Hi to all. Please i'm looking for a valid solutions. I have a negative signal and I would like to convert it to a positive one. I need the positive signal to be faithful to the (original) negative signal in terms of both frequency and duty cycle. Furthermore, they need to be synchronized, meaning when the negative signal is low, the positive signal is high, and vice versa.

 

What is the load on the signal? In other words, how much voltage and current are required of the output. What is the frequency and voltage of the input?

 

hi M,
Voltages, frequencies, wave forms????
E

 

Duty cycle you say? So it is a digital signal then?
If so, what you really meant is that you require to INVERT the signal?

 

I have a car ignition system that originally grounds a coil and then disconnects it to create a spark. Now, I've obtained a wiring diagram from an old ECU (which I've tested and works well) that needs to apply a positive voltage to the gate of an N-channel MOSFET and then disconnect it to generate the spark.

The situation is very similar to this post https://forum.allaboutcircuits.com/...to-4-postitive-signals-on-1-pcb.204625/page-2

need to fit something between ecu and R2

 

OK, based on the description that is a logic inverter, not a polarity changer.

 

Correct

 

OK, so you're driving an ignition coil based on a logic signal. You need logic-low to turn on current to the coil and logic-high to turn off that current.

Correct?

What is the logic-high voltage? Is it full battery voltage?

 

@wayneh Full battery Voltage

 

need to fit something between ecu and R2

 

As above, a single transistor can be used to invert the signal.

I believe using a single P-channel MOSFET could also do it. That's why I asked about the logic-high voltage - it has to be as high as the battery voltage to shut off the P transistor. Logic-high equals zero current.

 

Ok but now the ECU short to GND to make spark. I think with @sghioto solution it will spark but with different timing.

 

Ok but now the ECU short to GND to make spark.