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Making, baking, and (un-)breaking things in Southeast Michigan.

Physically complete, but not working…

August 9, 2007

Millett Hybrid Max w/12FM6 Tubes

Well, I’ve finished assembling the Millett Hybrid Max (photo gallery retired) that I’ve been working on. All that’s left to do is make the top panel and figure out why it isn’t working. All I know as of right now is that it is only putting out ~2.6VDC from the power supply. As there is a trimmer connected to it, and the trimmer was on the board when I washed it, I suspect that the trimmer got wet and a short in it is causing the voltage regulator to put out too little power. Hopefully it’ll work after a day or so, otherwise I might replace all the trimmers. I would ask for some help from the forum about these amps, but the forum is set up so that the admin has to approve every single user. I signed up, but I can’t post/reply because my account hasn’t been approved. Hopefully that’ll happen tomorrow.

Today was an interesting day otherwise. I left work a little early and headed out to that Tec-Ed place in Ann Arbor and did their market research thing. In short, I spent 38 minutes perusing Trend Micro’s Website and talking about it. I had to complete tasks like “what would you do if you wanted to download a free tool to do X?”

For all of that I was handed small stack of $50 bills. It worked out ot US$3.95/minute. Not bad.

After that I headed over to the Apple Store at Briarwood Mall in an attempt to buy one of the new Apple keyboards. The store doesn’t stock them, and wasn’t working, so I left and headed over to Zingerman’s Deli.

While at Zingerman’s I picked up a bagel and some cold brewed coffee for breakfast tomorrow, some Black Magic Brownies for a coworker, and placed an order for some dinner. This ended up being a bottle of Blenheim Ginger Ale† and Jen’s Pimento Party†† sandwich which I ate in the building next door to the deli while reading On The Edge. After finishing my food I also grabbed a 4 oz. cup of Zingerman’s dulce de leche gelato and ate it while sitting outside the deli at a picnic table.

After that I just headed home, went the wrong way at the M-14 / US-23 interchange, stopped to get gas at US-23 and North Territorial Road. After getting home things picked up with the amp.

Now, bed.

† Very spicy, and very very good. While it is made with real sugar, the presence of sodium benzonate and citric acid concerned me. Unless stored very warm it should be fine, though.
†† Pimento cheese (Southern cheese spread with Vermont cheddar and pimentos), Arkansas peppered bacon, tomato on grilled sourdough.

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Transistorize!

August 9, 2007

100 2N5087 transistors, sorted by hFE.

In order to ensure that the left and right channels of the Millett Hybrid MAX headphone amp sound the same I’m trying to ensure that all parts used in each are balanced. So, I ordered 100 pieces of each of the 2N5087 and 2N5088 transistors. I was able to get four parts which consistently metered identically, so those are used in order to ensure that the current to the tubes is kept consistent. For the other twelve transistors I was able to get matched pairs (at least) and ensure that the values are the same for each ear. That should work out well.

This evening I also figured out the template for the rear panel, drilled it, ensured that the parts fit, then put it together. I’m pretty happy with how all the parts fit, although I did have to shorten the heatshrink on the phono connectors so that the wire could bend better. When I test fit the PCB and the rear panel everything fits nicely, although the wires will be a little cramped.

Since I placed all the matched transistors, new 1/4″ jack, and replacement tube sockets I’m now ready to wash the board and finish it up. If things go as planned I’ll have it working either tomorrow or friday. Hopefully it’ll sound good, although I imagine that won’t happen until the tubes are burned in and biased, I’ve selected the tubes I wish to use, and it’s all done.

I also have to make the front panel (should be easy), potentially cut the shaft of the potentiometer shorter to fit the knob (risky, not really easy), possibly drill some arrays of vent holes on the top, front, and rear panels (easy, if I drill them right), cut the tube holes, and finish assembly. There’s also deciding on the set of tubes to use, so I’ll probably run it without a top at work for a while, but I’m not sure yet… That’s all up in the air.

Oh! I should also really make a photo to iPod dock connector cable… Or maybe I’ll just buy a new dock and use a phono to 3.5mm cable… Hmm….

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Tubes for my Ears

August 7, 2007

Getting there…

Well, the Millett Hybrid MAX that I’ve been working on is coming along. I ended up doing a few things to it tonight. First, I removed the tube sockets because I was going to fit new, hollowed out sockets and LEDs beneath the tubes. However, after some calculations I found that the LEDs connect right to the main 27V rail, and thusly the current limiting resistors have to sink a whole bunch of power. For the sake of not putting such a load on the power supply, simplicity, and a few other things I’ve opted not to illuminate the LEDs. (I would have needed something like 2W resistors.) So, new sockets will go back in place.

I also removed a bunch of the transistors. Because I want both sides to be balanced as closely as possible I ordered a lot of 100 of each of two types of transistors which can affect this. I’ll then match them and ensure that they are installed symmetrically.

