micro processing ??

[twizzle]

hi guys

I am new to this so please feel free to spoke dumbed down talk for me.

I and looking to run 2 sets of LED lights which will light, each set at separate times, dependant on the varying voltage to a 7.4V load.

1st set of lights are to energise on a reduction of Voltage to maybe below 4V.
the 2nd are to energise on reversal of the voltage.

The reversal of voltage is I think a simple matter of putting a singe direction diode on the load terminals that when voltage is going forward the diode will stop current flowing, but when reversed the current will flow through LEDs.

the LEDs that are to be turning on when voltage is below 4V, will this have to be by means of a micro processor, or is it possible to do it using a semi conductor and a potentiometer

any help would be great fully received

 

[ultrafire3]

Try this!

 

[twizzle]

thanks but I think all that may be a bit over my head.
is there a simple way of may be at under 4V 1 LED will light and above 4V. some thing like a 2 way relay with a resistor in line with the coil, at voltages under 4V there will not be enough voltage to operate coil, so the first LED will be lit via the relay....when the voltage rises there will be enough voltage to operate the relay and it will disconnect the first LED and switch to the second LED.
when the voltage drops again the relay will drop back to it original point.
only I was hoping the do this electronically as space is limited, there is a lot of vibration and I want to keep down the current drain of a circuit

 

[Fish4Fun]

Look up "comparators". http://www.ebay.com/itm/2-x-LM311-L...670?pt=LH_DefaultDomain_0&hash=item3a6846ffee

You can configure them to "trip" at virtually any voltage.

Fish

 

[twizzle]

Look up "comparators". http://www.ebay.com/itm/2-x-LM311-L...670?pt=LH_DefaultDomain_0&hash=item3a6846ffee

You can configure them to "trip" at virtually any voltage.

Fish

will I need additional programmer to set the trip voltage

 

[BobK]

No, just a voltage divider, and possibly a voltage reference if you are not running off a regulated supply or need more accuracy than the supply voltage.

Basically, if you put any voltage on the - input of the comparator, then the compartor will turn on when the + input exceeds that voltage. Or you can reverse + and - to get i to turn on when the voltage input is less than the reference voltage.

Bob