eem2am
Joined: 22 Jun 2008
Posts: 751
Helped: 13
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 02 Jul 2009 17:36 how to stop input supply current ever going to zero? |
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hello,
the input supply current into the following circuit from the ~13V source (V1) must never go to zero.
if it goes to zero then a fault detector at the source thinks that the circuitry has failed. -we don't want this to happen.
Thing is, when there is a transient in the supply from 14V to 12 V , the circuits supply current does indeed go to zero for a few microseconds........this is due to the EMC filter oscillating.
How can we stop this?
That is, how can we stop the supply current from V1 going through zero when there is a transient in V1?
Here is an example of a 14v to 12v transient.............
Here shows the input current which does indeed go to zero for a few microseconds when the transient occurs...........
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FYI, we are in Nebraska doing some LED light stuff off car batteries.
there are many led lights and they are all fed from the same supply, -only when a different main light goes out do we want failure indication, therefore the above circuit is rigged up to actually draw current through the resistor in the npn's collector when this lamp fails.............that way the sensed current from the supply will remain high..........and not give a main lamp failure...........until the main lamp itself fails!
anyway, how do we stop the current going to zero...?
or is this just a feature of the front and CLC filter that it resonates when a supply step occurs?
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