DIYEFI.org Forum

sim wrote:The car has driven an indicated 1984km since I installed the
FreeEMS ECU in mid September. <snip> It's safe to say that
the Snot Rocket has put at least two thousand kilometers on its
FreeEMS rig since installation.

Great to hear! :-)

The resulting report brought a few of my neighbours to their front doors.

ROFL!!! Nice work. The worst it'll do is shatter a weld on the exhaust or shake it loose. Unless you had a carby turbo, then it would insta-spool and maybe snap the shaft too :-)

The excellent logging was a major factor in the diagnosis.

<3

I'm very pleased to have a running car again, and I have no one
to blame but myself.

Though I feel it likely wasn't necessary, I appreciate you making this explicit, thank you!

A side effect of all this crap is I made an effort to mount my
board securely in the Tupperware container I have been using. Now
the board and all the outgoing cables are attached to the deck,
and there is no strain on the board solder connections.

Good side effect! :-)

I used an old cookie tin to make a bracket to hold my board up
off of the Tupperware lid.

LOL, I *LOVE* this true DIY stuff, it warms my heart! :-)

I'm getting close to having the ECU up and out of the passenger footwell.

Some advice, install a DB9 cable in there and put it somewhere accessible so that you don't have to open it to load code. Yes, I know about the switch, you can route those out to a hidden switch too. If you've installed the 100k pull downs on your outputs, then you can use that switch as a kill switch for the car ;-)

Look out turbo Citroen.

Did someone piss on your territory? LOL. What's the competition? The boost? Those things are pretty light ;-) One piece rods, too! :-)

http://puddle.ca/~sim/volvo/FreeEMS/ECU_Tupperware.jpg

Love this! :-) It inspired a new fb album with all the DIY ECUs in it :-)

On that note, congratulations to number eight and nine. What a
great start to the new year!

Absolutely, 2 cars in the first 3 days, wicked! :-)

I'm keen to get fueling up and running, especially after having to
troubleshoot EMS sync problems with a carb. Worst case on fuel for
my car is six months out. It could be sooner.

Great! :-) That french car should help us iron out some of the subtle things that are missing. He needs a tacho too, btw, so the priority on that just shot up a little.

Cheers all, and thanks again for the help troubleshooting Fred.

You're most welcome, Sim! :-)

Fred.

Look out turbo Citroen.

Did someone piss on your territory? LOL. What's the competition? The boost? Those things are pretty light One piece rods, too!

I was alluding to the board loose in the passenger footwell in
the Citroen video. I ran mine like that for months. I guess the
competition is "Most Hacky Rig" or something.

I was just making a joke, I think that old french car is awesome.

Ahh, I misunderstood by taking the wrong meaning of the two possible for "watch out citroen", the exclamation mark made me think you were implying you'd outperform him in some way. You meant "be careful with your board down there" woops :-)

Love the little relaisboard you made thx for shairing this,if i need a tach out i now know how to make 1
I also have a Arduino what i would like to test the circuist whit that i "solderd" together
(maybe we should have a free-Duino-stim and write some freeEMS code for it)
I do have a few questions for you
Can a relais handle this much shifting and and the high speeds it shifts at 6000 RPM?
Wasnt using a tach out on the dynamo not easyer?

Sim, you're welcome but your 82 ohm resistor scares me and makes me wet my pants. Please adjust the post to point out that that can not be driven directly with the CPU. 1k is required between a CPU pin and anything it's driving, or more. If you're using a 20mA capable line driver to push it, then sure, 82+transistor drop = likely OK, but if you mean to drive that with the TA, think again, quick!

Other than that, great post! I don't know if you looked at the code or not, but you could also point out that it's capable of running a 12 cylinder tach from your 24/1 setup or a 1 cylinder tach on a v12 engine, and anything else, limited only by the input pattern.

gixxer, what do you mean by "dynamo"? The relay will just be noisy if the rate of pulses is low enough, at higher speeds it wont move, but the coil will still fly back the same way.

Fred.

OK, I edited your post in an obvious way, change it to suit yourself, including wrapping :-)

One more thing! 4n25 has 70V CE break down. You could easily be getting more than that across the coil at switch off. Likely the opto will just fail if there is an issue, however you'll probably want to add a higher voltage transistor to do the dirty work for you. For driving ignition coils 400V is the norm, though I imagine this is lower, how much, not sure. If you have a nice scope that can take a high input voltage, find out for us? :-)

BTW, the slater is using a VB921 ignition driver for his coil, which, although overkill, certainly has the required parameters for this sort of task :-) Another option is a v protected autofet if you have any spares, they'll just cap the spike to 40 or 70 volts or so, which may still work ok?

Fred.

I mean the genarator (oops my wrong)
Older cars have a tacho output on the genarator (bosch)

Ahh and diesels, too :-) But usually on the alternator for those. I *think* Sim has a modern alternator on it, though. And the fact that the OEM system used the dizzy/coil probably meant that they didn't have such an output on the original charging system.

Fred wrote:Sim, you're welcome but your 82 ohm resistor scares me and makes me wet my pants. Please adjust the post to point out that that can not be driven directly with the CPU. 1k is required between a CPU pin and anything it's driving, or more. If you're using a 20mA capable line driver to push it, then sure, 82+transistor drop = likely OK, but if you mean to drive that with the TA, think again, quick!

Other than that, great post! I don't know if you looked at the code or not, but you could also point out that it's capable of running a 12 cylinder tach from your 24/1 setup or a 1 cylinder tach on a v12 engine, and anything else, limited only by the input pattern.

gixxer, what do you mean by "dynamo"? The relay will just be noisy if the rate of pulses is low enough, at higher speeds it wont move, but the coil will still fly back the same way.

Fred.

Please don't wet your pants Fred! It's not hooked up to the
FreeEMS board yet.

You did mention the need for a 1k resistor on the CPU pin, 82
ohms is what I calculated I needed based on the opto datasheet. I
wanted to just put up the schematic before asking you about it so
we could have something to look at.

One of the applications mentioned for the 4N25 was driving reed
relays, so presumably the thing can take a little flyback.

I did run the thing on my desk for a couple of days, nothing
burned out, mind I was using a pretty short pulse (1ms), so it
is possible the coil was not saturating completely?

My plan was to just drive the thing with a line driver, until you
told me you thought I could simply use a CPU pin. The Arduino was
able to drive it fine on a digital out pin, but if I burn out a
pin on the Arduino I will not be nearly as sad as if it happens
on the TA card.

I suppose I coould just add a 1k ohm and see if it still has
enough current to light up the opto.

Thanks for keeping a sharp eye on my bumblings Fred.

Fred wrote:Ahh and diesels, too But usually on the alternator for those. I *think* Sim has a modern alternator on it, though. And the fact that the OEM system used the dizzy/coil probably meant that they didn't have such an output on the original charging system.

Yep, proper alternator on my car.

I wonder what the diesel 240s used to drive the tach? Now I'm curious.