Finally, I removed the 1/4″ headphone jack, because I decided I wanted a different type. I think I’m also going to put in a 3.5mm jack, just as soon as I have to place another order with Mouser.

I fitted a few of the new parts that came in, specifically some 1/8W resistors I had to purchase, because the exact required value of 1/4 watt weren’t available. 1/8W should be plenty for here, I think. I also fitted three more heatsinks.

Basically, as soon as my Mouser order comes in tomorrow I’ll have everything I need to almost completely finish the amp. Hopefully I can do so over the next couple of days. Sure, I won’t have the 3.5mm jack, but I can use an adapter for the time being.

I realized tonight that I’ll have to cut down the shaft on the really expensive, really nice Alps pot, but I think I can handle that.

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Giant PDFs in <36 Hours

August 6, 2007

Linking Microbial Diversity and Geochemistry
of Uranium-Contaminated Groundwater
(72dpi JPEG · PDF)

Screening and Characterization of Soil Microbes Capable of
Degrading Cellulose from Switchgrass (Panicum virgatum)
(72dpi JPEG · PDF)

Remember those layouts I was talking about yesterday? They are done. Finally. Besides work and sleep and showering and pooping I’ve worked on nothing else but these since I woke yesterday morning.

Except for the MAME Cabinet control panels, these are the first poster-size thing I’ve done, and they were done in an extremely short period of time for the scale of work (read: more than a bit rushed), but I’m pretty happy with them. My source material for them was two JPEGs, a word document containing content, and a couple of spreadsheets with unformatted tables and graphs.

These are posters which cover the work Danielle has been doing at ORNL for the past few months. They will be printed at 55″ x 36″ and will be presented sometime this week. Hopefully the presentation will go well.

Now I think I’m going to relax a little. I’ve got a monitor here to test†, but I might push that off until tomorrow.

† I picked up a Westinghouse LCM-22w3 for US$179 at Best Buy. It’s not a great monitor, but it has a DVI input, is huge, and was cheap. I’m debating using it for my MAME Cabinet, but I’m really not sure. If you are interested one, most of the local shops still seem to have them in stock. Here is the Best Buy page for the item.

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Layout Hell

August 5, 2007

So, Danielle’s down at ORNL, right?

Well, she’s needing some last-minute help doing layout on presentations so that they can be done in time to be presented on Wednesday or whatever.

Normally this wouldn’t be a big deal, but there were a lot of graphics I had to redo (they were given to me as low res PNGs), charts and tables I had to move from Excel to something vector-based, flowcharts to make, etc.

I’m only done with the first poster, the second one is about half done. I still have to get all the charts into it, get it flowing better, etc. However, if you want to see them, here they are:

· Linking Microbial Diversity and Geochemistry of Uranium-Contaminated Groundwater (Finished — 2.5 MB)
· Screening and Characterization of Soil Microbes Capable of
Degrading Cellulose from Switchgrass (Panicum virgatum) (Incomplete Draft — 4.7 MB)

I feel like a hack for using what’s basically the same layout for both, but I figure that the need for these posters is immediate enough that it’s okay for me to do. If I had two weeks and time to think and reanalyze and such they would be a lot better, but this is some stuff with a very immediate need.

A few minutes ago I just realized that I’ve been working on these for about 12 hours and haven’t showered nor brushed my teeth today. Yay!

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Finished!

August 4, 2007

Metering Power Consumption by two v2.0 RS232 to Eaton Leonard Interfaces
(Click for more photos (photo gallery retired)…)

Well, they are done. I worked for quite a while last night and for a good part of the day today, and all of the first production run of v2.0 RS232 to Eaton Leonard Interfaces is complete. They have all been bagged up and are sealed in a box waiting for me to deliver them in about a week and a half.

If you go to this page (photo gallery retired) you can also see a bunch of images I took of all the boards tiled together. These would be good for the background of product literature or something.

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Thickened Yogurt

August 4, 2007

Placing a bunch of yogurt on a coffee filter and then on a strainer is a good thing. However, I should not have tried to turn this thickened savory dish into sweet with the addition of cinnamon and honey. It’s not bad, but it doesn’t taste very good on an english muffin. :(

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Getting closer…

August 3, 2007

Missing LEDs and Power Connectors Only

Well, these are coming along nicely. All I have left to do tomorrow is install the LEDs and screw terminal power connectors, then I can wash and dry them and begin testing. Hopefully every single one will pass. They should, unless there are bad parts.

If they don’t, I’ve got a few spares of each part, just in case…

I also need to get some exercise tomorrow. I’m not yet sure what I’ll do, though… Maybe roller blading, maybe just a walk in a park. At least tomorrow is forecasted to be fairly nice weather-wise.

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