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First spider done.

Posted 27th March 2010 at 06:40 PM by Bas Horneman (Bas Horneman's blog)
Updated 14th February 2011 at 06:51 PM by Bas Horneman

The Takman resistors have thick copper wires. This makes for wonderfully strong little spiders.

I've also used ceramic terminals strips for the first time and it makes for a nice strong construction.

And I did the ccs for the phase splitter a while ago.

[edit] I used silver solder. But found out that it is NOT necessary with these fakes. Fake or not it make for a great construction.

Tektronix first developed and used ceramic strips in their oscilloscopes in 1952. During the manufacturing process, silver in liquid form is painted in and on the notches of the strips prior to the application of the final glaze and final firing. The silver is then firmly bonded to the ceramic and wires can be soldered directly to the ceramic.

Special silver-bearing solder should be used when soldering to ceramic strips so the silver bonded to the strip does not...
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for pmillet sound card interface

Posted 18th March 2010 at 06:09 PM by klewis

Tonight I found out it is a really good idea to ground the shaft/body of the rotary switch in order to eliminate pick up of 60Hz and its harmonics. I noticed moving my hand closer to the metal knob on this switch resulted in a >20dB increase in 60Hz spectra and the addition of somewhat lower level harmonics at 120Hz, 180Hz, and 240Hz.. I grounded the switch with a piece of 28ga wire between the lock washer and the body of the switch and grounded it to the board ground. This totally eliminated any pick up with no noticeable line frequency or related spectra. (My case is totally shielded on the top and bottom, but not sides, front or rear - and does not appear necessary to do so.)
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maudio thread

Posted 18th March 2010 at 02:57 PM by klewis
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Side tracked

Posted 18th March 2010 at 12:28 PM by jtktam (Newbie audio DIYer)

I have been side tracked lately. not enough time to do the F5 like I wanted.

I ended up digging up the BOM for mini aleph and ordered the parts for that.. started to solder the parts and found that I needed to soldier mount the resistors because they are way too big for the PCB

I need to double check all the blank spots, clean up the flux on the board and start on the power supply..
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YARPS (Yet another regulated power supply) updated 2012/01/02

Posted 18th March 2010 at 11:30 AM by wintermute (Wintermutes Rantings)
Updated 2nd January 2012 at 10:24 AM by wintermute (added formula as well as a few other minor edits)

10 Feb 2011. AndrewT pointed out something really dumb I had done (in a most polite way) in the original circuit. The caps in the filter section are in series and effectively halved in value. The circuit will behave much better simply by deleting half the caps. I've uploaded the latest version of the file. Sorry to the 125 people who have already downloaded, and I hope I didn't cause too much head scratching as to why I had done that, I'm not even sure myself, and I'm surprised I never realised. I'm going to revamp this blog entry as there are some things I have realised since I first posted, but that will be over the next couple of weeks. Hopefully I will finally build it soon.

I have been spending an inordinate amount of time using LTSpice lately. The more I use it the more I like it! For someone like me who is somewhat challenged mathematically, and who's electronics theory knowledge level is well below where it should be (to be doing this sort of design anyway),...
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reforming capacitors

Posted 16th March 2010 at 02:50 PM by klewis

from AndrewT

Apply 16Vdc through 100k resistor and measure how the resistor voltage varies with time. The resistor voltage is a rough indication of the cap leakage+charging current.
Once charging is substantially over the remaioining current is predominantly leakage +-a little bit of chage/discharge current depending on the stability of the supply.

The apparent leakage is very much affected by the DC supply voltage. A good regulated DC supply that is held at constant temperature will help a lot.

You may find that 6hours at 100k gets to within 105% of the ultimate leakage current. But tell us what you find.

You can reform a bank of caps using one resistor to feed each capacitor.
Measure across each resistor to see how similar or different the caps are.
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Sound measurement software

Posted 15th March 2010 at 08:05 PM by klewis

this one seems to seperate THD from noise
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shielded wire

Posted 15th March 2010 at 05:36 PM by klewis

Use RG58 on all your shunts for sense wiring. Use as thick main ''force'' wiring as you like. Remember that the sense nodes are voltage nodes, don't worry about gauge. Their mission is to skip the voltage drop on the current carrying force wires and ''see'' the remote nodes directly. I believe that you will see less stuff on your scope in difficult termination situations if you shield your sense wiring. If you need extra thin and flexible enough, see about Belden (RG style) 179DT also, which I like for signal too BTW.
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new kid

Posted 12th March 2010 at 04:18 PM by Nathan61

I have been tinkering with speaker ever sense I was a kid back in the seventies and have always been trapped in the box. My newest efforts are an improvement but remain in the box Durring the last 6 years I have visitd this site for ideas and must say thanks for all I have picked up. My system is now compiled of all dyi speakers and is a vast improvement over the commercial systems I have purchased over the years “due to lack of funds to buy the good stuff of course.” I have over the last few years tried a few open baffle approaches with little success. The back loaded horn with the fostex sounds great but it’s a little to honky for my taste. The small box using silver flutes and vifa tweets crossed at 2.5k and dampened using automotive damping pad made of polyester and kanaf “I have access to many exotic damping materials” sound good but appears to fade in and out (I need help with this one) I used decent crossover components Bennic caps and jantzen 18 ga air core ind. all connections...
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measuring current across diodes

Posted 6th March 2010 at 03:09 PM by klewis

Do you know what is the Vf of your LEDs? R1 should be roughly equal to (3 x Vf) / desired_current. So for testing, if your LEDs have Vf = 1.8V or even Vf = 2.1V, and we're aiming for something around 20mA, then you can use R1 = 300R.

For 1.8V LED
I = 3 * 1.8 / 300 = 18 mA

For 2.1V LED
I = 3 * 2.1 / 300 = 21 mA

The 300R resistor can be 1/2W or whatever you have around.

You will know it works well if you measure the voltage across R1 and divide it by 300 and if the result is close to about 20. Of course you should see the LEDs on.

Try to implement just the CCS portion with a 300R for R1.
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