Thank you for sharing the knowledge. Really cool to learn about. Also I hope you don't mind my saying but your voice is really calming and lovely to listen to. 🙂
Loved that you showed the steps of the design/engineering process. I've been subbed since you did collab with Steve Mould, this is probably my favorite video so far, partially because it is so candid, thanks, good luck in designing more discrete logic setups!
Hey Seb, I really enjoyed your video, love how you tackle problems :) I have one thing you may consider: When dealing with interlock circuits you should aim for a failsafe design. In your circuit a single photo-relay is in charge of connecting / disconnecting the interlock lines of the laser. A photo-relay uses MOSFETs to achive this. A common failure mode for them is to fail as a short circuit. I'm not sure if photo-relais are susceptible to a "fail short" scenario, but if this happens you could hit the E-Stop button as hard as you want, your laser would still be enabled (ignoring that the status LEDs would indicate otherwise). The whole SR-Latch may also fail and cause the photo-relay to be turned on regardles of the E-Stop Button. Companies like PILZ build safety relays with a START/RESET circuit builtin. Internally these relais use two relais in series to ensure the circuit is disconnected even if one of the internal relais fail closed. Further these dedicated safety relays got all the necessary certification to comply with interlock/estop circuits. Downside: These safety relays are not cheap. What do you think about the following to make your circuit a little safer: These E-Stop Buttons often can fit more than one switch module which get actuated at the same time. What about using two modules: One is used to feed your circuit like you explained in the video. And another N/C Module is connected in series with your photo-relay. So if you hit the E-Stop button the lasers interlock circuit gets disconnected by the second switch module and, when everything works as excepted, by the photo-relay as well. In this scenario you would only lose the SET/RESET functionality instead of the whole E-Stop functionality. Which is a big win. Looking forward to your opinion in this :) P.S.: I'm not an expert by any means.
Love the enthusiasm that you bring to the subject. Makes me sooo to want to buy a laser system which is complete impratical for me :-) You are doing a great job of lifting this subject, promoting safety and generally creating great content.
"Geeky nerdy content" is 100% my jam! I didn't know that lasers shouldn't be power-interrupted until you said, but I was then expecting it to be because because of a risk of damage to components; the "scanners go berserk" mode wasn't what I guessed, but I can see how that could be really serious!
@@seblee Yes. If the power fails then the switch mechanically disconnects. If the power returns then an 'On' button needs to be pressed to re activate the circuit. It also works with the big red button. Pressing that interrupts the power and disconnects the circuit in the same way. Pressing the 'ON' button re activates the circuit. All done with a relay and self powered from the supply circuit. For your application it might still need an external power supply unless there is enough power in the laser's emergency stop circuit to keep a small relay coil active all the time it is in use.
@@Maker_of_Things oh well I'm using a photo relay so it's similar at least in its function, if not its execution. The interlock in the laser is super low voltage though (usually 5v) so doesn't need a massive relay.
@@seblee I think you are doing it in a better way. I don't (yet) understand all the electronics and logic stuff beyond basic principals and so my mind reverts to very old school electro-mechanical solutions. With so little power available you wouldn't want to waste it keeping a couple of relay coils energised. Also more chance of them failing prematurely when you least want it to. Your simple pcb would be easier and cheaper to swap out, and be more reliable in the long run, I expect.
Is there a way that the button can be pressed so it turns off the laser, but doesnt lock down? Maybe having that start button is good for situations where you hit it quickly but not fully down, and that might happen?
@@seblee Really confusing. You mention it's a livestream in the beginning, but there's no chat replay, it also said ’uploaded‘ not ’streamed at‘ and yet you still read comments. In conclusion: About every five minutes, I changed my opinion on whether that was a livestream or not
