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Old 1st June 2012, 02:30 PM   #91
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Quote:
Originally Posted by tubelab.com View Post
E) None of the above...
E ?!?!?! What happened to C and D that I didn't even think of?

Oh, man. I just flashed back 26 years to my physics 101 mid-term exam where the professors created a multi-choosey exam; 12 questions with most pre-loaded with "common mistakes" that the great unwashed will often make in their leap to an answer. In many cases, my fellow students were beaten by statistical "monkey" that would randomly choose and get more than 25% correct OR the one guy (this is true) had a total brain fart before the exam, created a pattern and hit that "one in a million shot" and got 12 out of 12. Lucky S.O.B.
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Originally Posted by tubelab.com View Post
I have made adapters before. You want pins that have to be staked into the board. If you rely on solder alone, the joint will eventually get brittle and go intermittent with repeated use.
The ones I was looking at are mechanically swaged into vias in the board of a specific hole diameter (a few thou over). So, these would be mechanically held on both sides of the board. There are also the stake type/press fit, but I think I'm happier DIY'ing a swage fit than thinking about the possible creaking and cracking sounds of a pressfit going awry if the board is not supported enough from behind...I suppose some kind of mini-arbor press thingy might do the trick. First things first though, can Novar/Duodecar circles intermingle in a nearly aligned fashion. Then, I split the atom at my kitchen sink and cold fusion will soon follow.
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Old 1st June 2012, 04:20 PM   #92
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Originally Posted by tubelab.com View Post
I have made adapters before...
The trick for the 6LU8/6LR8 adapter appears to be that although the guts of these tubes are the same, the pinouts look like pick-up-sticks.

In trying to keep the filament pins pointing in the same direction (Novar 4,5 to the Duodecar 1,12), I am seeing some sort of weird Kama Sutra type intermeshing circles that could work without too much offset and the trace lengths are not too long from the grid stoppers and cathode resistor for the pentode section and the bias diode for the triode section.

Still might work if I can find an ideal angle for clocking the Novar tube pin circle that would align with the socket below. Making progress anyway. It's raining here and it feels a bit like The Shining...all duodecars and no play makes Jack a novar boy...
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Old 1st June 2012, 08:36 PM   #93
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The trick for the 6LU8/6LR8...the pinouts look like pick-up-sticks.
OK...have an adapter if anyone is interested. The attached ZIP file holds a FreePCB layout file for a two-layer board 5mm by 5mm (can be considerably smaller if needed) that allows the soldering in of a Duodecar socket and press-fit or swage micro pins for the Novar.
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In trying to keep the filament pins pointing in the same direction (Novar 4,5 to the Duodecar 1,12)...Still might work if I can find an ideal angle for clocking the Novar tube pin circle that would align with the socket below...
The ideal angle appears to be minus 5 degrees or so for Pin 1 of the Novar at 3 o'clock (i.e. "zero degrees" in trig parlance).

The pin circles interlace. The tricky bit is that the Novar has a tube pin circle of 17.45mm and the Duodecar 19.1mm. I found Duodecar sockets on the web with an advertised PC mount pin circle of 20mm to 22mm and used that as a basis. Clearly, if a wider footprint for the PC mount side of the Duodecar were available from a reliable source, the B9E Novar circle of pins would be much, much easier to fit within the Duodecar.

On to something else as useless. Good practice in FreePCB and high school trigonometry though.
Attached Files
File Type: zip Duodecar2NovarAdapter.zip (3.4 KB, 6 views)
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Old 1st June 2012, 08:45 PM   #94
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OK...have an adapter if anyone is interested...
Oh...just realized from an earlier post we might also want to know the transcription of Duodecar to Novar pinouts 6LU8 to 6LR8:

