Just about a year ago, last August, we welcomed special guest Lenore of Evil Mad Scientist Labs on our weekly solder sesh! While Carrie soldered up an EMSL XL741 Kit, they got to geek out about 555 timers, 741 op amps, and #plottertwitter! Lenore talks us through what piqued her interest in electronics, various pen plotting robots she's collaborated on, and how it lead to the AxiDraw pen plotter!
You can find Lenore on Twitter and Evil Mad Scientist Labs on Twitter, Instagram, and YouTube!
(3:23 – 11:12) Lenore’s Kits
Carrie: Should we do a little introduction for people who might not know what a 555 is? What is that chip anyway?
Lenore: The 555 timer is a ubiquitous chip. It's in almost everything, it's a timer; anything that has blinks, that need something to happen on a schedule, that makes tones all kinds of things. The 555 is in your washing machine, it's in your toaster, it's in your car. It gets embedded into other chips. It’s one of the most produced chips of all time. And like I said, it's just in everything. It was designed by Hans Camenzind in 1979, I think. Since then, it's just been used in so many different things.
Carrie: It was really the first way that you could make, with a single chip in minimal surrounding circuitry, a train of pulses, like a clock train or something like that. Something that could be used to keep time with microprocessors or blinking things, whatever. It was the first of its kind.
Lenore: It was one of the early ICs. They were just starting to make circuits that did a thing that you were putting together more than just gates and so on. It was really used in so many different things.
Lee: I feel like it's a really cool chip for beginners to really understand ICs. It was the first IC project that I did! First make the light blink and then you make that light theremin circuit and you're like, “Oh, I get what an IC is doing, and it's not just some computer stuff,” you know?
Lenore: Right. It's not a microcontroller where it's hidden in the code or there's software part of it. It really is electronics. You're using the circuit to create something rather than taking it out to another level of abstraction. There’re tons of kits that are built around it. There's the Drawdio Kit where you make a musical pencil and just all kinds of things.
Lenore: So, a friend of ours also brought a 555 project to the Analog Aficionados event. He brought this [Lenore holds up a 555 circuit on wooden breadboard], made by Eric Schlaepfer, @TubeTimeUS on Twitter. This is a 555 circuit on a traditional bread board, an actual wooden board - it's all of those transistors and resistors, that's all that it's built up of. He has set this down on top of our [555 timer] footstool and we were like oh we have to do something.
Carrie: That is awesome.
Lenore: So, we made the 555 Kit. You were talking about blinker circuits, and I've got an example. Here’s our 555 Kit, set up with my 9V battery here, and this is just an LED blinker circuit. It’s just a couple of resistors, a capacitor, and a power source; it's one of those things you can make something that does something with fairly few components. After we made the 555 Kit people loved it and were like, “Oh, what are you going to make next?” because we made the 555 with these cool decorative legs – the stand for it that look like IC legs. So, we wanted to keep in this form factor, the DIP [dual in-line package] eight form factor, so other popular chips that come in a DIP eight. DIP is dual in-line package, so your standard through-hole chip package.
Carrie: Yup, two rows of legs.
Lenore: The 741 [op amp chip] was another obvious one in part, because it gets used in a lot of things. It was one of the early op amps and was the first op amp to include a capacitor inside. That took up a lot of die space because capacitors take up a lot of area, so that's how it came about. You can see the capacitor on board, a little different ratio when it's a discreet component.
Carrie: I was surprised that this only had one capacitor in it. I don't know, I just assumed that there would be more.
Lenore: You would need so much more die space!
Carrie: Yeah. I mean, things are always getting smaller and they're always coming up with new materials and new ways of doing things. I wonder, are capacitors on dies a lot smaller now than they were in the 1970s, or is that just some laws of physics that you can't really get around and they still take up a lot of space?
Lenore: I think it's laws of physics and we tend to just use discrete capacitors for the most part now. if you're interested, I think that Ken Shirriff [@kenshirriff on Twitter] did a die photo and article on the 741, so you can see how much of the die the cap takes up. He also did one for the 555 which is just fun as well.
