199 thermal camera accessory for iOS and Android. It boasts an absolutely impressive 206 x 156 microbolometer array, -40 to 330°C temperature detection range and 36º FOV. Yeah, it puts the unborn $99 TJ to shame, as well as it's more expensive competitor, the $350 Flir One.

    I must admit that the product launch timing came as a total surprise for me, even while Seek Thermal first surfaced in August declaring they've been hard at work for a couple of years already and that their camera product is in development; and I have a feeling that it came a bit surprising for the big players in the thermal imaging industry as well. What they've achieved (Seek Thermal in collaboration with Raytheon Vision Systems and Freescale) with the FPA design and manufacturing in terms of cost reduction is truly amazing!

    Now, work on TJ and it's ancestor, MMTI was directed at making thermal imaging more affordable and more open to hobbyists and everyday people. But now as a $199 thermal imager is already here, and one that sets new price/performance standards, I think there would be little incentive to buy a $99 imager that's so far-off performance-wise. 

    That being said, my motivation for continuing the development of TJ took a big hit :) Therefore, I've halted development for the time being and I'm the process of evaluating new development possibilities. I also feel there's little motivation left for fulfilling the requirements of the Hackaday Prize Finals.

    I'll be abroad for a week but I'm planning to update the project with the latest unpublished developments after I return: updated hardware, firmware and iOS software sources.

    TJ Gen2 Prototype status - as of this update

    • TJ Gen2 PCB prototypes successfully tested (both the D6T-1616L populated version and the AMG8832 populated version)
      • minor changes needed (1 added capacitor, minor pin order changes on the 12-pin expansion connector to adapt  changes on the new v900 ESP8266-based module, microUSB connector placement)
    • Added TJ firmware and iOS software support for the AMG8832 version also (in addition to D6T-1616L version support)
      • common TJ firmware for both TJ versions (TJ firmware detects the connected sensor automatically and reconfigures accordingly)
    • Added firmware and iOS software support for the ESP8266 WiFi module 
      • ESP8266 module presence on TJ 12-pin expansion header is detected automatically and TJ reconfigures for wifi-streamming instead of audio-based communication
    • iOS application UI changes
      • added temperature bar
      • tap pixel for temperature measurement
      • cleaned UI of test parameters
      • partially implemented gesture based manual ranging 

    TJ Gen2 and modules / shields hardware prototypes; iOS App. 

  • PCBs ordered!

    7 months ago • 2 comments

    After another two weeks of work evaluating and implementing different features / improvements / changes to TJ, I present you the TJ Gen2 prototype and shields: 

    • TJ Gen2 thermal imager - baseboard (lower right corner) 
      • 37.5 x 20.5 mm
      • 2 versions depending on the included thermal sensor
        • Omron D6T-1616L (16x16 FPA)    --- $99
        • Panasonic AMG883x (8x8 FPA) --- $49? 
      • audio-jack interface (iOS devices)
      • USB interface (Android / PC / Mac)
      • 12-pin shield-connector
    • BLE shield (upper left corner)
      • based on the popular $6 HM-10 module 
      • allows low-power remote connections to TJ
      • can be piggy-backed on the battery shield for battery-operation 
    • WIFI module 
      • no-shield needed (simply plug a $4.5 ESP8266-based module in TJ's shield-connector)
      • allows longer-range remote connections to TJ
      • can be piggy-backed on the battery shield for battery-operation
    • Battery shield
      • provides power to TJ through a standard 2-pin JST LiPo battery connector
      • charges LiPo batteries

    aaaand... what's that on the lower left corner? It's a...

    • Display shield
      • uses a $10, 1.5" OLED 128x128 color display
        • an <$4, 1.44" LCD 128x128 color display will also be evaluated
      • contains an uSD card slot for saving thermal images and video
      • 2 buttons
      • a LiPo charger and connector
      • Should allow TJ to become a stand-alone ultra low-cost thermal-camera :) 

    The PCBs have just been ordered today at a China fab and should probably arrive late next-week.

