feeling really dump...

ilan

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Hi everyone,

I wanted to demonstrate my kids a simple electric circuit with a motor and a lamp. I remember I learned in school 25 years ago how it works but now I feel very much like this:

I was assuming that the lamp AND the motor will run as soon as I press the button but what happens is only the motor is running but the lamp is off. why is it like that? not enough power to do both? and if so why is not the lamp on and motor is off?

any explanation would be very appreciated

 

Cableguy

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A lamp is a resistance, that turns incandescent when a "high" enough current flow through. The motor on the other hand is an impedance, usually "high" impedance, but with a low resistance value. (That's why if you mesure résistance it will beep since it basically a long copper wire)

So, the impedance of the motor (Hall effect, I think) is preventing enough current to flow through the lamp since you have contacted them in series.
I would expect a different behaviour if connected in parallel!
 
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Star-Dust

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The electrical energy passes where the device does less impedance, as happens for a short circuit.
You should put a light bulb and a motor that have the same resistance in ohms, or better if you connect them in parallel and not in series.

Connecting them in parallel (lamp and motor) you will have less light intensity and fewer revolutions, but both will work
 

Star-Dust

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You're too fast, I didn't have time to answer
 

ilan

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Cableguy said:
HERE and a "to the point" explanation...
Click to expand...

thank now i understand. and you think that could work? i remember that in school i was teached that electricity is always seeking for the shortest distance to pass so for me in a parallel circuit i would assume that only 1 lamp will light and not all three. but i guess i am wrong?

 

Star-Dust

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When it refers to a shorter path it is not meant in centimeters but relative to the resistance it finds. A greater resistance is a longer path.

But in parallel the current will divide proportionally, there is also a formula to establish it, but it is not the context to talk about this
 

Cableguy

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Imagine the wires as water pipes… and each device (lamp and motor) as botle-necks...
in a series , the first botle neck will reduce the water flow that the next device will receive, while in paralel, all botle-neck receive the same amout of water!
Water, in this case, is current, and since both your devices are "basically" résistors, they also introduce tension-drop!
 

ilan

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thanx a lot cableguy and star dust. i have learned something new today
i wish i had listen more carefully at school 25 years ago
 

Cableguy

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ilan said:
thanx a lot cableguy and star dust. i have learned something new today
i wish i had listen more carefully at school 25 years ago
Click to expand...
A small "payment" for all I have learned with you over the years here...
 

ilan

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btw both of you were right, parallel connection works for both
i even don't accounter any drop, lamp is bright enogh and motor spins fast.

 

ilan

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Cableguy said:
A small "payment" for all I have learned with you over the years here...
Click to expand...

thanx cableguy, i am sure i can learn a lot from you about electricity. we spoke long time ago about that topic and you were very patient and explained it very well. i am very happy to meet people like you in the forums.
 
S

sorex

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see serial as spreading your source over several things. a good example to remember is these electrical lights that people put in their christmas trees.

a lot of small resistance lamps don't need additional resistance or power supply.
lets say a 100 lights version where each light gets 240/100=2.4V.

parallel is equal like in a living room roof light source with 4 or more lamps where all lamps get 240V.
 
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ilan

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f0raster0 said:
then now that it is working you will add a module bluetooth to turn on/off the lamp and motor with your B4x App
Click to expand...

acctually i was thinking more of an atom bomb. but maybe i will start with a simpler project.
btw has anyone created a game with b4r? if not, i will do one
 
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