I decided to make a new page for my misc. stuff I've been working on that isn't a big enough build to justify whole page for itself. I hope you enjoy!
Shortcuts:
NES Repair
Radio Revisited
Capacitive Touch Lamp
Power Supply Repair
DFP to DVI-D Monitor conversion
Radio and Preamps
Han Solo USB Hub
So I got this NES at a thrift store a while back, which was an exciting find I must say. It is an original 1985 run and it worked very well for quite a while.
Recently, it started having trouble reading the cartridges, not terribly surprising. (Warning educational rambling ahead) The NES is notorious for having trouble reading cartridges, but most of the time people would blow on the cartridge to get the dust off and it would work. The problem with this is that, on the NES, it used copper for the contacts on both the cartridge and the system. When you blow on a cartridge though, moisture from your breath causes the copper to tarnish, and in some cases corrode altogether. This moisture also transfers to the 'teeth' on the system causing problems reading cartridges...
The nice thing is, most of the time the 'teeth' can be cleaned, rather than replaced. That's not to say they don't need to be replaced sometimes, but you never know until you dive inside. So here we go!
When you first get the top off, you'll be greeted by a large metal shield that has to come off. I've noticed that Nintendo is quite fond of these. Every system I've torn down from them has one of these big beefy metal plates around the boards. I assume this is to reduce the EMI emissions, but that's just my two cents...
Anyway, here's what we're looking at with the shield out of the way:
I stuck a cartridge in so you can kinda get a feel for what we're looking at here.
These are the 'teeth' I keep going on about. I didn't really take a close up picture, but these are pretty big full size anyway.
The cleaning process is relatively simple. You take a 'cotton swab' and some 'blue ammonia based window cleaner' (lol copyrights) and just give them a good scrubbing. Once it's all dried up you're good to go.
Here's mine ready for it's test run:
I left the top off just in case I needed to re-scrub or have to replace the contacts later.
Here we go, all better running the classic Chip 'n Dale Rescue Rangers game :)
That's all for now! If i decide to end up replacing the contacts later on, I'll move this to it's own page and go over that in detail as well.
I had to repair my old radio this week, because the tuning dial quit moving. This is the same problem the radio had when I picked it up, so I knew how to take care of it. I also figured it was a good opportunity to show off the inside. So here you go! This is a shot of the bottom of the tuner/amplifier section;
I love some classic point-to-point wiring :)
This is the same assembly from the top side:
Here's the tuner assembly repaired again:
This was a super easy fix this time. The rope had simply stretched out, so it was just a matter of snugging it back up. It works very well now. In fact, it's better than when I did it the first time!
And what post about a tube radio would be complete without a glowing tube pic?
I never get over how beautiful these things are :)
That's it for this one, thanks for reading!
Capacitive Touch Lamp
So one evening, Caytee was trying to get this old lamp of mine to turn on, but due to its "unique" (*terrible) switch placement at the rear base of the lamp, it was rather difficult. I sympathized with her plight, as I too have struggled with the demon-lamp. I have been playing around with capacitive touch circuits for some other builds I have in the works, and I thought "Hey I can fix this!" So after some tinkering, frustration with a particularly stubborn Atmega8A, a few bucks for a relay, and some clever coding, I have a touch lamp.
Here is a shot of the board wired up inside the lamp. I used an old cell phone charger and a USB cable to give 5V power to the chip.
I simply too the common and hot wires from the wall cable, ran them to the block, then back where they went. This way, if the lamp is plugged in, the circuit is on.
I also broke the connection on the common side to go to the relay. This lamp is wired to be a 3-way lamp, so in breaking the original circuit there, I am still able to set the lamp at any of the three levels and still toggle it on and off by touching it.
Here's kind-of an exploded view of the wiring, before I stuffed it all back inside.
Here is the lamp hooked up to the computer for some fine tuning of the code. I think this kind of puts it in perspective just how big this lamp is... and you are supposed to reach around behind it and try to fine the 3/8" rotary switch to operate it? Well it was free so I can't complain too much.
To get the capacitive reading from the lamp, I just used an alligator clip and clamped it to the base.
It has taken a little fine tuning in the code to get it to respond as you would expect. This is because, I learned, large metal cylinders have a fair amount of capacitance inherently, so I had to desensitize it quite a bit from my original code. The drawback in doing this means you can't operate it wearing shoes, or with your feet off the ground. Also, if you hold your finger on the lamp, you have a slow strobe light :)
I made you guys a video of it in action :)
I have started a github account, so once I figure out what I'm doing on there, Ill post my code to this, and my other arduino based projects.
I broke the connectors off of this universal power supply, so I decided to repair it.
I took the old wiring and pin holders off and figured out where to wire to.
Then chopped the cable off of an old soldering iron from my junk bin and soldered it on.
I also wrapped the cable through the holes the pins were in to create a cable relief, so if it gets yanked or anything it will be ok.
The cable and board back in place:
It works like a charm!
DFP to DVI-D Monitor conversion
So I was given this monitor to play with, because the previous owners didn't have the cables or powers supply to go with it. So I picked it up to use on my iMac monitor conversion, but more on that later.
My biggest problem (initially) with this monitor is that it uses an obsolete video cable that, until I found this, I hadn't heard of before: DFP. DFP is the precursor to the DVI standard I'm used to and, luckily, they use the same signals and video standards. This means I can simply use an adapter to go between them.
After seeing the average prices of these adapters (around $15-20) I decided to just change the connector on the monitor myself. After all, I do have an old, demolished DVI video card sitting on my desk with a good connector.
