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LQFP112 - Up with the play
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This is the comments thread for my build thread, please post comments here.

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Thu Jul 28, 2011 5:35 am
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Quote:
21:00 < simis> So, I swung by one of the local electronics bits suppliers yesterday morning. Shiny and nice but more expensive than the hole-in-the-wall dealer on Main st.
21:01 < simis> They only had the inverting version of 74HC[367,368] in stock, so I picked up two SN74HC241N chips for $0.88 instead.
21:02 < simis> It occurs to me that line drivers will suit not only the LS1 coils, but also the JBPerf P&H injector driver board. Win!
21:03 < simis> They also had neither LM2937 nor LM2941 regulators, but I bought a three pack of LM2940T regulators for $4.99.
21:03 < simis> They seem to be the same as the LM2937, except 1A rather than 500mA.
21:04 < simis> Should be good for CPU power, at least? Pin compatible with the LM2937, though the caps seem to be a little different.
21:06 < simis> I got some 1uF electrolytics and some 100PF ceramic caps as well, on spec. neither will suit the LM2940 example circuit :(
21:06 < simis> Also a hobbyist pack of resistors (I have a bunch of random ones as well), so that should be okay.
21:08 < simis> I'm going to go back for some caps for the PS circuits friday morning, as well as anything else I can figure out.
21:08 < simis> I'm gone next week, but I hope to get this TA board at least powered on and connected the week after.
21:11 < simis> Oh, I got a L7812C-Y regulator (12v) from my buddy as well, do I need clean 12v for the mitsu CAS, or is a feed from the battery enough. The CAS switches the two channels between floating and
ground. That's okay with a 5v source, right? The MS schems have an optoisolator, a 4N25, I bought some of them too, just in case.
21:12 < simis> Sorry to annoy,
21:12 < simis> new circuit builder here.
21:13 < simis> I'll need clean 12v for some of the sensors anyways, right?
21:14 < simis> The LM2941 is mostly for the enable pin, right? Not the adjustablility?
21:15 < simis> Oh, I got a couple of 72 pin .100" headers for the TA board too, they should trim up to 50 pin in the band saw no problem.\
21:18 < simis> Any other stuff I should just buy next time? They have 5.6v zeners and many other things. Throw me some part numbers for cheap stuff that is used a lot and I will pick some up Friday.


Proof I am working, some recent IRC questions.

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Thu Jul 28, 2011 6:17 am
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Great to have you on board, Sim! :-)

sim wrote:
I've divided my goals up into phases, the first phase will be
getting a FreeEMS system up and running and controlling spark
only.

Second phase will be building a pressurized fuel system and
getting the car running on EFI reliably.

Third phase is adding turbocharging. I have manifolds and
turbochargers in my parts bin from several turbocharged Volvo
motors, including two B21FTs, a B230FT from a '89 740T, and a
turbo from a '94 850T (a TDH04-15G).

Almost perfect! :-) I fully endorse the staged approach, especially on a car like this with a carby, it's ideal! You forgot a couple of stages, though :-)

Once you have ignition sorted and working with either 4/1 disk or 24/1 disk, and you've helped me test some enhancements with that, I'd really like you to try the other one, and then, or maybe earlier depending on our French friend, I'd like you to assist in development of the 4/2 CAS decoder - this shouldn't take much effort at all on your part if I'm good :-)

Quote:
I expect to experiment with water/meth injection as well as EGR.

Do you have any ideas about how to compensate for EGR flow and pressure differences over non EGR tune?

Quote:
I want to fully instrument the engine with WBO2 and EGT/cylinder.

16 ADC channels, that shouldn't be a problem.

Quote:
Making thirty-something-year-old cars awesome is a good thing to get into.

They're already awesome, they just need a little TLC to make them really shine :-) My oldest car is 1954, btw.

Quote:
My goals are to roughly double my power, on a stock bottom end
(Volvo redblock motors are good for way more) and, ultimately,
double my fuel economy. Resulting in a fun and economical
roadtrip machine (Canada is a large country).

The first part should be trivial to achieve, and the latter not tooooo difficult, hopefully.

Quote:
http://puddle.ca/~sim/volvo/img/SimeonVeldstra1979245-2.jpg
My wagon, on a forest road outside of Thunder Bay, Ontario.

She looks great! :-)

sim wrote:
21:01 < simis> They only had the inverting version of 74HC[367,368] in stock, so I picked up two SN74HC241N chips for $0.88 instead.
21:02 < simis> It occurs to me that line drivers will suit not only the LS1 coils, but also the JBPerf P&H injector driver board. Win!

