I have six 0-5V duty cycle signals coming out of an ECU that drive 6 direct injectors. However, I need to invert these signals and was considering the 4049 CMOS chip. Is this a good solution?
Also, I need to change the duty cycle signals to 0-12V. Any suggestions for this?
What current do you need?, simple open collector transistor drivers with pullups to 12V will both invert and change the signal to 12V - it's far easier to do this if you're inverting at the same time (as you are).
The circuit will be driving six 12ohm solenoids (fuel injectors).
I liked the idea that the single 4049 CMOS chip ($0.30) has 6 drivers which is perfect for this 6 cylinder engine. Otherwise I'd have to run 6 transistors.
A CMOS logic chip can't feed a solenoid, it has no where near the capacity.
Check the relay driver circuit on one of my tutorial pages at
This inverts, and drives the solenoid direct, assuming it's switched in the negative lead. You would need to use transistors with enough gain, and current capacity.
Sorry, let me clarify I wleft some vital information out.
This signal will not be driving the fuel injector directly, rather it will be going through a controller which is about 62ohms and inductive than the controller will be driving the 12ohm injector.
Sorry, let me clarify I wleft some vital information out.
This signal will not be driving the fuel injector directly, rather it will be going through a controller which is about 62ohms and inductive than the controller will be driving the 12ohm injector.
That should be a lot better, but I would keep an eye on how warm the chip gets - obviously the current is only pulsed, so it's not current all the time.
But does it need to source or sink current?, the ULN will only sink current.
Think of a switch and a bulb - you can connect the bulb to 12V and the switch down to chassis, this is SINKING current, or you could connect the bulb to chassis and the switch to 12V, this is SOURCING current.