Updated Q5 and Q6 as IRLD024PBF is discontinued

[cmdrscotty]

IRLD024PBF has been discontinued and soon be no longer available. I've updated the PCB Q5 and Q6 to use IRL510PBF-BE3 TO-220-3 packages as they are more readily available and updated the board revision to E as this is an alteration to what needs to be used (only two parts different Q5 and Q6, all others remain the same)

[74HC14]

The 100V breakdown voltage of that transistor seems a little high, it seems like typical values are closer to 60V, and the original transistor was more like 35V. According to this document, the selection of the clamping or "flyback" voltage is what sets the speed of magnetic field collapse and hence the closing speed of the pintle. Importantly:

"If the pintle is allowed to close too fast the pintle and seat will become pounded out and will begin to leak fuel. With a fast closing rate the pintle can also bounce causing extra fuel to be delivered to the engine. This extra fuel cannot be controlled accurately so the engineer must adjust the energy held within the flyback voltage to accurately control the closing rate of the injector. This is done by using a zener diode across the PCM driver..."

While I lack the wisdom to know if 100V would be enough to cause problems in most or even any engines, I suspect across the variety of injection types (manifold, port, direct, even diesel) it would be worthwhile for builders to have the option to more easily adjust this value. Hence I suggest through-hole zener diode footprints would be a more valuable addition to the circuit.

There are a few methods one might employ to attempt to set this pintle closing speed in software, though they'd probably require additional hardware.