Metric Clock - Parts

These are the parts I have so far: display buttons from and old circuit board, a VFD 20 character 2 line from a cash register and a USB ToolStick. I also came up with a formula to convert military time to metric time.
Metric Time=(60x(H-1)+M)/144.
The display runs on 12 volts and the toolstick runs on 5 volts and I don't know what i'll use for a power supply for it yet.. The toolstick is really nice because they cost about ten bucks and the programming adapter is about $7. I have the f330 model but I would suggest getting one with an external crystal since the one in the f330 has an accuracy of 2 percent, so I'll have to add a crystal myself.
I would like to be able to mount the clock on a wall, but right now the VFD is about 2 inches thick. The display and the electronics are on two separate boards and connect together with 10 pins. I'm going to de-solder them all and put the controller board below the display so it's thinner and the electronics are visible.

Time for annother project

My Mom had noted that I seem to have and interest in designing and making digital clocks just like my Dad did. He built several clocks that we still use and has several skeletons of ones that were never finished. The ones that did get finished are really cool. All of the ones that work use alphanumeric LED dot displays. The one in his bedroom has scrolls the numbers like an old pinball machine when they change, dims automatically when it gets dark, Displays the date, Adjusts for leap-years, and it also used to adjust to DST (Until some weirdos changed it.) As if that isn't enough, it automatically turns on the electric blanket at a certain time, but only if it's below a certain temperature.
The one in our family room has 8 display segments instead of the 4 in the bedroom. It also scrolls the date every 10 seconds like the other one, but it doesn't have any buttons. There is a phone cable coming out the back from which it gets the time and power from the master clock in the bedroom. The clock that used to sit in the basement was like the one in the family room except it would scroll announcements like "Merry Christmas!" on Christmas day or "Don't Be A Fool!" on April 1. *sigh* I had better make my clock really cool if it's going to compete with the others.
At first I thought that I would use some of the VFD displays I found and make a "Frankenclock" which would display the time in binary, ternary, hex, Florence time, octal, Swatch beats, decimal, metric, Base64 or any other crazy system I cam across. This "Frankenclock" would be insanely geeky but also insanely hard to program. The amount of clocks/timers needed would probably be beyond the specs of most microprocessors. I could see I needed something a bit simpler.
Through my studies in Chemistry and Physics I have developed a dislike for the English measurement system. The main problem I have with it is that the units make no sense. There seems to be no rhyme or reason to the system. Us Americans are used to the craziness but what would think if someone said, "My car goes 78 leagues to the hogshead"? You'd probably say, "You're cracked!" and rightly so. Two time systems have caught my attention as being the best clock to build; Metric and Hex time. Metric is simple because you could do it with just counter chips as the time is written something like this: 27388.4589 where the 27388 is the days since 0AD or some other date, 4 is the the hour (out of 10) and and 589 would be 58.9 metric seconds. There are 10 hours in a day, 100 minutes in an hour and 100 seconds in a minute. Very intuitive.
With Hex time, there are 16 hours in a day because the hex system goes 123456789abcdef. I'm not really sure how the minutes and seconds work. The Hex system is more complicated and requires learning a whole new number system. Definitely geekier than the metric clock, but since my expertise in logic, counters, programming and hexadecimal are quite limited at the moment, I will be building a metric clock. I do plan to make a hex clock next though.

Hi-Fi Obsession - Pt. 5 - Mistakes

Yesterday, I moved my amp system back to my workbench so I could use it while sorting through the 6 boxes of junk circuits we have lying around. I had put a Molex connector on the cord coming out of the amp so I couldn't plug the thing in backwards. Well, you can probably see where this is going... Anyways, I had to re-connect the loose wires on the connector to the banana plugs on the power supply. I looked back inside the amp at the power switch. I hooked up the wires accordingly. I should have double checked.
All electronic devices have magic smoke inside them. Let this smoke out and the device will never work again. I let the smoke out. I hooked up the power supply backwards, turned the amp on, heard a pop and felt my heart sink as the smoke rose. The amp had a thick fog inside it which was coming out through little vents inside the case. Man, that stuff smells bad! I got out the screwdriver and started to take apart the case. After I took the whole thing apart, I had to locate the burnt out part inside the mess of wires. I found a blown transistor on each board. It was transistor #5 on each of the boards, a BC547. After taking them off, I had to find a suitable replacement for them. Thankfully, my Dad has accumulated a ton of little parts and has a fair amount of them sorted in little drawers. Since I didn't know anything about how to find an equivalent transistor to the ones I blew, I had to ask Dad. He did a bit of Googling, went to the parts drawers and pulled out a bag of 2n2222 transistors. I replaced the blown ones with the new ones and went to test it. I got music but lots of heat from the driver transistors. After we checked the other transistors for shorts, Dad consulted the schematic and concluded that the power supply was being crowbarred.
Crowbarring is where the two driver transistors in an AB amplifier turn on at the same time which shorts the negative and positive rails of the power supply together. since the rails are shorted, lots of current can flow through the driver transistors which makes a lot of heat. Concluding that that 2N2222 must have been a bad choice for a replacement, Dad went back to the computer to look at the data sheets. After about a minute, he called me over and said, "Josh, what do you notice about the packages on these two transistors?" I looked at the data sheets and saw that the collector and emitter pins on the 2N2222 were in the opposite positions as the ones on the BC547! Oops! once I replaced the two transistors with new ones (in case they got damaged from being put in backwards) and remembered to stick the in the right way, the amp worked perfectly again.
While I had the whole thing apart, I added a blue LED just for fun.

