West-se

Im waiting for my kit to arrive and need to get the parts together to build the 2nd VR circuit in the proto area can anyone give me the list of what I need and a schematic, I've looked at the dual VR circuit parts list and layout but if someone could provide a single circuit schematic and parts list (digikey) that would be great, I did notice that 1 of the caps, is no longer available from digikey the .01 uF i think it was.

muythaibxr

for the .01 cap, I'll take a look and see which one I ordered the last time I bought them as I do remember the one that other people are using is no longer available.

There is a schematic for what is needed here:



You'll want to change the 50k resistor to an 82k resistor, and the .001 cap to a .01 cap.

Ken

West-se

thx muythaibxr, I was just reading on the ignition thread over @ ms trying to use the stock coils with the CAS. Im stuck right now as to how to proceed with my build since I've got a T2 which im intending to run around 12 psi and make around 350 rwhp. I'm not really sure which way to go.... any ideas ?

muythaibxr

I'm not sure what you're asking, all the instructions for hooking up to stock ignitors/coils and using the CAS are in the FAQ.

Do you have a specific question that's confusing you?

West-se

diregard I just realized that the thread i was reading had JUST been dug up from over a year ago, my bad. Thanks for the schematic

sjd

I'm going to be doing the same thing. That diagram is great but is there an actual picture or parts list anywhere?

West-se

1 lm1815 chips: LM1815N-ND
1 18k resistors: 18KQBK-ND
1 1M resistors: 1.0MQBK-ND
1 82k resistor: 82KQBK-ND
1 4.7k resistors: 4.7KQBK-ND
1 .33 uF capacitors: 493-1138-ND
1 .01 uF capacitors: 399-1868-1-ND
1 330 pF capacitors: 399-1920-ND

sjd

Excellent thanks.

The Griffin

Here's a thread with some pics to give you some idea how it looks completed.
https://www.rx7club.com/megasquirt-forum-153/pictures-newbies-493393/

renns

West-se,

If you are not an electronics hobbyist, I'd recommend you skip the 2nd trigger method of setup, and grind off opposing teeth on the 24-tooth wheel instead. This allows you to configure the wheel trigger setup as the equivalent of a crank-mounted 12-1 wheel. You'll loose nothing from a MegaSquirt functionality standpoint, and avoid the fun involved in setting up the LM1815 circuit.

West-se

I hear ya Renns im building my kit so I've got no issues with the 2nd circuit

mycarisolderthanme

So renns, you give me the impression that the 2nd circuit will be tougher to build. Is that because you have to run your own wires? What makes this circuit harder to build than the rest of the kit, besides the lack of explicit directions from megasquirt?

West-se

this list is missing the .1 uF cap

.1uF capacitor: 399-1874-1-ND

muythaibxr

It's not totally necessary... it looks like it's just there to get rid of noise on the +5v input, but you also probably don't have to worry about that when running it from +5v inside the MS.

renns

There's nothing particularly difficult about building the 2nd circuit, but whether it's via error*'s daughterboard, or in the proto area, it's still one additional circuit that MUST work properly for your MS to function. There are potential issues with the circuit itself, and also with cross-talk between the two VR sensor signals. These can be overcome during the course of the install if the builder has the required electronics assembly and trouble-shooting skills. For most automotive hobbyists, knocking a couple teeth off a VR wheel is trivial, while building and interfacing electronics circuits may not be.

Here's a list of common MS configurations, from simplest to most complex. (Dizzy=Distributor ignition, 12A/GSL-SE 13B)

1.) Fuel-only with Dizzy ignition, tach signal from coil.
2.) Fuel-only on FC, with stock FC ecu firing plugs, tach signal from coil.
3.) Fuel-only with Dizzy ignition, tach signal decoded from modified CAS (1 VR circuit)
4.) Fuel-only with Dizzy ignition, tach signal from decoded stock CAS (2 VR circuits)
5.) Fuel and spark, dizzy locked, MS provides leading spark only
6.) Fuel and spark, modified CAS (1 VR circuit)
7.) Fuel and spark, stock CAS, V3.0 board, 2nd VR in proto area. (2 VR circuits)
8.) Fuel and spark, stock CAS, V3.0 board, error*'s daughterboard. (2 VR circuits)

This list assumes you have an efi-capable vehicle (ie not converting an old carb'd FB). The higher up the list you start, the better your chances of success, due to reduced complexity. That's my $0.02.

muythaibxr

I'd say it depends on how well you follow instructions, and how good you are at various wiring tasks.

