[Winky Dink]

Been working up an Echophone S-4.  It's a 1930 6-tube TRF.  I have one filter cap to replace with an electrolytic and I can't decide on the proper positive-negative orientation.  Actually, I made that decision and soldered in the electrolytic, but I don't want to find out that I was wrong.

It's the 2 uF cap circled here:  If this isn't legible, a direct link is:  https://flic.kr/p/2cWipKg



[Image: https://farm5.staticflickr.com/4908/4590...9d10_c.jpg]



Now, the Show & Tell.  I bought some DIY water slide decal paper a few years ago.  I've used it successfully a few times, but this is the application that I originally envisioned.  The dial face of the Echophone is rather...ugly.  I masked and repainted it:

[Image: https://farm5.staticflickr.com/4901/4408...8988_z.jpg]



Printed a decal for the full length of the 0-100 numbering.  Cut the finished decal into three sections for easier application.  When the decal dried, I coated it with clear enamel. 

[Image: https://farm5.staticflickr.com/4861/4590...de02_z.jpg]

Ta-dah!  Couldn't have turned out better if I'd done it myself.  Hope this can help someone some day.
Thanks for the advice on the electrolytic capacitor placement.

- Henry

[Steve Davis]

Henry, on your schematic, the left side of the 2uf capacitor is the - 

Steve

[KCMike]

Nice job on the dial

[Winky Dink]

Thanks, Steve. I did this one right. I usually get about 50% right.

[Phlogiston]

I used that method to recreate the clock face on my Westinghouse Columnaire.

[klondike98]

I tried the DIY water slide approach once and the decal was so fragile I could not make it work...maybe I had a bad product. Both of those applications look great!

[Arran]

Henry;
  I would go back and replace that 2 uf with a non polarized capacitor, either a large film cap or a motor run cap, modern low value electrolytics apparently can't take the ripple current found in old radio power supplies and don't live very long. The originals were probably large paper capacitors to start with, sort of like a Radiola 18 or a Philco 20, not electrolytics.
Regards
Arran

[Phlogiston]

Henry;
  I would go back and replace that 2 uf with a non polarized capacitor, either a large film cap or a motor run cap, modern low value electrolytics apparently can't take the ripple current found in old radio power supplies and don't live very long. The originals were probably large paper capacitors to start with, sort of like a Radiola 18 or a Philco 20, not electrolytics.
Regards
Arran

This is good advice. The Solen 630V caps are available from AES. I use them in all filter applications up to about 20uf.

[Ron Ramirez]

Yes. Thanks to youse guys I'm using Solens now.

[Arran]

I've heard good things about the Solens, but you can even find those generic yellow polyester caps in 1 and 2 uf 630 vdc sizes these days, I don't know if they go higher then that. Another option is a series of Panasonic film caps that Mouser sells, those go up to 3 or 4 uf, at 630 vdc, and are fused so they won't short out. I can't remember who made them but there was a type of film cap that Bob Andersen used inside the filter caps of his Philco 115DX, they were like red or brown drops, which he connected in parallel to add up to whatever he needed, but those were Mershon cans so they had the room inside. The point being is that thanks to improvements in materials and manufacturing processes, you can make filter cap changes a thing of the past in many pre war AC radios. In something like this Echophone, or the similar Dictator (Gloritone clone) I have why roll the dice with an electrolytic when 2 uf film caps are relatively inexpensive and available?
Regards
Arran