Hi-Fi Obsession - Pt. 4 - Sound Quality

Wow! I've never heard anything like it before. Those Bang & Olufsen Speakers are really good! There was no noise, no distortion and I heard little things in the song that I hadn't heard before. The best way to describe it would be crystal clear. I'm no professional audio reviewer person so I won't be able to describe all the little nuances of the sound, but who cares!
On New Year's Eve, we set the whole thing up by the fireplace and watched National Treasure and The Incredibles. It was like being in a theater (except for the 17 inch laptop screen). Explosions are especially cool sounding because I had the woofer volume turned all the way up. There are a lot of explosions and loud thuds in The Incredibles which was fun to listen to. It also sounds really good when Mr. Incredible hops in his sports car and zooms off.

Hi-Fi Obsession - Pt. 3 - Trial By Fire

Now it's time to see if it works. I set up the speakers, sub and the power supply on my workbench and plugged in My Zen. I selected one of my favorite songs, Missing Pages by Seventh Day Slumber, cranked up the volume on my Zen and hit the play button. I had the volume knob on the amp turned all the way down and I started to turn it up. I heard music. I cranked the knob up farther. Man, this thing can get loud even when its running on 24 volts instead of the 35 it's supposed to get! I tested both input jacks, the woofer volume and the woofer cutoff, all of which worked perfectly.

Hi-Fi Obsession - Pt. 2 - Creation

So, I got these kits for Christmas and I immediately started to build them. I finished all three of them on Christmas day. The picture on the left shows what the boars look like when all the parts are on. I didn't attach the driver transistors because I had was using the heatsinks to figure out how to build the case. I wanted something compact and cool looking that I could make with parts that I already had. The best solution seemed to be to use the heatsinks as part of the case. This would make for a really small and cool looking case.
To the right is a picture of the half assembled case. I got the most of the parts that you see from Radio Shack, except for the switches. The heatsinks are just as long as the PCBs so the fit is perfect. I put the Stereo amps on the bottom, side by side and the woofer amp I stood straight up on the right side with the cutoff adjust knob sticking out the back right corner. I could see right away that there was going to be lots of wires. I won't go into detail on how to wire the whole thing up because it's fairly simple and you can probably figure it out for yourself without much difficulty. Anyways, with as many wires as are in the thing, it would take forever anyways.
One thing that My Dad keeps reminding me to do (with good reason) is to test everything before you put it together. When I hooked up the sub amp, it didn't seem to work. Dad and I got out the voltmeter and started poking all over but everything seemed to work right. Then, Dad was playing with the current knobs on the power supply and it started working. It turns out that we didn't let the amp get enough current to run right, but when it got more, it took off and worked perfectly. The other two Amp Circuits worked the first time too.
I went to Lowe's and got some screws to hold the PCBs and the front panel on. I also found some screw in the basement that went into the little channels in the heatsinks perfectly (visible in the picture.) It was really hard to get the whole thing together. I had to reach inside with my big hands and hold the nuts while I tightened the screws. I put the left heatsink in last because that was the only good spot to reach in.
(When I find a picture of the finished product, I'll post it.)

Hi-Fi Obsession - Pt. 1 - Research

After setting my sights on a Hi-Fi system as my next project, I went scrounging for parts. I found a brand new Jensen XS225 10 inch woofer in the basement. It says 225 watts max and 75 watts RMS on the box. On the woofer itself, it says 10 watts (?). Anyways, my Dad built one up for the stereo upstairs and it can shake the house even though it only has an underpowered LM3886 chip which probably does 30 watts.
I also scored a big one when I remembered the Bang & Olufsen 90Watt RMS set that had been sitting behind my parent's bed for more than 3 years. I finally got my parents to let me use them (yay!) so I had a complete set of speakers.
Next came the amp circuits. I originally had this idea in my head that I wanted to build a tube amp. After a bit of Googling I cam up with several sites that sold tube amps. I found a push-pull stereo 8 watt amp for $150. Ouch. No way was I going to buy that!
A link on this site brought me to the chip amp section. That looked a lot better. There were some links to some sites with chip amp kits. After browsing the two listed, Chipamp.com and Audiosector.com, I decided that I wanted to get the dual mono-LM4780 kit. this would give me 120 watts per channel. I still had to make a sub amp, but I found a little amp chip that could do 30 watts if I built it right. When converted to USD, the price of the LM4780 kits is about 85 bucks. Not bad. Take that, tube amps!
Then, a trip to the Library yielded a goldmine. I found a book called The Audiophile's Project Source Book. This book had everything. Equalizers, Pre-amps, Filters, Protection circuits VU meters and more. The power amp that caught my attention was an L-MOSFET 100 watt design. There were some other BJT amps in the book as well but the L-MOSFET one sounded like the best. after doing some parts research, I found out that I would have to spend $50 in parts just for the driver MOSFETs. There were lots of other parts in the circuit that I would have to buy as well so I went back to the LM4780 kit.
I asked Mom one day if I could go and buy the kit, but she told me that I should probably wait a bit as I didn't have a job just then. I was too pissed to put 2 and 2 together and guess that I was going to get an amp kit for Christmas. Sucker! Oh well, I forgot about it until 3 days later when I opened up a present with two 50 watt per channel amp kits and a 48 Watt woofer amp. Well, that made the choice easier.
You can get these kits here:
Woofer Kit
Stereo Kit <-This is actually two of the 50w kits for a little less money.