New Type Relay Board

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masp
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New Type Relay Board

Post by masp »

Hello,

I am in process to develop new type of relay board for my self, and maybe for others if there is interest.
idea is simple, all in one, all wires from one place, all relays, fuses in one board, S1-S5 is the same outputs as on original B&G relay board.
I tried to keep high current output traces short, fat, double sided and away from signal inputs.
My addons:

additional 6 +12V fused outputs for single ignition coil or coilpack, wideband controller, etc., from fuel pump relay
one +12v fused output when ignition on (hall sensors, or anything that need 12v with ignition on)
Additional relay, with one 12V fused output, that can be switched on via programmable outputs, for example electric fan etc.
db37 3-6 pin outputs to terminals
fatter trace sizes
multi fuse holder for different type of fuses
atx connector for input.

pcb size is 100x100 mm

any questions/suggestions welcome!
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Last edited by masp on Wed Nov 29, 2017 10:30 am, edited 1 time in total.
DaveEFI
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Re: New Type Relay Board

Post by DaveEFI »

My view is I don't want any additional connections unless essential. So if I were designing one, I'd make it handle the power side only, with all sensors going direct to the MS DB37. And the same with the main MS grounds.
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gtmdriver
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Re: New Type Relay Board

Post by gtmdriver »

I am driving a 4 cylinder wasted spark Ford coil pack directly from the MegaSquirt 2 v3 rather than using the Ford EDIS unit. The standard relay board wiring only provides one high current ignition output and I needed a second one.

I solved the problem by wiring the VR sensor directly to the MS unit to free up a terminal and then wiring pin 6 on the MS D37 connector to pin 24 on the relay board D37 connector so that terminal 15 on the relay board connector strip became the second high current ignition output but it would have been easier if there had been a dedicated second ignition output on the relay board connector.



Image



That's my suggestion. Additional high current ignition driver outputs on the relay board.
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Re: New Type Relay Board

Post by masp »

Pins S1-S4 are outputs from megasquirt pins 3-6, traces to S3 and S4 are 2.5 mm wide from one and 3mm wide from second pcb sides, if i am correct that wil be enaugh for 8.3 amps of current, and i think can be used as high current ignition outputs. Pin S5 is pin from megasquirt pin 36, trace width is 3mm from both pcb sides. Ground to megasquirt is 3mm wide from both pcb sides. I preffer to use IGBTs outside megasquirt case.
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Re: New Type Relay Board

Post by DaveEFI »

The other thing is having a plug to plug connector between MS and the relay board means the distance between the two is restricted to available loom lengths. Unless you make up your own. But then you have easy to wire screw terminals for all the other connections.
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Re: New Type Relay Board

Post by masp »

So i made my first prototype, but with old design, it has no additional sensor ground, but with short cable to ms, i think it will have no problems, so for now some testing in process..


Here is assembled pcb. https://ibb.co/eTDCcw
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Re: New Type Relay Board

Post by ChevelleFan »

Nice work!

I know the relay board gets a bad rap around here and I've always wondered why someone never updated the old one. I use one in my Chevelle and it has worked great. You should consider adding enough terminal capacity to accommodate wires from the DB15 on the 3.57 boards.

-Dave
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masp
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Re: New Type Relay Board

Post by masp »

so for now i have two versions of drawings , one with db37 connector, other with atx connector.
advantage of db37 version is that it can be plugged straight in to megasquirt without any cables, but disadvantage is thinner one sided traces. Megasquirt and relay board need to be in the same level, screwed to panel. If there is something bad about db37 version that i am missing, please tell me, so will not waste time on that. This booth versions is with cheaper fuse holders.

Image
Image
T3Bunny
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Re: New Type Relay Board

Post by T3Bunny »

I have installed many of the relay boards and they do make for a much easier setup. With many installed, I have seen two repeated failure points. The DB37 and the screw terminals. My solution has been to simply solder directly to the pins of the screw terminals, but the DB-37 has still been an issue. And not easy to accomplish this.

If I were designing a relay board, I would have these features.

1) The plug deserves the most thought here. I might still use a DB-37 like the MS one, but also have through-holes to solder the wires directly. I wouldn't bother with other plug options. Or save money and JUST use through-holes for this. Connectors are usually the biggest expense for stuff like this, and also the biggest pain in an install to solder up. Eliminate as many connection points as you can, and you add reliability. In the 15yrs I have run MS daily on my personal vehicles (and I have only built and used two units for myself) the only weak point of my installs has been the DB-37 connector on the MS. EVERY SINGLE FAILURE I have had (ms related) has been traced back to a failed connector. Another reason to just use via holes goes back to future expandability. Right now there are no easily used solutions with the MS3 expansion boards. Using a new relay board without a plug would allow these to easily be soldered in.

2) Retain the screw terminals. They make for quick initial setup and simple future testing. But again, add in through-hole solder points so wires can be permanently fixed. Sure, you can just not install the screw terminals, but they do make initial setup SO MUCH easier.
3) Have at least one spare relay. Two or three would be even better. (I see yours has one additional one.)
4) An unpopulated spot for either IAC or boost controller circuit. To make this viable you need to...
5) Have the extra pins available going to jumper holes.
6) Separate the injector traces. This adds minor complexity, but it also allows this relay board to be used with MS3 and individual injector drivers.

I would NOT cheap out on the fuse blocks. Use the better ones. While cost is always a factor, reliability is more important then what might add up to only a few dollars saved. And Mini ATX fuse holders work well. No reason to take up the real estate with the bigger fuses. I have never seen an issue with the fuse holders used with the MS-Relay box. But one possible problem I see with yours is...

