After acquiring a used Cubex Duo 3D printer, I discovered the heated-bed did not actually heat. The PID controller for the unit appeared to be functional and the relay could be heard actuating, however upon testing with a DMM I found the relay to not be contacting. Opening the PID controller revealed a cheapo chinese relay which made me think if there was a better way: an SSR would be quieter (silent) and more reliable than a mechanical relay in the given application. With the help of Scott Walde I sourced an SSR and tested the PID output with a resistor and LED to prove an SSR would work. I drilled and tapped a hole to attach the SSR to the PID enclosure and applied thermal paste; the enclosure is the heatsink for the SSR. I bypassed what was the chinese relay and used the PID connections to wire up the now externally mounted SSR. It works perfectly and any concern on heat dissipation of the SSR is nullified in practice: the heat from the SSR is only enough to take the chill off the metal enclosure, not warm it up.
The sous vide controller is beginning to take better shape than the prototype on the breadboard. Note, this one still has a fully configurable analogue stage. The wheatstone bridge and the op-amp gain can be changed by swapping out resistors.
The meals have also progressed beyond soft-boiled eggs.
I just spent the past two days helping out at our booth at Spectrum 2016. Spectrum is a triennual show put on by the U of S College of Engineering students. The people attending on Thursday and Friday tend to be predominantly school field trips. It was great to meet kids who were enthusiastic about making things.
The show continues on Saturday and Sunday, so please come visit our booth and chat with us about making things and maker culture.
Our display consists of a variety of projects that Techworks members have made.
Of course, there is a ton of other cool stuff to see, so budget at least a couple of hours to look around. Kilobots XXXII will also be holding their event in the Hardy Lab on Saturday and Sunday, so if that’s your thing, make sure to budget even more time to watch the mayhem.
I have been talking about this for ages… threatening to build it… even ordered parts. But, it wasn’t until a couple of weeks ago when Drew brought his Sansaire over and cooked some eggs for us that I finally got the motivation to start work on this project.
There are 101 ways you could do this. I’m going for cheap. My temperature sensor is a super-cheap PT100 PTC sensor. I am running it in a wheatstone bridge connected to a differential amplifier tuned to get the best resolution out of the temperature range I’m interested in. (49C – 74C) The output of that goes to a Nano clone, which currently only turns a Solid State Relay on and off. (I plan to use PID in the future) The relay turns a slow cooker on and off. This tiny one really isn’t hot enough, but I’m giving it a try today.
I am monitoring the whole thing over the USB/Serial port with a quickly hacked together windows application. Future plans including adjusting the setpoint and tuning the PID from this application.
So, in about an hour, I should have some perfectly cooked eggs!
It worked! These were cooked to 64.5C for one hour.
We had five soap-makers and two helpers (plus me) at the soap workshop last night. This was a very good size, I think. We had a variety of ingredients. In addition to the usual coconut oil and olive oil, we used lard, cocoa butter, flaxseed oil, lanolin, and perhaps a few more I’ve forgotten. I’m looking forward to hearing reports on how the soaps turned out.
I wanted to wait until I was finished before making this post. Sadly, there has been an unexplained delay with shipping my circuit boards. So, since my job is keeping this webpage moving with new projects, here it is.
I ordered some 2.3″ 7-Segment LEDs from Aliexpress for the purpose of making a countdown timer for the SCRC Kilobots arena. The plan was to have it ready for the big Kilobots XXXI event Sept 20th and 21st, 2015.
Since time was getting tight, I went ahead and designed a circuit board and sent it away for manufacturing. (Sent the files, that is.)
I did this in the wrong order, really, since I hadn’t even tested the circuit yet. Over the Sept long weekend, I spent a bit of time and built the circuit on a breadboard to test. Fortunately, it worked.
(Yes, one of the segments is out in that picture.)
Here it is in operation. (Sped WAY up so you don’t have to watch for a full three minutes.)