Wrong Capacitor
 

Ok, so i know i'm asking a lot of questions but i wanna get this thing up and running.

Can someone chime in on this and tell me if DIY sent me the right capacitor. On the online directions, C31 calls for a .1 micro farad capacitor, but in the DIY kit C31 is labeled as a .001 micro farad capacitor. Which one do I follow?

hmm... it could be they mislabeled the kit.

i had one of my components mislabeled as well, one of the Q transistors with the small three prongs on it. i had to examine it closely to find out which was what. i did receive all the correct components though, just one was mislabeled

Not a mistake so much as an update. There was a bill of materials change recently. Bowling & Grippo have used several different values for C31. Sometimes our kits are ahead of the documentation, and sometimes we have kits ship out with a slightly older bill of materials setup. But if you use all the parts from a given kit together, they'll work. If you want the parts for a particular version, let me know.

Great!! Now I can just finish up the MS and play!! I just wanted to make sure i'm not putting in the wrong parts. Don't really want to just make it and then have to desolder it.

Thanks guys!! Now i'm done and ready to plug in and tune.:bigtu:

Megasquirt Kit Issue? Or Documentation
 

This is from an old post (2007) but I am still having a similiar problem with my kit. The latest MegaManual and BOM from Digikey does not match what I received in my kit. Anyone experiencing the same issue? Which is correct?

Can you give us a specific reference?

The MegaManual asks for Capacitor C15 pn 399-4202-ND 0.001uF 50v, but the kit has
C15 as pn 399-2017-ND .001uf 100v Cap which is 100v. And it seems the issue with C31 is still not correct.

I did not expect to have to deal with this when I purchased the kit. The online manual should match or a bulletin should be included with the kit when something changes. Learning this shit already gives me a headache without having to spend time on these issues.

its the same thing, it's just rated to handle more voltage.

Thanks, Brain

I never install C31 so it doesn't bother me whatever it's rated :P It's part of the VR circuit which you wont be using on a typical miata install.

So using a cap rated to a higher voltage is ok practice? I had to source one recently to replace a 0.1uf 50v cap and could only find a 0.1uf 100v cap, that will be ok then>?

Thanks

Yes. The voltage rating on a capacitor tells you what the maximum voltage you can apply to the capacitor is without causing it to fail. With ceramic caps in particular, it is almost always permissible to substitute a part with a higher voltage rating.

The same goes for diodes. Take the common 1N4001, for instance. It is rated to pass 1A continuous forward current, while causing a maximum of 1V forward drop. It is rated to withstand a maximum of 50V peak reverse voltage. There are six other common diodes in this family, the 1N4002, 1N4003, ..., 1N4007. The only difference between these is that the 4002 is rated for 100V peak reverse, the 4003 for 200V peak reverse, ..., and the 4007 for 1000V peak reverse. So it is always OK to substitute a 1N4002, for instance, in a place where a 1N4001 is called for.

Ditto resistor with their wattage ratings. The only difference between a 1kΩ 1/8 watt resistor and a 1kΩ 1/4 watt resistor (apart from physical size) is that the latter is capable of surviving twice as much power without bursting into flames. So you can always substitute a higher wattage resistor for a lower wattage one, assuming the resistance valve and tolerance are respected.

Similar substitutions apply to transistors, FETs, and even a lot of IC classes (such as op-amps) although the rules are more complicated.

Very informative ^^^ thanks alot :)