resistief netsnoer (Techniek Radio/TV)

door Oldtimer , Oegstgeest, 26.06.2018, 17:19 (2347 dagen geleden) @ kris

18 Watt dat is al een redelijke warmtebron.
Daarom dat de condensatormethode beter is.
Berekenen van de nodige C ipv de weerstand is echt niet zo moeilijk.

Inderdaad, dat is niet moeilijk...
Op de website van Gerard Tel, zie:

http://www.staff.science.uu.nl/~tel00101/FotoAlbum/RadioCorner/

vind je in de linker kolom onder 'Featured articles 03 ACDC sets' bij het omlaag scrollen o.a. dit stukje:

Some more technical points regarding the AC/DC radios. The heaters of the (usually four or five) tubes are connected in series. In the European radios the common heater current is 100mA (tube type numbers start with U), while in the American radios (like this RCA) the current is usually 150mA. The heater voltages add to usually 110 or 120V. In those radios that can be played on 220V (almost all European radios) a large dropping resistor is used in series with the heaters. This large resistor dissipates about 10-12 Watt and becomes very hot. It sometimes contains asbestos.

When the resistor needs replacement you can put new resistors, but it also becomes increasingly popular to put a series capacitor instead; compute the value with the CapCalc spreadsheet in 10 seconds! (Requires Excel.)
I did so in my Philips 208U to reduce the amount of heat produced in the small cabinet.

Dus even CapCalc aanklikken in de originele tekst, de gevraagde gegevens invullen en klaar is ...

Willem