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Drawing with charcoal

By John, 22 September, 2011

People draw with charcoal sticks, right? Charcoal sticks are expensive. Why can't I pick up some charcoal from a fire and draw with it?

A child's hands drawing with charcoal

Well, I can. And it works.... okay. The problem is it's hard to get a really deep black. Straight charcoal doesn't dig in to the paper, it sits on top of the paper. If I draw over a line I've already made, I'm pushing the other charcoal out of the way. There gets to be a bunch of it on the surface of the paper. And, of course, it's really easy to smear.

This picture shows how easy it is to smear charcoal on paper.

I guess the next step is to crush it and mix it with some kind of binder. If I use wax I'll get crayons, if I use clay I'll get conte crayons (broadly speaking).

At any rate, the kids had fun, and clean up was super easy because the dust didn't stick to anything and we tried to keep them from grinding it into the carpet.

A child's hands drawing with charcoal

Member for

13 years 2 months

noahgrey

12 years 11 months ago

I've done a lot of drawing with charcoal (store-bought, not "real," so not sure of the difference there), and in my experience it greatly depends on the kind of paper you use. Ordinary printer-type paper is too slick, but thick textured drawing paper will soak up more of the charcoal and give you much more leverage to play with its wide range of shadings. (And if you really want to get into it, it's also worthwhile to get some fixative, both so that you can do multiple coats and so that you can preserve what you want to keep -- without it charcoal drawings will smear and fade at the slightest excuse, especially on regular paper.)

Member for

13 years 2 months

John

12 years 11 months ago

Hmmmmmm... so maybe my charcoal is just charcoal then?

I made some charcoal sticks of my own while on vacation. I put some maple sticks in tinfoil and threw them in a fire. The tinfoil was too thin and several packets got breached and flamed up before I figured out what was going on. I fished the rest out of the fire and clipped off the parts that were on fire and burned myself and... yeah. Then my kids got ahold of the remaining sticks and now I have stick pieces.

Next time I'll make it in the grill. Then a log won't land on it.

Anonymous (not verified)

12 years 10 months ago

When making your own charcoal stick you shouldn't open whatever they are sealed in until they've cooled off.

Stella Amp build update

By John, 24 August, 2011

I've been building one of my Stella Amps into a cigar box. I've been taking pictures the whole time, and some day I'll collect them all to one post. But for now I'll post what i just finished up.

Here in this pic you can see the knobs I just put on, and the new hinges. The old hinges were push-in cheap shiny brass and they fell apart pretty quick. (My kids might have had something to do with that.)

New (old) hinges on my cigar box amp.

The new hinges came off an old jewelry box my wife didn't care about any more. I don't know what she did with her jewelry box, but I got the hinges. I had to be real careful to avoid over-tightening the screws with that soft plywood.

The inside of the cigar box amp.

This is what it looks like on the inside of the cigar box. I don't have anything mounted yet (need to get the right kind of screws). I took off all of the tape holding everything to the sides so you can see the internals. Here you see the Stella amp, and in the back, you can see the Tillman preamp I put in. The speaker is a 50W Boss car audio speaker.

Next step is mounting everything securely, including a new 4xAA battery holder. I also need to make a hole for the input jack and some labels for the controls.

Member for

13 years 3 months

John

12 years 11 months ago

It sounds fabulous. I have some video of it but I haven't put together the footage and edited it yet. One thing I really like about it is using it for an ipod amplifier. Yeah, it's not stereo, but I love playing old mono jazz recordings through it. And podcasts are great, because the cigar box gives it a little bit of an old time radio feel.

Another thing that's great about it is practicing the bass. Yes, it's very quiet but that's what's so great, I can take it all over the house when the kids are asleep and never worry about waking them up.

Chris (not verified)

12 years 11 months ago

I built one of your kits and it's fantastic. I did happen to destroy my c11 capacitor. You says its ceramic. Would that be multilayered ceramic? You got a digikey or could suggest something I could sub it with? Thanks!

Ps. I soldered my remaining resistor into rpd2. There wasnt anything for it on the build page. Is that right?

Member for

13 years 3 months

John

12 years 11 months ago

I'm glad to hear that you like it! Let me know if you have any build photos or if you make a video of it, I'd love to see it!

The digikey part number for C11 is 445-2857-ND. Any 1 uf, non-electrolytic capacitor should work just fine.