7) Space the fuses out a little bit. There needs to be enough room between them to grab with needle nose pliers or a fuse puller.

I love the compact size of your prototype. I would be willing to lose some of that for the extra via holes and a second spare relay. And more fuse space.

8) Even better than just mounting holes, would be sized the same as a MS ecu case. The way the MS Relaybox is mounted is hard to beat for a clean and fast install.

I don't know how I feel about NOT running sensors through the relay board... One of the biggest advantages to using a relay box with everything running through it, is the ability to sort out install issues during initial setup. Also, it makes utilizing a stock harness much easier, or allows you to build a proper custom harness from the furthest point inward.

I think just a "power board" is an awesome idea! But ONLY if it is accompanied by a second sensor board. That might be the key to a low-cost solution that satisfies many more users. The sensor section does need separate individual sensor grounds and also room for additional injector channels. Probably the same for ignition drivers. A better approach might simply be a larger board with the power and sensor sections well separated.

The MS-Relay box is well proven with a few weaknesses, but it has another MAJOR disadvantage to using it. It has very limited future expandability.
With the dozens of installs I have done a relay board easily cut a day or more off the average job. The only reason I didn't use them for EVERY install was that lack of configurability. The small additional parts cost was never a factor since the labor savings easily paid it back. In fact we had one bored Friday night where we decided we would do a full MS conversion on an old Rabbit that was still running mechanical fuel injection. The challenge was to do it over that weekend. We managed to pull it off and had the old CIS system out, new fuel system in, a harness built, and everything wired up and running by Sunday night. The only way we managed to pull it off so quickly was by using the MS-Relaybox.

I am VERY interested in this project! But as it sits it is simply a different version of the original MS Relaybox. If at a minimum you separate out the injector drivers and then hopefully add in a few or all of the features above, then it becomes a relay box that can be used with MS3. Right now there is nothing easily usable for a MS3 install.

I spent the whole day beating on my car today. A blown fuse killed my radiator fan and required me pulling my whole lower dash to get to it. After pulling the lower dash, I realized how badly I need to do a major overhaul and wiring clean up. I actually came to the forum just to look and see if there were any new relayboard options out there that would help with this, I will be watching this space!!! In fact, please PM me if you have another prototype board available!
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DaveEFI
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Re: New Type Relay Board

Post by DaveEFI »

My feeling is that no matter how you do it, if you are using plug in relays, using a PCB for those adds another connector, over wiring directly to those. Good quality spade connectors are one of be best around, if crimped to the wire correctly.
I can see a relay board would speed up a pro installation where time is money, but a well designed and made loom is the basis of any reliable conversion, so don't see the point for DIY.
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T3Bunny
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Re: New Type Relay Board

Post by T3Bunny »

DaveEFI wrote:...
I can see a relay board would speed up a pro installation where time is money, but a well designed and made loom is the basis of any reliable conversion, so don't see the point for DIY.
Most of us who have been here a while, yes. But in the installs I have done over the years I would say that more than half of them already tried to do it themselves. And failed so badly most of the time I had to start from scratch. I think for the average DIY-ER the simplicity added makes sense. As long as it is setup to facilitate proper wiring.

Proper “point to point” wiring is beyond the average youngster (be it age or just electrical experience) to pull off well on the first attempt.
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masp
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Re: New Type Relay Board

Post by masp »

So i developed test version without need of relay board cable, just plug straight to ms2. I replaced main relay with mosfet to save a space and cost. it gives power to ms and 12v output only. One relay is switched by fuel pump output, and another is spare for anything, can be triggered by 12v and output is fused high current 12v. High current traces is without solder mask (Main ground, injectors, 3-6, 30, 36 pins) to be able solder additional wire easy over them. Tested only on bench for now. This is poor man's version :)
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T3Bunny
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Re: New Type Relay Board

Post by T3Bunny »

masp, I really wish I knew CAD and could design my own board like you have done here! If you (or anyone else) is interested, I would actually pay to have a relay board designed for me. I just got materials to redo my whole harness, so I actually am in need (well want I guess) of something like this soon to clean up my install.
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DaveEFI
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Re: New Type Relay Board

Post by DaveEFI »

You don't need CAD as such for something as simple as a relay board. Any vector drawing prog can be used. And skill, of course. Can be fun if you like doing such things. You can also produce simple PCBs yourself at home quite cheaply. Google will give you the method. There are also firms which will make one off PCBs for you - but you'd need a vector prog that produces the correct file types for them.
The first PCB I made at home had the tracks drawn by hand. Long before I had a computer. :D
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Re: New Type Relay Board

Post by T3Bunny »

Well, I am not versed in the vector drawing programs either. I have also cooked up a couple boards in the past by hand many years ago. They didn't turn out well... So while I might be able to edit a file that is close to what I needed, I am not sure it would look pretty or be well enough thought out. I lack all the skills required, other than knowing what I want/need in the final outcome.

The way I approach something like this is "What is it worth to me for a better solution?" I would almost spend the money on a standard MS relay box, but I know that for an MS3 setup it requires additional work and isn't ideal. Also isn't ideal the way I have my system already wired. I can start over from scratch on my power grid and rewire it in a few hours with stuff I already have on hand. A whole new harness, even with my additional mods, should only put the car down a week or two.

But spending a little more to get a much better solution in my hands that meets at least all the most critical needs and knocks the install down in simplicity to a day or so, that is worth the effort to pay for. I have to balance out what my time is worth versus paying somebody to do it better...
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