Yep, it'll work well enough for both, while protecting the CPU, but it definitely will not drive normal ignitors properly, just FYI. Additionally, rather than an XOR on the input (24/1 will work without inversion, but 4/1 and 4/2 must have the correct polarity) you could use the inverting 367/368 for input instead. Is that clear enough?

Quote:
21:03 < simis> They also had neither LM2937 nor LM2941 regulators, but I bought a three pack of LM2940T regulators for $4.99.
21:03 < simis> They seem to be the same as the LM2937, except 1A rather than 500mA.
21:04 < simis> Should be good for CPU power, at least? Pin compatible with the LM2937, though the caps seem to be a little different.
21:14 < simis> The LM2941 is mostly for the enable pin, right? Not the adjustablility?

2937 just draws less itself while doing its job (lower quiescent current) and 2941, as you say, just has switchable enable/disable which you dont need, you can get away with single on/off with key supply on this, unless you want to upgrade later, so 2937 and 2940 are the same to you, for all intents and purposes. You got the right thing :-)


Quote:
21:06 < simis> I got some 1uF electrolytics and some 100PF ceramic caps as well, on spec. neither will suit the LM2940 example circuit :(
21:08 < simis> I'm going to go back for some caps for the PS circuits friday morning, as well as anything else I can figure out.

Yeah, go a bit bigger (22uF inside and 10uF outside or more) and make sure the electro/tant ones on the 5v side are twice as big as the 12v side. Standard 50v 0.1uF ceramics are probably ideal for the HF decouplers for both sides.

Quote:
21:11 < simis> Oh, I got a L7812C-Y regulator (12v) from my buddy as well, do I need clean 12v for the mitsu CAS, or is a feed from the battery enough. The CAS switches the two channels between floating and ground. That's okay with a 5v source, right? The MS schems have an optoisolator, a 4N25, I bought some of them too, just in case.

No need, dirty battery 12v is fine, a regulator could do you harm and wont do you good. Ground the CAS to the same place you ground the FreeEMS setup, though. Because you're using external drivers for both inj and ign you can get away with a single ground to your freeems without issue. You don't need an opto isolator, though now that you have them, you could use them to invert the signal, which IS necessary for the 4/1 and 4/2 decoders. The inputs from the CAS should have 1k pullups to 5v on them. As you say, the CAS pulls those down to 0v creating the square wave. Let me know if you need more info.

Quote:
21:12 < simis> Sorry to annoy,
21:12 < simis> new circuit builder here.

You're not annoying, this is exciting news! You could be engine number 6! You could also be first sequential! Not to mention first 4/2 user. You're going to be our most useful tester yet :-)

Quote:
21:13 < simis> I'll need clean 12v for some of the sensors anyways, right?

I don't understand, but typically there is no such thing as clean 12v on a car, as you can't regulate to 12v under all operating conditions. Temp sensors are pulled up to 5v with precision resistors. MAP and TPS take 5v, wideband runs off raw 12v (do you have one, btw? which type?) You'll probably want an AAP (second MAP) sensor at some point, if it's going to be a Canada road trip car, but we can add that later. It can be the same as the other one you get, whatever that is. Toyota, GM, whatever else. Battery ref is obviously raw 12v. I hope that helps.

Quote:
21:15 < simis> Oh, I got a couple of 72 pin .100" headers for the TA board too, they should trim up to 50 pin in the band saw no problem.

Perfect.

Quote:
21:18 < simis> Any other stuff I should just buy next time? They have 5.6v zeners and many other things. Throw me some part numbers for cheap stuff that is used a lot and I will pick some up Friday.

I'll try to think this over more today, but in the mean time, here are two older threads with some wrong and some good info in them:

viewtopic.php?f=9&t=1096
viewtopic.php?f=9&t=1139

I'll try to edit them to be correct later today if I get a chance, but take what you've heard more recently over what is in those old threads.

Fred.

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Thu Jul 28, 2011 10:08 am
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Oh, and re the resistors, for some stuff precision is important, and they're so cheap anyway, I'd recommend the blue 1% metal film jobs for everything. Often they have higher power handling too in the same body size. If you use cheap carbon ones, things like batt V and temps will be a bit more off compared to what they should be. (upto ~5x worse).

