Discussion in 'Electronic Basics' started by [email protected], Jul 16, 2007.

1. Guest

Can anyone explain why turning on another load in an electrical system
causes the others to diminish in intensity? I notice in my car when
it's running that the transmission indicator display dims and
brightens with the on/off pattern of the turn signals. Is this
because the extra amps result in an inability of the system to
maintain voltage? How could this be if the car has so many other
loads to carry on the system and the alternator compensating? I also
have seen the same thing at home. My microwave light and timer
display dim and brighten with the on/off of the microwave power during
reduced power cooking. This too seems odd even though its so many
watts because I am not using the maximum amps for the breaker.
Additionally, the whole house could surely be demanding more amps on
the utilty company's power supply, as could the community. Is this
for some reason a strain on 120V?

2. ehsjrGuest

Using the car as an example:

A
+12 ---[R]---+---> to turn signal
|
+---> to transmission indicator

[R] in the above diagram will lower the voltage at the
point labeled A by an amount equal to the current drawn
by the turn signal times the value of R. R is the
resistance in the wiring, fuse block and connectors between
point A and the battery. When the turn signal is off it draws
no current and the voltage at point A is higher because no
voltage is dropped in the resistance. When the signal turns
on, it draws current through the resistance and the voltage
at point A lowers.

Ed

3. neon

1,325
0
Oct 21, 2006
Th battery is the source of the power actualy the generator if running Those two items have very low inpedance and generaly don't move voltage wise with light load like a couple of amps If you see dimming is because the wireing of the car IXR drop makes it so. car manufacture is at fault by not providing proper wireing and that is the fact. same thing in your house if the heavy use appliances comes on and the wireing is in series wih another load it will dimm because of IXR drop. To mae things worst some apliances have a heavy inrush current.