sshsslfun

modified 7 years ago

Loads Test

179

02:29:33

This is something I have wanted to do for a while. Each circuit compares different loads, from left to right, the first one features a resistor load, the next one a lamp, and last an LED.

Each load has been configured for 150 ohms@3Volts which equals to 20mA@3Volts.

So, my conclusion:

LEDs are LEDs, they do not represent loads such as lamps, drivers, circuits, etc. LEDs are to not represent a load that isnt an LED.

Lamps and resistors behave the same way, as I've concluded from this test. Maybe because lamps use filaments which have their own resistance acting as resistor that its lumenosity changes by the voltage and current going it.

I might be wrong about some of this, what do you think?

published 7 years ago

kiani

7 years ago

The v/i curve or display gets confused, if you try different ciruits on it at the same time,, the lamp is showing non linear behaviour,, but it is only cause you are monitering two separate circuits,, if you do it one at the time then the lamp is linear..

sshsslfun

7 years ago

Yes, I wanted to do that but EC only allows 4 channels, it looks nonlinear but it is.

hurz

7 years ago

Read description http://everycircuit.com/circuit/6552124912828416

sshsslfun

7 years ago

Thanks @hurz!! Ill do that then!!!

jason9

7 years ago

In EC your assessment is completely correct. In real life, the resistance of an incandescent bulb is highly temperature dependent, and the temperature is a function of the power dissipated in the bulb with a delay that can be modeled by a simple RC circuit. This means that doubling the voltage will not double the current. If you were to take the x-y plot of an incandescent bulb (slowly enough to keep the temperature from lagging behind the power dissipation) then the plot produced would be steep at low voltages and flatter at high voltages (low resistance when cold, high resistance when hot). It would be like the inverse of an LED. The resistance rises with voltage rather than dropping.

hurz

7 years ago

The resistance of most metals increases with temperatur PTC you can even use a bulb as temperatur sensor. Measure the resistance and heat it up by your hands if you take from the fridge. The opposite behaviout would be a carbon filamente bolb, Edisons first bulb decrease resistance for higher temperatur you can imagine what problems that might cause while PTC does regulate by itself a carbon lamp needs some care and stable voltages. The NTC slope is abosult more then a decade smaller then the PTC increasing effect.

hurz

7 years ago

Here a grap, unfortunately with diffetent powerful bulb 1:3.75 anyway impressive https://www.flickr.com/photos/tubetime/1582918380

kiani

7 years ago

One then could argue that a resistor + remperature is an active componet.

kiani

7 years ago

...temperature + time+ resistor = active component ,,?!

kiani

7 years ago

There are three terminals,, ,, pick input, output and control.

hurz

7 years ago

E.g. We apply one milli ampere to a little bulb and measure its voltage while we heatup the bulb in an oven. The voltage we measure will increase or decrease depends in its filamente material. Thats what an DMM Ohmeter does and we can calibrate Ohm to grad celsius and have a temperatur meter.

kiani

7 years ago

Tried once to make a temperature sensor,,, every time there is a connection, or a socket used everything is messed up,

hurz

7 years ago

why?

kiani

7 years ago

Cause thr connections of thermocouple to wires and then wires to plug and socket and connection of that to circuit.. Each connection had to be of the same material, and seemed that each connection joint eas a thermocouple of its own. Teoerature reading drifting, all over and unstable.

hurz

7 years ago

Thats why thermicouples as pure sensor do have as wire the same material. Right, but connected a bulb to copper wires should work, cause its not a voltage you measure from a thermocouple, its the resistance you measure from a tungsten bulb. Dont mix thermoelectric with PTC behaviour of metal

kiani

7 years ago

Right,, thnx.

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