Carrie: I didn't know that people hide artwork on integrated circuit dies.
Lee: That's one of my favorite electronic secrets to have ever discovered. It's so physical and fun.
Carrie: So, dies are the substrate that your entire circuit is printed on, that are microscopic, that are inside of these, you know, black bodies that make up our ICs. So that's what we're talking about when we're talking about dies. On microscopic levels, people put little fun action figures and artwork and weird stuff on there. So, it's lurking in all of your electronics without you even knowing about it.
Lenore: Yeah. There’re some famous ones that have like a pair of scissors, there's signatures, there's all kinds of stuff. So, we call these our disintegrated circuits because they're integrated circuits that you blow up and take apart and make from discrete components. But one of the things that we realized is that it would be fun to do an intro surface mount version of them so that people could get started with surface mount soldering or just for fun. Here's the 555 version of that. One of the fun things that we did with this is we made it to scale, so you've got your DIP 8 and your SOIC.
(30:36 – 36:48) Pen Plotter and Egg Bot
Carrie: So, tell us a little bit about the pen plotter and about the EggBot, too. Those are super cool things that you guys make.
Lenore: The EggBot was our first pen plotter, it draws on spherical and egg-shaped things. That was a collaboration with Bruce Shapiro of The Art of Motion Control. He's a motion control artist and wanted to bring it out to a wider audience but didn't want to do kit production. So, we worked with him to get it manufacturable and supportable. One of the challenges with things like the pen plotters is that you have to support software and it needs to work on peoples’ computers that aren't yours.
Lenore: The EggBot works with an extension for Inkscape, the vector art program. We'd been working with Inkscape since EggBot came out in 2010, a really long time now! The next pen plotter that we made was the WaterColorBot, which was a collaboration with our friend, Seth, who wanted to take wanted to compete in a robotics competition in the art bot category. So, we helped Seth create the WaterColorBot, which was a lot of fun and such a great experience that we wanted to get it out to more people. So, we worked together to get that out. It's not currently in production; it turns out there's not a huge market for low precision watercolor robots, but it was very fun.
Lee: I feel that’s totally part of its charm! That's why I love it. I'm a huge fan of low precision robots, but I see why.
Lenore: The WaterColorBot inspired our friend, Lindsay Wilson, to create the first version of the AxiDraw. He didn't want to go into production, so we took the project over, re-designed it again for manufacturability and supportability. That came out 2016, we started making it and were absolutely inundated with orders. I had no idea that people needed pen plotters!
Carrie: What are they using them for?
Lenore: My favorite and what you will see a lot of in the right places of the internet is the algorithmic artists. So, #plottertwitter.
Carrie: I need to look at this.
Lenore: I love #plottertwitter! There's so much beauty there; there are even people using AxiDraw with watercolors. I've seen some people doing other kinds of paint things with AxiDraw, as well. Plotters are just fantastic, and my favorite is the algorithmic art community, but the most popular use for it is handwriting, like applications for marketing purposes.
Lee: I hadn't even considered that. In my head it was all #plottertwitter. That's just my art brain. I'm like, “Yeah, for sure, it's just robots drawing stuff.”
Carrie: That is so interesting to me that people are using it for that kind of marketing application. I'm curious why wouldn't you just make something using an iPad and whatever artistic software you like and then print it? What is different about the ink plotter or what kind of feel does it give rather than sort of a more traditional printing process?
Lenore: Well, if an envelope comes to you that was written with a pen versus one that is ink-jetted with a handwriting-like font. Which one are you more likely to open?
Lenore: Or you are ordering something from an online company for the first time. They want your loyalty, and they include a handwritten note in the package thanking you for your order.
Carrie: So basically, we need to stop handwriting our notes and get one of these plotters – get a robot to do it for us!
Robyn: Can they hold sparkle pens?
Carrie: Yes, can they hold sparkle pens? That is very important to us at Alpenglow Industries.
Lenore: Yes, they can. There's a discord for the Plotter community. I'll think of the name in a minute, but it has lots of discussions about pens and specifically gel pens, and more specifically glitter gel pens. Also, the color changing gel pens – all of that, yes.