Rpd2 isn't going to hurt anything. It is an optional part that you only need if you are using the amp as a stomp box. It is there to help remove pops when you stomp on your stompbox. But if you are using the Stella as an amplifier and powering a speaker, the resistance of Rpd2 is so high it's not going to affect the amp output.

pcdjviro (not verified)

12 years 9 months ago

Hello I bought your Stella Amp when it was featured on Make's Site. I'm powering this unit with a switch mode power supply at 11 volts. Can you suggest a speaker for this current setup? I dont want to waste any cash on something that wont sound well. I have read about car speakers being installed. Is there anything special involved in the setup using that kind of speaker?

Member for

13 years 3 months

John

12 years 9 months ago

Well, I don't know how big of an enclosure you'd like to put it in. Any speaker 4 inches or larger that handles 3 watts or more will probably be great. Either 4 or 8 ohms is fine.

For a cigar box amp (or even a little larger) I like these: http://www.amazon.com/BRS40-Replacement-Individually-Packaged-Clamshell…

The 3.5 inch in that line of car speakers is too small and I don't really like it as a general purpose amp. It doesn't have enough bass for me, although maybe if I had it in a more rigid, air tight enclosure it would work better.

One thing to watch out for is make sure you are getting a full range driver. I got a nice 10 inch speaker but I can't get any highs out of it. (I might pair that 10 inch with the 3.5 inch boss one!)

Eric (not verified)

10 years 9 months ago

I have a box that's going to be a bit larger... what is your standard size of speaker you like to use? I mean, if not constrained by size limits? Any particular one you'd recommend?

Sentences to ponder:

By John, 17 August, 2011

The National Security Agency wrote the Security Enhanced Linux extensions which are now a fundamental part of Red Hat and a few other distributions. The work the NSA did made it so secure that Linux is now the most secure operating system certified by the Russian government.

That is from Red Hat's CEO at LinuxCon. The rest of the article is Linux hagiography if that's your thing.

Anonymous (not verified)

13 years 1 month ago

Showing yet again the usability and security are inversely proportionate.

Let's make mistakes: experiments

By John, 9 August, 2011

Here are some recent experiments I've tried:

Making tapioca pudding from scratch, using real vanilla beans: partial success. I never made pudding from scratch before. The pudding recipe (on the bag of tapioca balls) was extremely finicky, it took hours, and never did set. On the other hand, the vanilla bean (I used a half a bean) was a huge hit, and overall it tasted amazing.

Adding vanilla extract to lime flavored seltzer water: success. The lime flavoring was pretty bad, especially when compared to actual lime juice (which is what I had been using to flavor plain seltzer water for the past few weeks or so.) I added the vanilla extract and it's actually pretty good.

Adding Worcestershire sauce to lime flavored seltzer water: failure. Well, how are you going to know if you don't try? (The lime interacted with the Worcester and it was really bad.)

Adding tabasco sauce to lime flavored seltzer water: more data needed. I didn't like the vinegary taste but I loved the spicyness exploding with the carbonation. Maybe straight cayenne powder mixed in would work?

Steaming bitter lettuce greens: failure. We had some lettuce in our garden that had turned far too bitter from the heat. I thought I'd steam it to see if I could get the bitterness to go away. It didn't.

Steaming cucumbers with dill: success. This one was a surprise to me. Steamed cucumbers are a bit firmer than zucchini or yellow squash but are nice and mild and have a slight flavor that is only vaguely reminiscent of cucumber. It actually tastes... well, like a completely new vegetable. Next time I will season them a little more heavily.

Amy (not verified)

13 years 1 month ago

If you're wanting to experiment more with vanilla beans, search for them on ebay. There's a reputable seller on ebay whose prices are delightfully low. I've sent a few packages of vanilla beans to my friends.

For the bitter greens, two thoughts: some acid flavors might've helped, and you might've needed to braise the greens for a long time. It's how endives and collards are made palatable.

Member for

13 years 3 months

John

13 years 1 month ago

Amy, thanks for the tip. What I actually did was wash them, lightly shake them off, put them in tinfoil with some oil and threw it on a grill.

And you don't have to cook collard greens that long if you cook them in bacon grease. :)

The Sinister Minister

By John, 6 August, 2011

I want to show you something amazing. This video is in two parts. Here is the first one. It's a great performance of The Sinister Minister by Bela Fleck and the Flecktones. Note especially the flute and banjo parts, they're very good.

