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Need to simulate different wattages

  1. Mar 16, 2012 #1
    Hi all,

    i have an embedded board which is capable of driving loads of different wattage(75W, 21W lamps etc) at 24V using some driver Integrated Circuits. The embedded board is programmed in such a way that the output is cutoff (there is no 24V output) when the loads are not connected. Now i want to simulate the different wattage using a hardware circuit without actually connecting the loads since there are around 30 outputs. I am actually trying to get 24V output and display it on the personal computer that the particular load is ON based on some input switch condition but i am not getting 24V now as no load is connected. Could somebody give me some idea how to proceed. please let me know if i am not clear.

    Thanks and regards,
  2. jcsd
  3. Mar 16, 2012 #2


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    Staff: Mentor

    You want all outputs loaded simultaneously? Something like a resistor from each output to ground? They would have to be power resistors, and the cheapest are usually light bulbs. What is the minimum load that should be recognized? You could try 5 watt power resistors, maybe even overload them 100% for 5 or 6 seconds. A 100 Ohms resistor would dissipate about 5 watts of power. The resistors will get hot.
  4. Mar 16, 2012 #3


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    Science Advisor
    Gold Member

    Not sure what you mean by this. It seems contradictive to me.
  5. Mar 16, 2012 #4
    sorry i was not very clear in my explanation. now i have attached a picture.
    1. The embedded board is having a software program running in it and the purpose of the board is to switch on loads like lamps of different wattages(75w, 21w etc) at 24V in the field.
    2. My aim is to validate the software that is to verify whether the program is properly switching on the loads when the corresponding switch is switched ON on the bench before actually going into the field.
    3.For that i have designed an interface board which would simulate the switches by giving 24V/0V with the control from the personal computer and read back the outputs from the embedded board into the interface board. If 24V is coming into the interface board i assume the load is switched ON and the same would be displayed on the PC.
    4. The problem now is the software in the embedded board has been written in such a way that it would give 24V to the load when a switch is ON but in case no current is drawn from the particular load then it would immediately make the voltage to some 5V. My problem is that since the interface board is not drawing any current the embedded board software would immediately cutoff 24V. my interface board cannot withstand more current so i want to introduce one more interface circuit which would draw different and required currents so that it gives out 24v which i can read through the interface circuit and display on the personal computer(All the loads may not be ON at the same time).

    Hope it is clear.
    thanks and regards,

    Attached Files:

  6. Mar 18, 2012 #5


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    Staff: Mentor

    Sorry satya77, if anything it is now less clear. qyps9.gif

    Apparently a resistive load isn't going to be a solution UDocr.gif
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