For example, I started out as a complete newbie about a year ago using an HEI module to run leading ignition... 3 months later, I had leading only running on the wheel decoder, and 3 more months later, I fixed trailing and had it running too. I started out with no electronics skills, and learned the assembly language as I went... (with some encouragement from you if I remember correctly renns)

If I can do it, anyone can.... I think it's just a matter of being patient, doing a lot of reading, and learning as you go... I think a lot of the problem is that people rush into it trying to get it working as quickly as possible...

So I agree with your list on the order of difficulty (although I'd switch 7 and 8), but I think that at worst, going from 1 through 8 should be a progression, starting where the user feels comfortable, and moving up. I felt comfortable with wiring and such, so I went from something similar to 6, straight to 8. (I only did it because the 2nd trigger wheel decoder didn't exist yet). It's all what the user feels comfortable with if he is doing it himself.

mycarisolderthanme

Thanks for the reply renns and muythai. I definitely see your point that building another circuit could just cause problems for me, but I figure if I can manage to build and operate the megasquirt itself, one more circuit shouldn't be too bad. I think I might just search for a spare CAS and modify that so I can switch back to my stock setup if needed. Again, thanks for the assistance.

West-se

mythaibxr: what asm have you worked on with MS ? I have asm experience and would love to start getting into some of the code. All me gear is on the way, I bought an innovate lc-1 +xd-1 wb02 and think I will get my MS working in my cars lightly modified state (stock turbo) and then once I have some experience with megatune and get fuel maps where I'd like them, then I'll start on adding my big turbo, FMIC and new injectors. I am very excited to get started.

renns

Ken,

You made amazing progress in a short period of time, but that's a feat that the average rx-7 enthusiast would be hard-pressed to duplicate. The average joe just wants his car to run, and doesn't really care much about efi controller design. The fabrication, modification, and debugging steps MS requires will be seen as a PITA, rather than a learning opportunity. That's the real difference...you took the opportunity to learn, and ran with it. Some will not have the ability and/or interest in repeating those steps, but may buy an MS on price alone. Even with the excellent support you are providing here, it may not be enough in some cases.

West-SE, if you have any asm experience, grab the source code and take a look. It's well documented in most areas, so you should be able to follow along. Then if you dream up some whacky feature (flash your neon runners in time with rpm or some such thing), you can make the changes yourself. Chances are there'll be enough features in the -extra code to chew on for quite a while.

muythaibxr

renns: point taken... I guess I just thought that my progress was average.

West-SE: I fixed trailing ignition after james over on msefi.com wrote the initial code. The initial code had a bug where at less than around 2 degrees of split, there'd be misses on trailing. After I fixed that, there was another bug where you'd have misses on quick accelerations at low rpms, so I fixed that... I added the idle advance feature because I liked how it made driving around in traffic jams almost at idle smoother... And I added the staged injection transition code that allows the staged injection transition to occur over a user-definable number of ignition events (gets rid of the "3800 rpm stutter"), and I added a second parameter for staging (kPa only) because below a certain kPa, staging isn't needed when used with rpm based staging. I did all these things because I had little things that I wanted to be able to tune better.

mycarisolderthanme

We need you to get into a turbo FC and find little things like you want to tune in that scenario. =)

West-se

Well im really looking forward to getting my hands dirty. I've now got a copy of the source, I'll review the disassembly and get familar with the opcode library. I will be running this on my TII within a few weeks. Im sure I will have some questions.