Sunday, May 29, 2016

Filament Boards.

Hey... where have jeffrey and dave been???  Well the answer to that is busy.  To add at least a little content to this miniscule corner of the web, here is one of the small things I have recently made.


This is a "keeper" board that attaches to a pc mount bobbin and holds a schottky bridge and a pair of caps for a choke input filament supply.  The chokes are dual bobbin and wound with flat wire for choke input duty and have split windings so one leg goes in the + side of the supply and the other in the ground.  The PC mount bobbin allows for a nice way to hold the needed parts and the whole thing is supported by the mounted choke.


The ultimate use of these boards is for providing DC to some coleman regs and here is the resulting waveform when drawing an amp and a half of current.  Yes that is a 60mv p-p 120hz sine wave


Finally a picture of what is really going on.

Tuesday, April 5, 2016

Shielding SUT's



One of the biggest problems with rolling your own SUT is shielding them to get them quiet.  In the very near future I plan on offering two options to help the cause of the DIY'er for shielding.  One is a Steel box that has holes for RCA jacks and a ground lug.  This can be lined with mumetal and copper foil for an effective enclosure.  The other is a deep drawn mumetal can that can be placed end to end  for a final shield.  These can then be put inside a steel box for complete shielding.


Tuesday, March 1, 2016

Elmaformers

It is such a task for people (including myself) to solder the $400 autoformers to a switch so I am doing a circuit board that wires them directly to an elma switch.


While not being the smallest of finished items, it fits together nicely and can stack for as many decks as needed which makes true balanced operation a breeze.


This is a simple two deck "proof of concept" on proto boards with a 24 position switch that can have any desired taper you choose.  They will wire up lust like a traditional pot with In, Out and Ground connections for each deck.  I am so happy with the results I am planning another version on the 47 position switch that can have 1dB steps.


Sunday, February 28, 2016

From Russia With Love


So I receive a belated holiday present from a friend and it comes in a box with cyrillic letters on it so I get a bit excited.  When I open it, my first thought is why the hell did Fred get me an ugly red sweater?


Upon closer examination I quickly realize that there is something hiding inside that sweater.



Ahhhh,  now I feel much better but I am still really confused why this sweater used as packing has no armholes.  This naturally brings me to the conclusion that this isn't a sweater but a Soviet Era method of packing valuable tubes.  (take that eimac!) While the boys were having fun playing with the "armless sweater" their mom comes in and asks why there were playing with a skirt? We all need to go out and mow the lawn now.... or work on the car.... or something.....

Sunday, February 7, 2016

Random says 10

Random picked 10 as the winner.





drop me an email with your address and they will find their way to you.

dave


Tuesday, February 2, 2016

Freebruary


Just got these back from a vendor and they need a new home.  They are the current modules and have a cheap pair of interconnects soldered into them for a quick audition.  I'm leaving them as is and it is up to the lucky winner to decide what to do with them.

Leave a comment below with an identifiable name and Random.Org will pick a winner in a few days.



Thursday, January 14, 2016

Micro-Bomb



I finally sourced some MuMetal cans that are big enough to house the SUT's.  Two of them will fit together to house a pair and a band of adhesive backed mumetal holds them together nicely.

While not exactly small it goes a long way to getting the required shielding to package these things up.  Simply add a steel box,  some RCA's, solder and enjoy.

dave