Arfink Gets Random Part Two!

[arfink]

[media]http://youtu.be/s_2JJrkyeOs[/media]

 

I got a new toy today, an old Sanyo Comet II pachinko machine. I've wanted a pachinko for a long time, and this one was in fairly good condition on Craigslist. Bella loves playing with it!

It does have a few small issues. The jackpot payout lever sometimes gets stuck, resulting in no payout after hitting the tulip, although this is relatively rare. Some lubrication ought to do the trick. Also, the lights and original wiring were missing, and will need to be replaced. I'll probably use LEDs. Finally, it's still rather gross and dirty. Needs a good cleaning, and possibly some paint touchup inside the play field.

 

 

[brianthephysicist]

That's awesome, dude

[arfink]

Well, trying to get work done from home again today. It's challenging! Say a prayer for me please. :)

[arfink]

So, today's entry should probably be titled "Misadventures in Modding."

 

That's the parts on the left, Famicom game console on the right.

 

I started with a stock Famicom. You know, the old Japanese game console. I want to make it work on a US television. It's a fairly simple mod really, all you have to do it remove the existing Japanese RF modulator, put in a new video amplifier, and a little fiddler circuit with 2 resistors and a capacitor, and you can hook it right up to a US television with that familiar yellow RCA plug. Not a big deal, right? Well, apparently not, if you're me.

 

For starters, all the schematics I found people using online disagreed with each other, and some of them were just plain wrong. I eventually figured out one that should work pretty well. I tried to find the right parts in my own parts bin, and found that the parts I should have had were nowhere to be found. Hrmph. Sooo I broke down and ordered the parts, which arrived today.

 

So the first thing I needed to do was determine where on my Famicom's circuits I could find a +5 volts line. I was just gonna pop a power supply on the thing and test it out, but didn't know what kind of power supply to use. Once again, looking online I found two different websites, one of which insisted that the plug is positive on the center and negative on the outside, and another which insists the EXACT OPPOSITE, that it's positive on the outside and negative on the inside. Not helpful! Looking at the actual Famicom I could determine which one was supposed to be positive and which negative. (the positive goes on the outside, guys!)

 

So then I found a suitable looking power brick with the right sized plug in my stash, and decided to try it out. I tested it with my meter, and read -.05V DC instead of 9V DC. Huh, that's odd, I thought. Wonder if my meter is broken. Of course, meter was not broken, it can read the correct 1.5V DC from a AAA battery. So I decided to try the power supply anyway, what could go wrong? Maybe it's just a fluke. Stupid me.

 

The supposedly DC adapter was actually an AC adapter, which I would have noticed had I read the fine print on the backside. The voltage regulator in the Famicom made much protestation by being smelly and getting extremely hot, hot enough to burn me good after only a couple seconds. I guess I need a DC adapter. Sheesh! Hopefully the rest of the evening goes better. :P

Edited July 4, 2013 by arfink

[arfink]

Sigh. I did all the things I needed to do, and it's still not right. The darn thing is all wavy and totally messed up looking, and I did everything correctly too! I am a little upset, but I'll crack this nut sooner or later.

[AnneLine]

:console:   sounds like a rough day.   Ice cream?

[arfink]

Well, maybe iced tea instead. ^_^ (herbal, no worries Annie!)

 

I think I may have found my culprit though. I was just pondering the video output that I was getting, and thinking if maybe the symptoms would tell me more about what is causing the problem. The more I looked at the image, the more I was convinced that I was seeing 60hz line noise. So, first an explanation of what that is:

 

US household electrical circuits run on AC, which means the current changes polarity 60 times a second, or at 60hz. This current change is gradual, and if you graphed the change in voltage over time, it would look like a sine wave:

 

 

Now, badly designed power supplies will not filter this sine wave out of the signal. Instead it will simply use diodes to "rectify," or flatten the curve, but the noise will still largely be there. Now, this noise becomes part of the DC being fed into the console, and causes signal instability. A simple square wave suddenly looks like this:

 

 

Now, because the noise is based on the 60hz sine wave, the noise will have a sinusoidal (or sine-wave-shaped) amplitude, and so the output will literally look like it's being driven by a sine wave. That's what I was seeing. The image was getting moving bands of light and dark, which would also slide sideways a bit. It made the picture look like it's doing the wave! So I think I need a new, not so horrendously cheap, DC power supply. In other words, something nicer than this:

 

[AnneLine]

Your new toy will not use the pet door.  Somehow that just makes... sense.

 

Enjoy your tea.  I'm gonna eat your ice cream.   Told you I was a :brutebeast: !

[arfink]

I have developed a new software toolchain for doing halftones for my laser engraver. This one was made with GIMP and Inkscape together. I think it's going to look very very cool when laser engraved.

 

 

 

[AnneLine]

That does look interesting, ARFink.   Don't totally understand all the ramifications, but if it makes pretty art, and you happy, I'm happy.

[arfink]

That does look interesting, ARFink.   Don't totally understand all the ramifications, but if it makes pretty art, and you happy, I'm happy.

 

Well, this is called halftoning. It's an illusion technique. Basically it allows me to create the illusion of much more gradual shading, when in fact there are only 2 colors being used. The laser's built in halftone is nice enough, but I wanted much more control over it, with the ability to make the halftone more "coarse" to produce a more graphic effect.

[AnneLine]

Is the stripe-y effect the half tone, is it what the actual art work looks like, or is it a frunction of getting a screen shot of a computer screen?

[arfink]

Is the stripe-y effect the half tone, is it what the actual art work looks like, or is it a frunction of getting a screen shot of a computer screen?

 

The stripes are part of the design. :)

 

Let me explain it this way. The laser only has 2 firing modes when it's being controlled by the computer: on and off. You can sometimes control the color of the engraving by adjusting the power, but this cannot be done on the fly by the laser controller, it must be done before hand.

 

To simulate shades, you have to have alternating patterns of dark and light which trick the eye into seeing a particular shade. This is the basis of all forms of printing, from wood-prints to lithography to screen printing. And it is the case with the laser as well.

 

In my case, i desire to increase the size of the alternating patterns of light and dark, to produce a more "graphic" or perhaps low-fidelity effect.

[AnneLine]

That's what I thought, but I wasn't sure.  Thank you.  It isn't often we get to ask an artist about his or her work... :)

[arfink]

If you want to see another cool example of halftones, try this:

 

 

Get it up on your computer screen, and look at the big "grain" in it. Looks recognizable, right? But of course the colors seem jumbled. This is from a newspaper, where they only have cyan, magenta, yellow, and black ink in their printing machines. So they make spots of it close together, and the closeness of those spots will change the perceived color. To see what I mean, walk away from your computer screen a ways and look at it again. Once you are far enough away, the colors will appear smooth and you will not see the grain. It's a clever way of tricking the eye into seeing shading where they isn't actually any.

Edited July 5, 2013 by arfink