Novar B9E (pin#) Function Duodecar B12C (pin#)
1 Triode Cathode 11
2 Pentode Grid 6 & 7
3 Pentode Cathode 9
4 Filament A 1
5 Filament B 12
6 Pentode Plate 4
7 Pentode Screen 8
8 Triode Plate 2
9 Triode Grid 10
-- Not Connected 3 & 5

Trust I got this right from the respective data sheets. I suppose short runs of insulated wire to a chassis mount socket would permit the use of a B12C socket with the Novar based PCBoard.
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Old 2nd June 2012, 12:36 AM   #95
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Default Socket Adapter

To all:

Attached is a better version. I found Peter Millett's Duodecar (6LU8) socket source (among a few), which has a PC mount pin circle of 25.4mm (1.0 inches). With the 17.45mm specification for the B9E socket pin circle for the Novar (6LR8). This is a slightly more elegant arrangement than my earlier post/attachment.

Nice to have the option for 9 or 12 pin for the Spud so one can choose based on available stocks from your preferred suppliers.

Working it the other way (9 to 12 pin adapter) is a much bigger challenge, in my estimation.

Time for a Pikesville and water...TTFN
Attached Files
File Type: zip Duodecar2Novar_Adapter_r0.zip (6.3 KB, 7 views)
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Old 2nd June 2012, 12:47 PM   #96
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Originally Posted by tubelab.com View Post
E) None of the above.

In order to maintain electrical compatibility with the dual SE option a single driver stage must remain connected to each output stage. There is exactly one way to do this. Currently there is a resistor and a capacitor to ground on the cathode of each input tube. You add a jumper so that the two cathodes can be tied together, then add a CCS to ground. This creates an LTP...
Since I am trying to learn about the circuit designs along the way, are you talking AC coupled or DC coupled Long Tail Pair as described here: link

So, IF I have deciphered the DC coupled LTP correctly, the mod to be made would use the Triode sections of both 6LR8 tubes to create the differential pair phase inverter and voltage gain stage that would pass onto the two pentodes in the output stage in a push pull setup.

More coffee this AM might make this even clearer...or muddier if I am off base on my decryption of the circuit. Why oh why can't this be a fuel or ignition map from a powertrain control module? THAT I understand.
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Old 4th June 2012, 11:51 PM   #97
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If this board goes ahead, when may be available?
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Old 5th June 2012, 06:24 PM   #98
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If this board goes ahead, when may be available?
It looks like some version of this board will happen. When, is a hard question to answer. I have a full time engineering job that consumes most of my time. Tubelab is a part time venture that barely covers its expenses. To fix this, I have decided to eliminate the warehouse rent by closing out the warehouse. I have already informed the landlord that June is my last month. This gives me 25 more days to remove all my stuff. I will be very busy moving stuff until July.

After that I need to fix by messed up website, re-do some of the instructions for the SSE to match the new board revision that is coming.

I still need to finish the design work and testing on the Spud SE board, re-do the layout, get some boards made, build, test and document them, and create a set of build instructions.

The reality of all of this work says that a fully finsihed board with a parts kit and a proper set of instructions is still several months away if no major interruptions come my way. A few boards may be available to early adopters sooner. These are for the porpose of finding potential problems, and verifying the instructions and parts kits.

Quote:
are you talking AC coupled or DC coupled Long Tail Pair......use the Triode sections of both 6LR8 tubes to create the differential pair phase inverter and voltage gain stage
The concept is to use the two triode sections to create an LTP similar to the one shown in your link. Exactly how it will be biased hasn't been determined yet. The DC coupled variant has the grids at DC ground and a negative voltage on the CCS feeding the cathodes. This requires a negative voltage source. The AC coupled variant has the cathode CCS tied to ground and the grids fed from a posithve voltage source. This requires a second set of coupling capacitors in the signal path. I will breadboard both variants and test them, but I would prefer not to add more caps.
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Old 6th June 2012, 12:22 AM   #99
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Understood, IŽll be waiting and count on me for three PCB.
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Old 8th June 2012, 08:11 AM   #100
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