using lamp as resistor

Status
Not open for further replies.

thebadtall

Full Member level 6
Joined
May 17, 2012
Messages
339
Helped
12
Reputation
24
Reaction score
12
Trophy points
1,308
Location
Hellas
Activity points
3,605
Hello, I measured a typical lamp and is 100Ohm / 40W
Can I use it as replacement of a high wattage resistor of same value ?
Thank you
 

The resistance when an incandescent bulb is cold is about 1/10 of the resistance when the lamp is on and the filament heated.

A 100 ohm resistance would results in (220²)/100= 484W
for 40v @220v the operating resistance is R= 220² / 40 = 1210 ohm
 

Such a device can be used - for example - as a non-linear gain controlling element (with positive temperature coeff..) in harmonic oscillators. In fact, it was used by Mr. W.R. Hewlett in 1939 to stabilize the world's first WIEN oscillator.
 

P=V*I and I=V/R so you can write P= V * (V/R) = V²/R
If you solve for R then R= V²/P

V=220v
P=40W

R = 220²/40 = 48400/40 = 1210 ohm

Alex
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…