What size flyback diodes?
 

Hi,

I run a Speeduino with a home-made conversion board from Speeduino to NB VVT harnas plug. All is working well, but I didn't design flyback diodes into the conversion board. So, I soldered some 1N5408 diodes on as they were the most chunky ones I had laying around at the time. In the meantime, I soldered on lost more mods, and now it is time for a revision of the board. But do I really need those huge 1N5408 (3A) diodes, can I get away with DL4007 (1A), or even with faster Schotkys like the 1N4448? I'm trying to use as much SMD components readily stocked by JCL as much as I can. I don't really know (or can find googling) the currents for the VVT and IAC, for instance.

Cheers,

Hugo

You're tooling a PCB for this project? I don't have an answer for you regarding the current for the VVT and IAC solenoids, but if 3A works then you could just use something like SDT3A45SA-13, which is a 3A schottky diode. They're still like $0.50 or less so unless space is at a huge premium on your PCB it's worth it. Even then it's just a DO214 package so they're not very large at 2.3 x 4mm. You also would have the advantage of DO214 being one of the most common diode packages so you could easily swap the diode out for something else if the part ends up not being suitable. The 1N4448 does not seem to be a schottky diode.

I wasn't able to find an electronics distributor by the name of JCL, but Digikey and Farnell both seem to have that part and have distribution in the Netherlands, but anything similar should do just fine.
https://www.digikey.nl/en/products/d...zQWgEYUQBdAXyA

I'm fairly certain I used a 1n4007 diode on my NB1 IAC valve FWIW. I've had no issues with that for ~6 months now.

Thanks, both, for your input.

JLC is the PCB maker I use, they stock a lot of SMD parts so I can order the PCB with most parts already soldered in place. And they have SK310A! Good option, I didn't consider Schottky.

Cheers,

Hugo

Good idea and good luck.