Carrie: Awesome. That is rad!
Lee: I’m just about to put a UV pen in my plotter. So yeah, I'm all about this.
Lenore: Yeah. I love the stuff that people do with UV stuff or the writing on glow in the dark materials with a laser so that you have temporary artwork that fades. Those kinds of things are really cool.
(42:37 – 49:52) What’s an Op Amp?
Carrie: So, we have a question in the comments of what is an op amp?
Lenore: Op amp stands for operational amplifier. It's used for amplifying a signal or a voltage or – I don't know what. Here’s the thing, I've only used op amps a little bit, but I make a lot of them. So, I'll let you go into the technical details.
Carrie: Yeah, I would say that another reason op amps are kind of cool is that they can do more than just amplify. So yes, they can amplify signals, but what do we mean by that? Well, if you think about the volume knob on an old stereo, the volume knob is actually just a variable resistor and that is hooked up to your audio signal and also to something like this op amp. It actually makes your audio signal grow and shrink as you twist that knob. That’s what we mean when we're talking about amplifying; the amplitude of your audio signal is what correlates to volume. So, they can do a bunch of stuff like that.
Carrie: There were a lot of old analog sensors, although they weren't old when I started into electronics, and it was the way things worked. Basically, they changed resistance with respect to some sort of input. Some things change resistance when the temperature changes, some things change resistance when pressure changes. You took these little resistor bridges and what you could do is you could power them and then you can see a tiny difference in signal that was made by that resistance change. Then you would put them through this amplifier so that you would be able to look at the range that you wanted to and be able to get a lot better resolution in that range. So, instead of just being able to differentiate, like boiling and freezing, if you then amplify that signal, you could be like, “Oh, this is 75 degrees and this is 80 degrees…” that kind of thing. So, amplifiers were used a lot in instrumentation and there are specific kinds of amplifiers that are made of usually three op amps that are called instrumentation amps that are used for that kind of signal processing.
Carrie: I think pretty much all sensors are now digital. They just spit out a bunch of 1s and 0s that correlate to your temperature or your pressure or whatever, but they still have all of this stuff internally in their ICs. It's still definitely useful to understand how they work! Another cool thing that they can do, that's not amplification, is they can be used to compare two signals. So, is this signal bigger than the other one? If the answer is yes, then I output 5V. If the answer is no, then I output 0V. It was a very early way of creating something that was digital signal friendly that was only either at 0V or 5V that a little processor or computer could actually read and do something with. You know, versus having this signal that changed in infinite increments between 0V and 5V.
Carrie: I think that A to D converters – converting an analog signal that has basically infinite variation between 0V and 5V – converting that to a digital signal that a microprocessor can understand, store, and read. I think that that's still done with capacitors and op amps and it's like, “Okay, is this a signal bigger than 2.5V? Yes. Okay, then we'll see if it's bigger than 3.75V. Yes. Okay…” That's how a SAR ADC [successive-approximation register analog-to-digital converter] work, successive approximation. I forget what the R means, but that's okay. So that's an interesting use of op amps, and that's called a comparator because they're comparing to things.
Carrie: You can also use them to not necessarily amplify but offset a signal. So, if you have a signal – let's say an audio signal that's going through ground – it's varying between positive and negative voltage that you need to interface to something that needs to read a signal that's between 0V and 5V and it can't see anything below 0V. Then you can use an op amp to offset that signal, so now it's going between 0V and 5V instead of positive 2.5V and -2.5V. It's useful in a lot of signal processing things.
Lenore: One of our first set of kits that we made were for interactive LED projects and we made one that was entirely analog. It was op amps, resistors, and capacitors, and it would create a damped oscillation. So, when you got a signal from the changed photo transistor, it would trigger the oscillation which would then dampen out, but it also sent a signal to its neighbor who would get a smaller signal and would also oscillate, but at a lower amount. It was sort of a networked analog computer that would just ripple in the amount of light that it had. It was a lot of fun! Occasionally people would say things like, “Would you please make sure that the chips are programmed?” And it was like, “Well, these are just op amps.”
