https://community.element14.com/products/pcbprototyping/Join members as we design, prototype and fabricate printed circuit boards, for fun and for practicality!en-USTelligent Community 12https://community.element14.com/products/pcbprototyping/b/pcb-blogs/posts/ninja-reflow-part-2-reverse-engineering-the-pcb---mains-poweredFri, 10 Apr 2026 18:03:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:e6a02f7e-ab52-41c8-81e4-41d58d986bb7Fred27So, after deciding that I would update a Ninja SP101 oven / air fryer to act as a reflow oven, the first step was to reverse engineer the PCB. I needed to know what pine I had to toggle to turn on the elements and what I had to read to get a temperature reading. The components I needed to interface to were as follows: Three upper heating elements that can be separately controlled On set of three lower elements that are all switched at once A main fan for the fan oven bit A light inside the oven A PCB fan for cooling the triacs A thermistor for taking oven temperature readings A thermistor for taking temperature readings from the triacs A front panel which use a TM1629D to manage the LED display and buttons A rotary encoder for the main button Unknown to me at first, but there's also an accelerometer to tell if the oven's upright The PCB was luckily a fairly simple single-sided affair with a few jumped links. It was simple enough although the SMT components were tightly packed and it could be tricky to see if some pads were connected or just close together. This is a section of the board. I started off on the main bit - controlling the elements. Tracing the high voltage control circuitry back to the relevant PCB pin wasn't too tricky. It just involved peering at traces under the microscope, using a continuity tester, and a bit of common sense. I could see 3 triacs for the upper elements. Each one had an optoisolator. Nearby was a transistor and resistor. These led back to 3 pins on the STM32 microcontroller. Not too tricky. Similarly there were two relays. One seemed to be the first thing in the path of the mains power. The second seemed to connect to the lower elements. I guessed that the first isolated everything for safety reasons and the second was for the lower elements. The path back gto the microcontroller for the lower elements was the usual flyback diode, transistor, resistors, etc. The main power one seemed a little more complicated but did eventually go back to a pin. After guessing the pins the first thing I did was some basic code to switch the elements. I had some success. One of the relays (for the lower elements) clicked in a very satisfying way, but the main one refused to engage. I suspect the triacs were working but with the primary mains power cut off it was hard to tell. From the slightly more complicated circuitry between the pin and the relay, I suspected that something more than just a digital output was needed. It would be terrible if something went wrong and things were stuck on. My money was on a pulse train, but I suppose an anaolg output in a specific range was a possiblility too. I decided that spending a bit on a spare board from eBay would be useful. It woudl mean I could revert things if it went wrong and also could probe how things should work. In the end it turned out that a 5kHz square wave was needed. A bit of modified code later and I could control all the elements and also the main fan and light via the SPM32's GPIO. Whilst doing this I decided it would be safest to use a logic analyser and a laptop running on battery power. A handheld oscilloscope that I got from Element14 also came in useful. It seems that however the 3.3V DC (also 12V and 5V) is generated, the ground floats at about 80V above earth. Good job I didn't use a mains powered oscilloscope before checking! After working out the mains powered side of things, I found a good point to power the board via 5V so could work on the logic level side of things in a bit more comfort. It's not nice typing on a laptop knowing any metal parts might feel a little spicy!stm32reverse engineeringreflow solderinghttps://community.element14.com/products/pcbprototyping/f/forum/56836/protoboard-templates/234916Thu, 09 Apr 2026 20:30:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:fd5f90b5-a5e5-4f5d-9d6b-564cb70a9b0fcolporteurYour profile points count suggests you are new to the community. Welcome. You will fit in well here, making an offering of your own work product. A Three-Way Prototyping Board for Awkward Through-Hole Components the link is for the ultimate perf board template. The author of the board does some pretty amazing work. I've benefited a number of times when he has shared his work product. Seanhttps://community.element14.com/products/pcbprototyping/f/forum/56836/protoboard-templates/234915Thu, 09 Apr 2026 20:28:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:0880a0a3-cbff-4472-8361-e88c06ce6a7fDABWelcome to the community. Feel free to as questions, we all learn something new everyday.https://community.element14.com/products/pcbprototyping/f/forum/56836/protoboard-templates/234906Thu, 09 Apr 2026 13:07:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:e258e0e6-2f64-476e-9775-e99949709ee0robogaryWelcome to E14 and the idea share. Thats a great idea to avoid having to think and wire at the same time, get it right the first time. In spite of years of practice, we all still make mistakes wiring prototypes and let the smoke out :-)https://community.element14.com/products/pcbprototyping/f/forum/56836/protoboard-templates/234899Thu, 09 Apr 2026 09:27:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:2b1fa868-0596-4b10-b4af-2b6302d1c48aacdc90Hello hope you enjoy your time here and you will learn stuff, The pattern you have drawn reminds me of the vero board i used to build A 8bit computer using wire wrap. Do you have any projects in mind like interfacing to the real world or do just want to learn about electronicshttps://community.element14.com/products/pcbprototyping/f/forum/56836/protoboard-templatesThu, 09 Apr 2026 00:26:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:3e13bd0c-2ae5-4a5e-bbbe-9604c8fa7d73TekkromancerHi all! I'm fairly new to electronics. To aid in my journey, I created some printable templates to help me plan out my circuits on protoboards on good old pencil and paper. So far, I just have two, but I'll certainly add more as I continue. I'm happy to share them with the community in the hope that others will find them useful. https://drive.google.com/file/d/1D_SknoozM5y2BAGld1N10K4CS7UIFK_e/view?usp=drive_link Cheers!templateprotoboardhttps://community.element14.com/products/pcbprototyping/b/pcb-blogs/posts/reprogramming-an-air-fryer-for-reflow-solderingSun, 29 Mar 2026 16:35:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:45d773ed-f91d-4f41-95b0-0b7ed9af3e52Fred27As was browsing EEVBlog a while ago... (I know. It's great here, but I sometimes like go look elsewhere too.) Anyway, I was browsing EEVBlog and came across an interesting post where someone had taken a Ninja SP101 domestic air fryer / pizza oven and replaced the PCB to use it for reflow soldering. https://www.eevblog.com/forum/projects/ninja-smt-reflow-oven/msg6103711/#msg6103711 I already have a small mini-oven that's been adapted with an external controller. However I liked the way he'd gone about this - especially the way the original display and controls had been retained. I put a search for the same model on eBay and thought that it might make a nice project if a cheap one came up. Well, what do you know - a brand new one that had been dropped and dented came up for only £25, so I went for it. I fully intended for it to ba a back burner project and for it to perhaps never get finished, but once it was in the gagade I decided to give it a poke. The original project was a total PCB replacement, but I was interested in a bit of reverse-engineering and to see if it was possible to re-use the existing PCB and replace the firmware. The existing board consists of an STM32F031 microcontroller. This controls some relays, triacs, fans, and an internal light. It connects to a front panel with some 7-segment displays, a rotary knob and a few buttons. I know from the other project that it uses an NTC thermistor for temperature measurement, but that this reacts a little too slowly. If this is going to work then I will need to interface with all these components and also see if I can add a thermocouple. The first thing I did was to hammer out some of the dents and get it looking respectable, if not exactly perfect. Apart from a few scars and a broken doo rhandled it did indeed work just fine. The next thing I did was to see if I can connect to the onboard microcontroller. I found an old STM32F0Discovery board from many years ago to use as a ST-LINK and decided to see if the usefully provided debug header would reveal anything. As the oven was running from mains power I ensured my laptop was running on battery to prevent any ground loops. STM32CubeProgrammer did indeed reveal an STM32f03x microcontroller but it had Read Out Protection (level 1) enabled. It looked like it was possible to reset the Read Out Protection bits using the programmer so I decided to give this a try. It worked! However I shouldn't have been surprised to see that it also erased the on-board firmware. Oh well - no going back now. My air fryer is getting a new purpose in life or it's being left for dead. My reverse engineering journey is about to begin... On to Part 2stm32reflow solderinghttps://community.element14.com/products/pcbprototyping/f/forum/56793/led_matrix_mosfet_driver_10x10/234625Thu, 26 Mar 2026 21:38:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:0fc99a67-edbb-4eb1-92d9-6842efe945efbattlecoderNice. I love transistor-based project, so I like your approach. Having said that, and echoing what @vmate already said; for this amount of LEDs it's normally desirable to have a higher level control interface with more features. There's one controller I like a lot; the MAX7219 8x8 driver. It has a serial interface, so you don't need to worry about multiplexing or toggling LEDs individually, just feed the pixel data to the IC and will do the multiplexing for you. It also handles the LED current, which you can set externally, and it can also do BCD decoding if you use it to drive 7-segment displays instead of LEDs... And all of that with just 3 wires. Now, it's only 8x8, but it can be daisy chained to extend the display resolution without increasing the pin count. There are advantages to directly addressable LED matrices like yours though, like the immediate response time of each LED, the fact that you can refresh the LEDs non-sequentially, and the ability to control them with analog or mixed logic, but I think those are slightly more niche applications so I expect that most people would probably be looking for something that frees the microcontroller from toggling the LEDs one by one.