Making the Safe-T-Flow… surface mount soldering with an ardunio & robot controller skillet

Making the Safe-T-Flow, a way to control the heat on a skillet to make surface mount electronics… this is part one (m4v).

Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here:

Join Adafruit on Mastodon

Adafruit is on Mastodon, join in!

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Join over 36,000+ makers on Adafruit’s Discord channels and be part of the community!

CircuitPython – The easiest way to program microcontrollers –

Maker Business — “Packaging” chips in the US

Wearables — Enclosures help fight body humidity in costumes

Electronics — Transformers: More than meets the eye!

Python for Microcontrollers — Python on Microcontrollers Newsletter: Silicon Labs introduces CircuitPython support, and more! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Guardian Robot, Weather-wise Umbrella Stand, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — #NewProds 7/19/23 Feat. Adafruit Matrix Portal S3 CircuitPython Powered Internet Display!

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at !


  1. I’ll be interested to see how you handle the feedback loop in software because of the extreme lag in response from the skillet: it’s not like a position sensor on an actuator where you start moving it and stop when the feedback says you’ve got to where you want to be. Overshoot could be a real problem.

    Neat project!

  2. Actually, thinking about it a bit more I’d have taken a totally different approach. I *love* the engineering in your servo-controlled temperature knob, but what I’d have done is put a mains-rated relay in the supply line (could even be just an X10 module if you don’t want to touch mains) and turn the skillet control to max. Then use the temp sensor as input and just turn the skillet on and off to stabilize it around the target temperature, since that’s all the in-built temperature control does anyway. Attempting to manipulate the built-in control puts you an additional step removed from the output you’re measuring so you have to deal not just with the hysteresis of the heater coil and temperature sensor but also the inbuilt controller itself.

  3. most people do a relay/triac with thermocouple type thing. i wanted to try this out.
    reflow isn’t that delicate, theres a bit of leeway. i’ve been doing ‘hand reflow’ by watching my multimeter and turning the knob slowly. now just cuz i’m doing something don’t mean its the right thing to do. im going to try this out & report back. 🙂

  4. Since you’re already using an arduino, there’s temp control software already written for it to control a solid state relay.

  5. Awesome! Any chance of getting the designs up on Thingiverse? I do a lot of skillet reflows and adding temperature control to the mix would rock.


  6. @chow if this dont work, ill put a relay/triac in the mix!

    @zach, ya this will go on thingiverse maybe later today. dont forget, this is probably not the ‘right’ way to it. then again, someone else may have use for this design 😀

  7. Nice video. Always interesting to see the thought processes people are going through…

    Also jealous of your Epilog laser and the nice space that adafruit occupies. I really like the skylight.

  8. You might check out this instructable. He puts together a uC hot-plate controller that’s not quite as nasty as some AC solutions that you may not want to touch (literally). And it’s even ATtiny2313-based.

    I’m not personally a huge fan of steampunk/servopunk solutions when a pure electronic one is the more natural fit, but if you added some drawdio-style audio to match the servo motion, it’ll be huge with kids… 🙂


  9. im heading towards using an SSR, i bought one for $10. i found an SSR chip from mouser but its like $6 and after the heatsink and protection circuitry its about the same price.
    anyways itll show up soon. i hope is zero crossing, if not i can pretty easily make the 0-cross circuitry.

  10. Shameless plug: if you decide to go the PID control route, using the Arduino PID Library would probably be easier than modifying the coffeeTronics code.

  11. @br3ttb thats neat! is it under an OS license? I looked at the code but didn’t see any licensing notes. the coffeetronix is NonCommercial and I want to use this to reflow boards for my kit business 🙂

  12. Sorry I didn’t specify a license in the code. the files are hosted on google code, and there I specified GPLv3 (

    I’ll have to add a comment in the code itself for the next version. at this point that’s the only “bug” I have to fix before the library leaves beta. let me know if you find anything else.

  13. Understanding it’s relative, I never though household circuits as HV, but an interesting solution to deal with something that you said you where uncomfortable with. I never knew an electric skillet could be used to reflow, so I may get around to trying SMD projects. Garage sale season is around the corner, if the $ store doesn’t carry inexpensive electric skillets. Thanks for taking the time to detail your projects, and posting them to the web.

  14. Sorry to resurrect an old thread, but here’s what I use to control 120VAC when I don’t feel messing with HV wiring:

    It’s a photoelectric lamp control. I buy them at my local hardware store. You plug it into a standard outlet and then plug your load (up to 300 watts) into it. I glue a rubber grommet over the photocell, then glue a green LED into the grommet. LED ON = AC OFF.

    Don’t laugh – I hatched a number of button quail eggs in an incubator improvised from a crock pot using this and a simple diode temperature sensor circuit.

Sorry, the comment form is closed at this time.