radiomuseum.org

 
Please click your language flag. Bitte Sprachflagge klicken.

philips: Philips 2502;

Moderators:
Martin Renz Ernst Erb Vincent de Franco Martin Bösch Mark Hippenstiel Bernhard Nagel Otmar Jung Heribert Jung Eilert Menke 
 
Please click the blue info button to read more about this page.
Forum » Radios and other type of sets (Physics) etc. » MODELS DISPLAYED » philips: Philips 2502;
           
Francisc VISKY
Francisc VISKY
 
RO  Articles: 96
Schem.: 9
Pict.: 376
23.Sep.07 20:20

Count of Thanks: 42
Reply  |  You aren't logged in. (Guest)   1

The valve F215 is very difficult to find it. So I decided to replace it with E433. But there is a difference in heating voltage: for F215 is 2.5V, 1.5A and for E438 is 4V, 0,8A.

So I decided to build a small transformer from 2.5V to 4V. Calculating, I obtained: Q=2.5 cm2, n1=20 turn, 1 mm in diameter and n2=68 turn, 0.6 mm in diameter: n1 is connected to the transformer and n2 is connected to the filament of E438.

You can see in the picture attached. The only difficulty is a good shield for the transformer to have no influence in the audio circuit.

MH: I took the liberty of rendering this text anew for legibility. Regards, Mark

Attachments:

This article was edited 24.Sep.07 08:30 by Mark Hippenstiel .

  
rmXorg