  • TJ versions and 'shields'

    7 months ago • 0 comments

    TJ is all about making entry-level Thermal Imaging as open and affordable as possible. With that in mind, I've started on a journey of designing a device that's not only as inexpensive as possible but one that still squeezes the best available performance, convenience and flexibility, by means of clever hw/sw co-design :)

    Affordability is paramount:

    • The $99 version (using the D6T-1616L thermal sensor) will most probably offer the absolute best thermal imaging performance available at that price-point
    • A $49-59 version (using the AMG883x thermal sensor) will also be offered for applications less-demanding performance-wise

    Convenience is another aspect that I specifically targeted:

    • You have an iOS device (iPhone, iPad, Ipod Touch) -> You simply plug TJ in your headphones jack and it's ready for use
    • You have a device with an USB port (Android smartphone / tablet with USB OTG; Windows tablet, PC; Mac) -> You connect TJ to the USB port using a microUSB cable and it's ready for use

    How about Flexibility:

    • You want to connect remotely to TJ or want to connect to more than one device (think room occupation detection / people-counting applications etc.) 
      • TJ will have a small extension header that you can plug a 'dirt-cheap' $4.5 WIFI module like this ESP8266-based one (thanks Hackaday for the article on this module!)
        • just stack the WIFI module, apply power on TJ's USB connector / external powering pins or use a battery shield and it's ready to stream thermal data


      • A Bluetooth Low-Energy shield based on the rather popular HM-10 $6 BLE module will also be designed and made available for low-range / low-power consumption interfacing

    • You want to power TJ by battery?
      • A simple shield containing a LiPo charger IC, a power switch, an LED and a standard battery connector will be designed and made available 

View all 8 project logs


ap2006 wrote 4 months ago point
So, I'm new to this community... Do I have to build the Thermal Imager or could I buy it?

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Marius Popescu wrote 4 months ago point
Well, for the time being the only way is to build it yourself. I really hope that one day you'll be able to buy it! :)

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Bogdan Chihaia wrote 5 months ago point
Hello Marius Popescu, I'm very interested in your work, and I was wondering if you could help me with a few tips. I'm a biomedical engineer and I am planning to start developing an IR scanner for early skin cancer detection on a low budget. Could you help me?

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Marius Popescu wrote 5 months ago point
Hi Bogdan. You should be looking at higher resolution, lower NETD sensors for your intended application. I'm sorry to discourage you but I don't think it can be exactly low budget.

Sure, you can drop me an e-mail with your questions and I'll do my best to help.

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Bogdan Chihaia wrote 5 months ago point
thanks a lot! just give me your email adress, please...

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Marius Popescu wrote 5 months ago point
Drop me an e-mail at (yep, it's an alias so i need not worry about spambots :p)

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Bogdan Chihaia wrote 5 months ago point
thanks a lot!

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Pure Engineering wrote 7 months ago point
you gotta check out the flir lepton:

its a 80x60 thermal module for about $250.

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Marius Popescu wrote 7 months ago point
I'm fully aware of the Flir Lepton since its announcement! :) Though, different price-point, different performance.

I'll be keeping a close-eye on the groupgets campaign. Maybe I'll join too :)

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Jasmine wrote 8 months ago point
Hello Marius Popescu, now is the time to add a few more details to your project to give it the best chance of going through to the next round of The Hackaday Prize.

By August 20th you must have the following info on your project page:
- A video. It should be less than 2 minutes long describing your project. Put it on YouTube (or Youku), and add a link to it on your project page. This is done by editing your project (edit link is at the top of your project page) and adding it as an "External Link"
- At least 4 Project Logs
- A system design document. Please highlight it in the project details so we can find it easily.
- Links to code repositories, and remember to mention any licenses or permissions needed for your project. For example, if you are using software libraries you need to document that information in the details.

You should also try to highlight how your project is 'Connected' and 'Open' in the details and video.

There are a couple of tutorial video's with more info here:

Good luck!

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Marius Popescu wrote 8 months ago point
Hi Jasmine,
Thanks for the reminder!
I'm working hard behind the scenes. The following days it'll become more visible :)

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Rahul Mascarenhas wrote 8 months ago point
Great project!! What are the average values of current/power that the power harvesting circuit manages to output?

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Marius Popescu wrote 8 months ago 1 point
In the current setup I'm using ~5.5mA @3.3V. I haven't characterized the maximum output yet.

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peter jansen wrote 8 months ago point
Hi Marius,
Great project! If you don't mind my asking, where are you sourcing your AMG8831/32s from? It seems like every distributor is fresh out of them. Thanks!

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Marius Popescu wrote 8 months ago point
Hi Peter,

Thanks! Yeah, I've just checked Digikey now and indeed their stock is 0... weird. But you can still buy this dev-kit if you need it for prototyping only:

I've only needed 1 piece for evaluation and the unit was ordered directly from Panasonic Japan through Avnet Abacus (Europe). In Europe it's much more complicated to source than in US (due to it's Dual Use nature...)

