# Excessive power consumption

Discussion in 'The Projects Forum' started by kelly.jr., Mar 5, 2015.

1. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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Hi, I am new to electronics. I've been working on this Pulsating LED Project of mine. I use Proteus to design the circuit. I've been wondering what is making the circuit consuming so much power ( it's +63.0 Kw). Thanks for your help.

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2. ### kdcouture200 Member

May 22, 2010
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I would guess that the reason you are getting a reading of 63.0 KW is because the power meter is in a closed loop with the battery only and not the rest of your circuit. so with the resistance of the meter being so small a large current is going to form causing a large power reading.

3. ### MrChips Moderator

Oct 2, 2009
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63kW

That's about 50 times what my whole house consumes.

That is because your wattmeter is shorting the battery.

Your circuit takes about 100mA @ 14V = 1.4W

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4. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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I just re check my circuit on proteus. I think I wire the Wattmeter just right.

5. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
17
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Then why do the Ammeter on the VCC read +MAX?

6. ### R!f@@ AAC Fanatic!

Apr 2, 2009
9,618
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Don't think so. Try Again.

7. ### MikeML AAC Fanatic!

Oct 2, 2009
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Besides, that is a very complicated 555 multivibrator circuit. The LED driving can be greatly simplified. The 555 can drive ~200mA with no buffering...

Here is a LTSpice sim of the running circuit, greatly simplified. Note that LTSpice shows us all we need to know (node voltages, branch currents, power dissipated in each element) without having to wire in the stupid little instruments into the schematic, which make it much less readable...

I show the voltage at the timing network V(c1) red trace V.
I show the battery current I(V2) green trace mA.
I show the power delivered by the battery violet trace W.

All of those are added to the plot just by placing the mouse cursor over the component on the schematic after the sim is run.

Last edited: Mar 5, 2015
8. ### alfacliff Well-Known Member

Dec 13, 2013
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your 555 is drawing max current, either it is bad or the connections to it are shorted.

9. ### kdcouture200 Member

May 22, 2010
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And your Watt meter is connected incorrectly.

10. ### alfacliff Well-Known Member

Dec 13, 2013
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becasue if the 555 is hsorted, the cureent will be max. and the voltmeter will read max because it isnt real, with the limitations on the power supply.

11. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
17
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I am new to electronics and the simulator. I am currently using proteus. I will give LTSpice a try.

Your circuit doesn't make the Leds fade in fade out (breathing). I want the graph look like this.

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12. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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I think there's something wrong with proteus on my PC. Because when I simulate MikeML circuit, I still get the same result from the Ammeter (which reads MAX)

13. ### alfacliff Well-Known Member

Dec 13, 2013
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since the 555 timer and a 4.7k resistor are the only things connected to the 14 volt supply, what is the scaling of the ampmeter? neither should draw very much current. how many amps is the meter rated in ypur program?

14. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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The scaling (Display Range) is in Amps. When I use probe It reads 9000. see image below

15. ### MikeML AAC Fanatic!

Oct 2, 2009
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I think the Proteus 555 model is at fault (model error).

I now understand about the "breathing"; I missed that.

A minor question about the simplified circuit: Why do place D10 there? It is not needed, and only "wastes" 0.6V that would otherwise contribute to LED current. Note that You now correctly have a current-limiting resistor in series with each group of LEDs.

16. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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I use the diode D10 to prevent current from capacitor C3 flowing towards the Output (Q). I try to made the leds fade in fade out but the graph is still too steep.

Last edited: Mar 6, 2015
17. ### alfacliff Well-Known Member

Dec 13, 2013
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is the battery the correct polarity?

18. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
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Can I get the graph to look like this without using a transistor?

19. ### kelly.jr. Thread Starter New Member

Mar 5, 2015
17
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what do you mean by "the correct polarity"?

20. ### alfacliff Well-Known Member

Dec 13, 2013
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positive and negative connected wher they are supposed to be.