But that video is just the warm up. The real amazing part of this song is Victor Wooten's bass solo, which lasts for most of the second video. And I want to call a bit of attention to something that happens early on in the solo:

Victor breaks a string.

Well, people break strings all the time on stage, right? But I watched this video about 10 or 15 times without noticing it. Wooten's performance is so good, it's hard to imagine that he is actually missing a string for most of his solo. Even after someone pointed it out to me, I still missed the spot where he broke the string, several times.

Here is a handy timeline. I bolded the important bits.

1:29 We can clearly see that he has all four strings.

2:24 This is some amazing slap bass.

2:39 I love the chord strum here!

2:47 He breaks the string and pauses. But the pause feels dramatic. It doesn't feel like there's anything wrong, it feels like he meant to stop there for emphasis.

2:49 He breaks into a simpler low key groove to give himself time to think.

2:56 Fast hand flick to move the string out of the way.

3:05 He's keeping it simple but varying it it up a bit. Clearly still thinking about what to do next. Remember this solo is a big deal, it's supposed to end on a super intense note before the rest of the band all comes back in. This is the last song in the set, he can't just trail off and end the song.

3:12 Back to the groove. Still thinking. Not only does he have to improvise his way through the rest of the solo, he has to play a quite distinctive main bass line when his solo is done... while missing the G string. More on this later.

3:21 Still thinking... Let's see how gets out of this.

3:50 I love how you can see the string just hanging there.

4:48 He tries to yank the string off but can't

5:05 String flying in the breeze

5:19 Ever so slightly reminiscent of "Play That Funky Music"

5:30 So amazing.

6:00 What the hell is going on here.

6:20 This rhythm stuff is amazing, he's fretting the notes on the neck to get the right chords when he bangs the strings.

6:30 Notice that he starts slapping all the strings with no fretting. It's great but kind of cacophonous and musically dissonant. There is a pause as Futureman steps in to cover for what happens next. Hard to tell with the camera angle but Victor probably gave some look or signal that brought him over.

6:37 Finally gets the string off and hands it to a fan in front

6:41 This is critical! We see him retuning his bass! In particular we see him tuning the E string. He's probably tuning it up a whole step to F#. This would give him an inverted D chord if he slaps all the strings at once without fretting them. Remember when he's done with the solo he needs to get back to the regular sinister minister bass line... but he doesn't need the E string for that. He does need the G string which he broke, but when he finishes his solo and starts up the main bass line you can see he improvises by playing way higher on the neck to get the notes he needs on the D string. Of course he then has to ether be extremely fast to move up and down the neck to get the notes he needs on the A string or he has to transpose the rest of the bass line to his re-tuned E and A string. I think he does a little of both but I get ahead of myself. (There's also a possibility he re-tunes more than one string here. That invalidates some of what I said above but makes any transposing he has to do later more impressive.)

7:05 We see the results of retuning here as he slaps all the strings and it sounds so good compared to the cacophony earlier. Note that the rest of the solo is rhythmic, not melodic.

8:52 Back to the main groove.

And that, my friends, is a professional at work.

Putting all of this together, I was strongly reminded of David Foster Wallace's essay on Roger Federer, specifically Federer's ability to see several steps ahead in the game and maneuver his opponents without them realizing it:

Federer is able to see, or create, gaps and angles for winners that no one else can envision, and television’s perspective is perfect for viewing and reviewing these Federer Moments. What’s harder to appreciate on TV is that these spectacular-looking angles and winners are not coming from nowhere — they’re often set up several shots ahead, and depend as much on Federer’s manipulation of opponents’ positions as they do on the pace or placement of the coup de grâce.

If you want an MP3 of this performance, it's freely available on archive.org. The original song is also not to be missed; it was released in 1990 on their self titled album Bela Fleck and the Flecktones.

Why are gas stations clustered together?

By John, 28 July, 2011

Presh Talwalkar over at Mind Your Decisions has noticed that gas stations tend to cluster together in urban areas. It seems like every time you find a gas station, you find another one across the street. Anecdotal evidence suggests this is true.

Presh, being a game theory guy, sought to explain this in terms of game theory. The basic idea is that gas stations are mostly interchangeable and that if people are going to randomly choose your product or the other person's, you might as well locate yourself right in the middle of the area so that the most customers come to your gas station and the other person's gas station. If you get to close to an "edge" then your competitor can move into the space you are "ceding" and gain all of those extra customers.