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Thu Jul 28, 2011 10:10 am
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Oh, and one last thing, request for some pics/info/links/description about your Joshifab mitsi CAS setup for those who don't know (I know, but others won't). Pretty please :-)

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Thu Jul 28, 2011 10:23 am
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Fred wrote:
Great to have you on board, Sim! :-)

Thanks, it's good to be here.

sim wrote:
I've divided my goals up into phases, the first phase will be
getting a FreeEMS system up and running and controlling spark
only.

Second phase will be building a pressurized fuel system and
getting the car running on EFI reliably.

Third phase is adding turbocharging. I have manifolds and
turbochargers in my parts bin from several turbocharged Volvo
motors, including two B21FTs, a B230FT from a '89 740T, and a
turbo from a '94 850T (a TDH04-15G).


Quote:
Quote:
I expect to experiment with water/meth injection as well as EGR.

Do you have any ideas about how to compensate for EGR flow and
pressure differences over non EGR tune?


Nope, both of these things are well beyond my current scope. Once
I get spark and fuel sorted, I can start experimenting. Hopefully
I won't have to invoke a spare engine.

Quote:
Quote:
I want to fully instrument the engine with WBO2 and EGT/cylinder.

16 ADC channels, that shouldn't be a problem.

Quote:
Making thirty-something-year-old cars awesome is a good thing to get into.

They're already awesome, they just need a little TLC to make them really shine :-) My oldest car is 1954, btw.


Yes, they are already awesome. I love to drive my '79 wagon,
even stock.

Quote:
Quote:
My goals are to roughly double my power, on a stock bottom end
(Volvo redblock motors are good for way more) and, ultimately,
double my fuel economy. Resulting in a fun and economical
roadtrip machine (Canada is a large country).

The first part should be trivial to achieve, and the latter not tooooo difficult, hopefully.


Yes, 200HP is easy for these motors. Doubling the economy is kind
of cheating, as I have documented my current set-up as a gas
guzzler. Doubling economy should be doable, if not easy.


Quote:
Quote:
http://puddle.ca/~sim/volvo/img/SimeonVeldstra1979245-2.jpg
My wagon, on a forest road outside of Thunder Bay, Ontario.

She looks great! :-)

Thank you!

Quote:
sim wrote:
21:01 < simis> They only had the inverting version of 74HC[367,368] in stock, so I picked up two SN74HC241N chips for $0.88 instead.
21:02 < simis> It occurs to me that line drivers will suit not only the LS1 coils, but also the JBPerf P&H injector driver board. Win!

Yep, it'll work well enough for both, while protecting the CPU, but it definitely will not drive normal ignitors properly, just FYI. Additionally, rather than an XOR on the input (24/1 will work without inversion, but 4/1 and 4/2 must have the correct polarity) you could use the inverting 367/368 for input instead. Is that clear enough?

Yeah, I picked the coils to be easy.

I will look into the CAS inputs further before commiting to a
circuit.

Quote:
Quote:
21:03 < simis> They also had neither LM2937 nor LM2941 regulators, but I bought a three pack of LM2940T regulators for $4.99.
21:03 < simis> They seem to be the same as the LM2937, except 1A rather than 500mA.
21:04 < simis> Should be good for CPU power, at least? Pin compatible with the LM2937, though the caps seem to be a little different.
21:14 < simis> The LM2941 is mostly for the enable pin, right? Not the adjustablility?

2937 just draws less itself while doing its job (lower quiescent current) and 2941, as you say, just has switchable enable/disable which you dont need, you can get away with single on/off with key supply on this, unless you want to upgrade later, so 2937 and 2940 are the same to you, for all intents and purposes. You got the right thing :-)


Excellent. I would like to set myself up to have the always-on
features. Not important now though. 1amp > 0.5amp, to be sure.


Quote:
Quote:
21:06 < simis> I got some 1uF electrolytics and some 100PF ceramic caps as well, on spec. neither will suit the LM2940 example circuit :(
21:08 < simis> I'm going to go back for some caps for the PS circuits friday morning, as well as anything else I can figure out.

Yeah, go a bit bigger (22uF inside and 10uF outside or more) and make sure the electro/tant ones on the 5v side are twice as big as the 12v side. Standard 50v 0.1uF ceramics are probably ideal for the HF decouplers for both sides.


I will get some more caps.

Quote:
Quote:
21:11 < simis> Oh, I got a L7812C-Y regulator (12v) from my buddy as well, do I need clean 12v for the mitsu CAS, or is a feed from the battery enough. The CAS switches the two channels between floating and ground. That's okay with a 5v source, right? The MS schems have an optoisolator, a 4N25, I bought some of them too, just in case.