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peter jansen wrote 8 months ago point
Thanks! I asked Digikey when they'd expect them back in stock and they sent me a quote for 1000 with an expected delivery of around December, so I'm guessing regardless of their characteristics these likely wouldn't be a good choice for either of us. I'll let you know if I hear differently or find a source!

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Erik Beall wrote 8 months ago point
Hi Marius,
very nice project, and the image you created with your micro-scanned MLX90620 is amazing for that sensor. Scanning and stitching with good spatial accuracy is impressive!

I saw the comment about the price - I actually paid $1200 for my first 64x62. I do have some help to get the price down and we will be at-cost. Also the lens is probably different (we are using Germanium but they can do many different lenses - they have an in-house lens designer).

Good luck with your project! Using a audio hijack interface is a great idea to get power and data.

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Marius Popescu wrote 8 months ago point
Hi Erik,

Thanks for your appreciation!

Yeah, I was really intrigued by HemaImager's asking price so I couldn't help but ask Heimann Sensor for a quotation :)

Anyway, if you can sell considerably under Flir One asking price and still make a healthy profit, then you got a winning ticket there!

Wish you all the best with the Kickstarter campaign! I'll be following closely :)

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Noman wrote 8 months ago point
Thanks, yes that may be the case.

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Noman wrote 8 months ago point
Thanks for enlightening. Please do share prices once you get from Heimann. If they sell it for $1018 how Hema-Imager can sell at $225 including everything!

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Marius Popescu wrote 8 months ago point
I will post a comment as soon as I have info on that.

Well, volumes is one way, but it sounds a bit too good to be true... If it is, good job to them!!!

I'll do my research! :)

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Marius Popescu wrote 8 months ago point
I've just been on the phone with a Heimann Sensor representative and I've got the following quotation:

HTPA 64x62 (60x60 effective size) with L10 F0.80 (40.2 x 39.0 FOV) Ge Lens (the configuration that the Hema-Imager uses) was quoted at 146 EUR (195 USD) @1000units

So they're either getting a much better deal or they're probably selling on loss, at least for the Kickstarter campaing :)

In the kickstarter they also say that for the first 50 units they've been offered a special price, though not for the whole 800 units.

For the 82x62 the representative couldn't give me a quotation at this time.

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Noman wrote 8 months ago point
I just have read about Heimann HTPA 82x62 sensor. It looks great in specs but am not sure about price. Also there is a new kickstarter campaign going on namely Hema-Imager asking for $225 for 64x62 sensor device.

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Marius Popescu wrote 8 months ago point
Thanks for the info on the Hema Imager! I was unaware of it.

I am familiar with Heimann Sensor IR Array products and followed their progress for a long time, although I'm still puzzled how they're able to get the 64x62 IR arrays for so low...

There's a doc. on Boston Electronics website that quotes the 64x62 IR Array at $1018:

This makes me so curious that I'll probably give Heimann Sensor a call later today to ask for a quotation on the 64x62 and the 82x62 :)

By the way the 82x62 developed by Heimann Sensor is mass-produced (and also sold) by Bosch Semiconductor as SMO130:

Seems like the same kind of deal they have with Melexis for the MLX90620 (originally developed by Heimann Sensor)

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Noman wrote 8 months ago point
Cool. Marius, congrats for working out such low cost thermal imagery. I wonder why you have not opted for BLE/Techbasic way for IOS?

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Marius Popescu wrote 8 months ago point
Thank you! I went this way to make interfacing as cost-effective as possible. Another reason is convenience (needs no battery; you plug it in and it's ready for use)

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radu.motisan wrote 8 months ago point
Very promising results, congrats on the project and looking forward to see more!

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Marius Popescu wrote 8 months ago point
Thanks, Radu! I better not disappoint then :)

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Mike Szczys wrote 8 months ago point
Wow... an order of magnitude cost reduction for this tool, fantastic! Can't wait to see where you end up with this one since the preliminary results are very promising!

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Marius Popescu wrote 8 months ago point
Thanks a lot for your kind words Mike!

Stay tuned for the Gen1 prototype (hopefully early August). It's expected to offer much better performance!

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David Cook wrote 8 months ago point
I'm giving you a skull just the courage to post photos of your gnarly free-form soldering of SMT components!!

Seriously, though -- a very interesting project. Best of luck to you!


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Marius Popescu wrote 8 months ago point
Thanks, David!

Well, that's how it looks like when you decide on a Friday night that you need a hw prototype :)

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