Here is the monitor torn down and a view of the board I'm changing. This is the DFP connector I was referring to:
I looked up the pinouts for both connectors at and mapped out this nifty reference sheet:
I got the pinouts at pinouts.ru. It has become one of my favorite places on the internet in the past few months. They have pinouts for almost everything I've needed them for, but I digress...
Anyway, using this reference sheet, I was able to use a ton of jumper wires and get all the signals to the right pins. It's a little messier than I would like, but it should work.
I say should, because, as of right now, I am unable to test this. I don't have a power supply that will put out the voltage that I need. It takes a 24v dc at 1.1A...
I was able to get the monitor to boot up by connecting it to -12 and +12. However, when I plugged in my bench 'Pi to it, it shut off. I was worried initially, that using the negative voltage would have some negative effect on the signal device, but I couldn't figure out what it would be.
It seems I was correct, in that I no longer have HDMI capabilities on my bench 'Pi and it has started overheating profusely. So I am putting this monitor on the back burner until I find a properly rated power supply for it.
I have managed to salvage my 'Pi for the most part. I am still able to run it with composite video or headless, though only with some serious cooling involved...
Without this fan in place, the pi heats up very rapidly and hits it's thermal shutdown point (85ºC) in about a minute. I've attempted to monitor it heating up and it got to about 81º C before it kicks me out of SSH to shutdown. With the fan in place it runs happily for hours on end at about 60ºC even overclocked to 950 mhz. It's not practical power-wise, but it works for now. I will probably stuff this inside an enclosure to use for my BabyPi setup and hook a small fan into it there, because it runs headless anyway.
However, for now. I absolutely need a replacement bench 'Pi and a few backups.
If you feel inclined to help me purchase one, I do accept donations via PayPal and it would be greatly appreciated.
This project came from necessity, more so than whimsy, as most of mine do. My older amplifier died a week or two ago, leaving me without a record player. I know it's cliche, but I really do like the sound of vinyl better than digital formats.
(warning big words ahead)
A little background info for those who don't have experience with turntables or records: the output signal from a record player is much lower than the level from modern devices and has a very specific frequency bias to maximize the sound quality, given the physical restraints of the technology at the time. To compensate for this, older stereos had a special "phono" input that boosted the signal and equalized the signal. So to hook a record player to a modern system, you need a device to compensate for these things.
Enter the Pre-Amp! There are several devices on the market available to do exactly what I need, but why buy what you can build, especially when you love to build as much as I do :) The other problem I ran into when looking at pre-built models, is that they do amplify the signal, but few are phono specific and fewer still that conform to the RIAA format for equalizing the sound. It took me a little bit of digging to find a kit to build one that had a price tag I could justify. (I found several amazing schematics for analogue tube preamps, but they would cost upwards of $100 in parts alone) Eventually, I stumbled across this schematic:
I saw they offered it in a kit and PCB, but it was more than I wanted to spend, so I shot in an order to my good friends at Newark.com (no I'm not getting paid to mention them, they're just awesome) and figured I'd just wing it.
The end result? I ended up with a tiny little board perfectly laid out, an added power switch, and on board pink LED to show when it was powered on, and battery hookups. What I didn't have was a case though... I went to a few shops looking for something pretty to put it into and found this ancient (1958) Zenith radio at an Antique store. I bought it with the intention of gutting it to put the preamp in. It said the clock part worked, but the radio was broken, so I wasn't worried about hurting it.
The Radio:
Well when I was disassembling the radio, I got to looking at the circuitry and it looked simply beautiful. A little dirty sure, but beautiful nonetheless. Anyway, I got the main assembly out of the case and noticed that the tuning mechanism was broken. This little guy just had a broken piece of string :) I thought to myself "I bet I can fix that" and 10 mins and a foot of necklace rope later I had the tuner moving it's full range of motion. I simply couldn't bring myself to just gut it anymore, so I put it back together and plugged it in. I switched it on and as soon as those beautiful tubes started glowing, I hear mariachi music coming out of it lol I ran the tuner through it's paces and it works like a charm! I currently have it set on an oldies station. It seemed fitting for the old fella (that and it's either that, talk radio, or something in Spanish I can't quite translate; not a great selection on AM radio these days)
That left me with a bit of a dilemma. What would I put it in now? Should I just stick it in the same housing? Should I go buy something else to put it into? No, I decided, it needs to go into an Altoids tin... It wasn't really even hard to do; the board I made was certainly small enough. I drilled some holes for the switch and RCA jacks, a little hot glue and Boom! Done!
Here's the finished preamp:
Powered up to show the LED
It runs off 2x 9v batteries for now. I'm working on a power supply for it, but I still have some troubleshooting to do before it's ready to use. It works exceedingly well and, in fact, sounds better than the high dollar amp it replaced :)
Sorry I didn't include as many pictures as usual, but I hope you still had a good read. Let me know if this is too much/too little technical detail and I'll adjust my future articles to suit.
Until next time!
-Baka
In case some of you may not have noticed, I am a huge Star Wars fan, so many of my projects tend to reflect that. That said, I present to you my Han Solo (frozen in carbonite) USB hub. I was at Burke Street Comics the other day and Caytee spotted this Han Solo toy and asked if it was a USB Hub. I responded simply "Not yet" with a sly grin. and here we are!
I had this old rock band usb 2.0 hub laying around that I picked up at Goodwill, but hadn't found a home for yet, so it is the obvious choice for this build.
The toy and hub before starting:
All wired up:
Nice long 'tail' for the cable
The installed ports from the side:
All in all it was a pretty quick build. I still have some bugs to work out in the wiring (there is a short somewhere but I haven't had time to track it down yet) but this is pretty much all I'm going to post on this one for now. I may add a nice back plate or some LED's later on, and if I do I'll make sure to post them here :)
That's all for now! Enjoy!
No comments:
Post a Comment