(51:09 – 58:29) Lenore’s Path into Electronics
Lenore: Leeborg you were going to ask something.
Lee: Oh yeah! I was going to ask you – I had no idea your background was not technical, I just make random assumptions – I was wondering, was there a project that you were involved in or saw that really made you fall in love with electronics? Something that really captivated you about it?
Lenore: Electronics specifically, that's a really good question. The first sort of electronics projects that we did were LED projects; stuff to light up our bikes when we were dressing them up for events. So that was much more about display than about electronics themselves.
Carrie: That's okay!
Lee: That totally qualifies!
Lenore: Yeah. The other super inspirational project from a different direction was seeing Bathsheba Grossman's sculptures at Maker Faire. I don't know if you're familiar with her work.
Carrie: I don't think so.
Lenore: She is a sculptor who works primarily in 3D printing, and if you'll hang on for just a second, I'll grab a piece!
Carrie: Ooh, yeah, absolutely.
Lee: It had me thinking about when I was in school, and I took this class called electronics for artists and we had to make a switch. We can make a switch out of anything conductive. I still make my students do this. I had no idea what I was going to do, and I ended up making a switch out of a pineapple. You put the head of the pineapple on, and the LED would turn on and I was like, woah electronics could be anything. I think of that as my origin moment.
Carrie: I love it, pineapple electronics. Now I want to make a circuit out of pineapples.
Lenore: So, this is one of Bathsheba’s pieces [2:07 in Highlight Video #4]. This is made out of sintered metal and it's mathematically complicated, right? It's just really beautiful, super satisfying to hold, and absolutely gorgeous. We saw her work at the very first Maker Faire back in 2006 and were just smitten. That's when we started working on the CandyFab project, a 3D printer that worked with sugar as the printing media. That got me not so much into electronics as into mechanisms. The Z stage for the original CandyFab, the vertical motion system for that, was made out of a car jack that we had turned into a servo motor to lift a large volume of sugar up and down, plus the wooden bucket that held it.
Lenore: It needed to be able to lift a lot of material very precisely. The types of mechanisms that we use for that were all fun and repurposed and interesting. We actually used pen plotters for a lot of it, because you could get the old HP pen plotters at the surplus stores for next to nothing; they have linear shafts and motion control stages that are wonderful quality. So, we did a lot of repurposing as we moved forward with the project. We started trying to recreate those types of designs and build something that was manufacturable from scratch, which is a lot harder in some ways. It's very hard to give someone instructions to make something I found at a surplus store.
Carrie: I just totally thought of an engineering use for pen plotters, which I have actually done before. Which is you can use them to plot circuit boards on copper clad substrate and etch your own circuit boards with them.
Lenore: Yep! That is something that people have done with AxiDraw. The other way that you can do that is actually with a conductive pen. You can just draw your circuit instead of etching it – people have done that with AxiDraw and EggBot as well – if you need a spherical circuit.
Lee: If you need a conductive egg.
Carrie: Was it way easier going from EggBot to pen plotter that just has two axes?
Lenore: No, because the EggBot is essentially direct drive. You have a motor that's turning the egg and you have a motor that's just turning the pen, just moving it in an arc over the egg. There's no, or very little, intermediary hardware; for the pen, there's a servo motor that just lifts and lowers.
Carrie: Is it spring loaded to keep touch with the surface of the egg?
Lenore: No, it is gravity driven. It's lifted away from the egg and then lowered to just ride along the surface of gravity and that’s true with the AxiDraw, as well. The WaterColorBot had power down, it would press the brush down because you need to be able to push the brush onto the paper. The AxiDraw and EggBot are both just gravity driven. So, no, all of the other types of motion control that we've done are more complicated because you need some kind of hardware to translate it into those positions. The AxiDraw does not have any moving motors and neither did the WaterColorBot. The WaterColorBot used an Etch-a-Sketch-style motion system with cords that hold the stages around and the AxiDraw uses a single belt that's connected to two motors. Neither of those is specifically X or Y, it's a combination of them that drives it to the correct location. So those are all much more complicated than the EggBot, which is just a direct; we have rotation, we have pen, and that's it.