Well, it looks like I'm coming to this rather late, been checking this forum rather infrequently lately. Anyway, I just started folding on 14 CPUs: 6 P4 3GHz Linux servers, a dual 2.3 GHz XServe, and a few other older boxen. Too bad there's no Solaris client... Wonder if this would work with...

That's interesting, what did you use for the source and output with the Airport Express? Being a *nix sys admin, I keep the PB near at all times, ssh/X11 and all that... Not that it's much of a burden This comparision was more for my own benefit, and it turns out that I should always...

My iPod (40 GB, 4th Gen) was in serious need of charging, so I grabbed the Firewire cable and plugged it into my 15" PowerBook (1.5 GHz G4). iTunes popped up, so I figured, why not take a listen (using the Ety ER-4P). Note, all songs were being sourced from the iPod, and all are MP3s at 256...

$400 for a pot, ouch. The 40 step TKD stereo attenuator that I got for $250 from Percy Audio a while back, and never got around to using until now, seems like a good deal suddenly. Kevin, how good is that pot in comparison to a stepped attenuator, esp. one with a large number of steps like...

I don't know if lowering the 100 ohm is a good idea, won't that increase the current through the second stage transistors? They are fairly warm as it is. Would increasing the current source 500 ohm resistors help? I notice that if both trimpots are lowered the current shoots way up, should...

I have access to a machine shop, so the brackets were roughed out on a bandsaw and cleaned up on a mill, though a coping saw and sandpaper or a file would also work if hand tools are all that's available. Also, flattened the mating surfaces on the bracket and heatsink using a beltsander and...

Measuring along the outer edge of the bracket: the transistor leg is 1.1", the heatsink side is 2.8". The width is 5.6", the extra inch over the HS-TWS width is to allow for chassis attachment, though I haven't drilled the holes for this yet.

Trevor, DigiKey doesn't stock Wima, but the BC MKP metallized polypropylene is almost as good, part BC2083-ND. The 10k pot is CT9W103-ND. Also, I used a silver-mica 33pF, 338-1047-ND.

Got the 1/4x3x3" angle Al from speedymetal on eBay. S&H is kinda high, but I really don't need 8' of the stuff, otherwise I would have gotten it from McMaster-Carr. Here's a better pic of the heatsink assembly. The conical washers have a bonded rubber part, might remove this, also need...

tangent, I am sure you are correct, the second version of the circuit I put out there was untested. I agree that a bandgap ref will work much better than a weak-in-the-knee zener; while most cost significantly more than standard zeners, the LM385 is one of the few competitively priced ones out...

Not the best photo, being on the bench, but now that I finally got the transformer this project is coming together nicely... On the top is the unregulated stage of the power supply (the part outside the box in my schematic), fits perfectly on a RadioShack 4-1/2 x 6" perfboard. The bottom...

Quote: Originally Posted by RickP Wouldn't you want to consider NOT anchoring the board tightly due to the thermal expansion and contraction of the heatsink/angle assembly? This might lead to fatigue and failure of the output transistor bodies. Perhaps using flexible fasteners (spring...

Quote: Originally Posted by strohmie Only missing one part for mine, the large caps (I bought some Nichicon MUSE caps but didn't pay close enough attention to the diameter -- anyone have a good cap they can recommend?): I used Panasonic FC 50V 120uF, DigiKey part P11255-ND; 10mm...

Here's a minimalist version of my tri-color comparator circuit, should be able to put this together for around $2 (including the LED, Lumex SSL-LX3059IGW is $0.75 from DigiKey).

A clipping dectector would not be good in my case (DAC). NiMH batteries have a "safe" range of at least 1.0V/cell to keep any one of the cells from going into deep discharge, even at this "dead" level I still have a volt or two above the regulator dropout level.

Quote: Originally Posted by tangent Even better, an LM317L, adjustable version. If you're going to spend more than a zener, I think you should get finer adjustment than 1-3V between steps, which zeners do provide. I don't see the advantage of an adjustable, the only reason to use...

Quote: Originally Posted by tangent The use of a voltage regulator as a reference is an interesting tradeoff. Yeah, a 78Lxx would be cheaper and is available in a wide range of voltages, the LT1121 is just what I had in the parts box at the time, and a zener ref will be the...

This is what I built a few months back for my DacKit 12V 10 cell NiMH battery. >12V green 11-12V orange <11V red

My (hopefully) final draft of the Gilmore-Didden-Jung tracking regulator. R15 & C13 may not be necessary, I included them for equal opamp input impedance and symmetry. Shouldn't be too difficult to convert back to a more standard (non-tracking) Jung super-regulator, if that is your preference...

pooooo, why did you include the darlingtons? A LT1085/1185 reg pair will do 3A each. [Edit] and should have better ripple rejection and lower noise, important since the final stage opamps are supplied from this.

Digi-Key has several cheap models, these are all +/-5% load regulation (or unspecified). Tighter specs are quite expensive, only desk-top line Condor makes is the GXM60 Series, the 24V@2.5A +/-1% load regulation is $105, part# 271-2224-ND. The Elpac MW24 series is a +/-5% model.

A warning about the HS-TWS, turns out the web page dimensions have a typo, the fin height is 29/32" not 2-9/32". My rough calculations give about 2.5 °C/W, should still be plenty for 15W, so I think I'll keep them without complaint. I snapped a photo to give a sense of the size, the heat sink...

I got my heatsinks from here: http://www.surplussales.com/Heatsinks/HeatSink1.html TrevorNetwork, try looking for the OPA27, the OPA177 will work as well. The latter is cheaper with slightly better offset and drift specs, though a bit noisier.

I haven't gotten the transistors yet and was wondering if the package on the 2SC3421 and 2SA1358 is all plastic or metal backed? Will they need to be electrically isolated from the heatsink?

I stumbled across Mr. Gilmore's sketch of a dual tracking version of the Diden-Jung regulator recently [http://gilmore.chem.northwestern.edu/kgdidenjung.gif]. Adapting this circuit to supply the Dynahi amp seems doable. Biggest obstacle is the high voltage opamp, needs to handle at least...