No doubt there is something to that. I am reminded of voronoi diagrams of McDonald's locations.

He does say in the post that it's a simple model. "There are clearly many factors at play. It’s an optimization involving demand factors, real estate, estimates of population growth, and supply considerations—like the ease of refueling a station. The answer is complex, and any explanation I offer will have its problems."

True, but it doesn't mean we can't take a stab at it. Here are a few other hypotheses:

1. Traffic levels, lane configurations and even one way streets may make it impossible for me to pick which gas station to go to, even if I really want to. If the gas stations are "across the street" on the map it may be nearly impossible in practice to substitute one for the other without taking a long detour.

2. Certain types of businesses tend to cluster together because the cost of leasing the space and operating the businesses are similar. Kinkos is more likely to be in the same strip mall as Batteries Plus because they have similar fixed cost structures and size requirements. Perhaps the location of gas stations is similarly affected.

3. What about zoning regulations and local planning commissions?!

4. Gas buddy relies on a system of volunteers to report gas prices. It's possible that this is not a fully systematic, comprehensive data set and that smaller neighborhood gas stations are getting underrepresented.

5. Maybe gas stations really are randomly distributed, but they are randomly distributed on the busiest roads. This causes them to "bunch up" together more than they would otherwise, because they're all seeking a spot on the roads with the most traffic. If traffic levels were not a factor in business success, perhaps they would spread out more in suburban areas instead of clustering together.

#1 is the first thing I thought of, and #3 is probably the most likely.

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Arbitrary colors for the Adafruit 1.8" TFT display

By John, 2 July, 2011

I love Adafruit. I especially love their little 1.8 inch TFT screen that you can hook up directly to an Arduino. It comes with a library, but one thing the library is missing is a method for generating arbitrary colors. The colors are in an odd packed 16 bit binary format, with 5 bits for red, 6 bits for green, and 5 bits for blue. They give you a few color constants to start out with, but I wanted arbitrary colors. So I re-familiarized myself with C's bit operators, wrote some code, and now you don't have to.

The first function assumes you're passing a value from 0 to 255. The second function lets you specify the mapping, so if you wanted to create a color based on values read from the analog pins, you could do that by specifying 0 and 1023 as the minimum and maximum values.

Sorry for the lack of formatting, I can't get the formatting to look right. It should cut and paste just fine.

uint16_t makeColor(int r, int g, int b)
{
return makeColor(r, g, b, 0, 255);
}

uint16_t makeColor(int r, int g, int b, int minimum, int maximum)
{
int red = map(r, minimum, maximum, 0, 32);
int green = map(g, minimum, maximum, 0, 64);
int blue = map(b, minimum, maximum, 0, 32);

uint16_t color = 0;

color = color | red;
color = color << 6;
color = color | green;
color = color << 5;
color = color | blue;

return color;
}

Popsicle recipes

By John, 25 June, 2011

We just got some popsicle molds for making your own popsicles at home. It's amazing, I've had two popsicles a day since we got them. Here's what we've made so far, all of them have been excellent:

Orange creamsicles: equal parts of: Orange juice concentrate, milk, and vanilla yogurt (these were amazing)
Blueberries and vanilla yogurt (SUPER yummy)
Orange juice
Lemon creamsicles: lemonade concentrate, water, milk, and half and half -- keep adding little bits of everything until it tastes good. Yes the lemonade curdles the milk but you're not drinking it, you're freezing it so who cares?

I made one with part orange juice part cherry juice as a test (we ran out of orange juice) but my daughter nabbed that one when I was at work.

I just put in some straight lemonade popsicles (going for lemon ice) and a brand new idea: spicy lemon creamsicle. Spicy Lemon Creamsicle: Chop a small Morita pepper. Cover with water for about 5 minutes, enough to start softening it. Add lemonade concentrate, half and half, and milk.

I have no idea if this is too much hot pepper or not. I guess I'll find out tomorrow morning!

UPDATE: WAY too much hot pepper.

Geof (not verified)

13 years 3 months ago

When you tweeted about the disaster this could be, I was wondering what the awful would be. I should have guessed pepper.

What I've been watching on Youtube

By John, 25 June, 2011

Richard Feynman on Confusion:

Hail to the King (stick with it, it gets ridiculous after about halfway through):

Suspicious Minds (I'm trying to figure this song out on harmonica):

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