No need, dirty battery 12v is fine, a regulator could do you harm and wont do you good. Ground the CAS to the same place you ground the FreeEMS setup, though. Because you're using external drivers for both inj and ign you can get away with a single ground to your freeems without issue. You don't need an opto isolator, though now that you have them, you could use them to invert the signal, which IS necessary for the 4/1 and 4/2 decoders. The inputs from the CAS should have 1k pullups to 5v on them. As you say, the CAS pulls those down to 0v creating the square wave. Let me know if you need more info.


Makes sense to me.

Quote:
Quote:
21:12 < simis> Sorry to annoy,
21:12 < simis> new circuit builder here.

You're not annoying, this is exciting news! You could be engine number 6! You could also be first sequential! Not to mention first 4/2 user. You're going to be our most useful tester yet :-)


Engine number six would rock.

Quote:
Quote:
21:13 < simis> I'll need clean 12v for some of the sensors anyways, right?

I don't understand, but typically there is no such thing as clean 12v on a car, as you can't regulate to 12v under all operating conditions. Temp sensors are pulled up to 5v with precision resistors. MAP and TPS take 5v, wideband runs off raw 12v (do you have one, btw? which type?) You'll probably want an AAP (second MAP) sensor at some point, if it's going to be a Canada road trip car, but we can add that later. It can be the same as the other one you get, whatever that is. Toyota, GM, whatever else. Battery ref is obviously raw 12v. I hope that helps.


This makes sense.

Thanks for the reply Fred.

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Fri Jul 29, 2011 10:30 am
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You're welcome, let me know what you need.

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Fri Jul 29, 2011 11:22 am
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Firstly, from IRC, for others following this guide-in-progress:

Quote:
[00:10] <simis> Fred: What do I need to do to bypass the on-board regulator on the TA? Is it as simple as bridging the two outside pins?
[00:11] <Fred> yep! i used a piece of copper leg off of a big diode or something and cut the centre one off short as it was easier than desoldering a 3 legged device
[00:12] <Fred> i recommend feeding power and ground in through the 2 pin plug or the back side of it
[00:12] <Fred> NOT through the header pins
[00:12] <Fred> the traces are no good there
[00:13] <simis> So snip the ground and bridge the two outside pins on the regulator.
[00:14] <simis> I see the power header pins, but not the two pin plug you speak of.
[00:15] <Fred> its white and close to the reg, there are other ones with other pin counts on it
[00:16] <simis> Oh yeah, that's a plug, not a header, I guess. Where you are supposed to connect 6-12v, right?
[00:16] <Fred> right
[00:16] <Fred> sorry
[00:16] <Fred> header/socket/plug
[00:16] <Fred> make sure it only ever gets 5v in future!
[00:17] <simis> This TA board has a LM2937ET on it, that's th 500mA version of the LM2940 I'm using, right?
[00:17] <simis> Could I just replace the reg with the 1A version? (too late now anyway, I've built the power supply).
[00:18] <simis> Okay, I'm clear on what to do, back to the garage.
[00:18] <simis> Thanks Fred.
[00:22] <Fred> simis: shit... the earlier ones had shit regs on them that were throw away jobs
[00:22] <Fred> you could have desoldered that and just used it
[00:22] <Fred> sorry
[00:22] <Fred> :-(
[00:23] <simis> Ha, serves me right for not bending the thing over and looking, I have a vague recollection of hearing that the TA board PS was upgraded, perhaps after your complaints.
[00:23] <simis> No matter, a couple of bucks worth of parts.
[00:25] <Fred> yeah, i remember such a thing too, but never saw it first hand
[00:25] <Fred> quite possibly my complaints, yes
[00:25] <Fred> :-)


The morals of that story are:

  • Check to see if you can reuse your existing regulator by desoldering and relocating it. Desoldering isn't that easy, but isn't that hard either.
  • Feed your high quality 5v supply in through the old 12v input pins, NOT through the H1/H2 headers which have thin traces.

Right, onto the next stuff that I didn't answer yet!

Fred.

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Fri Aug 12, 2011 6:12 pm
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Quote:
[02:05] <simis> Fred: Are you still there? TA board is powered and working, I have some questions about line drivers.

Nope, I was asleep! GREAT to hear that you're making progress! :-) NP about questions, let's get that done:

Quote:
[02:05] <simis> I've got a couple each of SN74HC241N and MC14503BPC.
[02:06] <simis> The 74HC241 has eight drivers in the package, so one chip will do four ignition channels and four fuel channels.
[02:07] <simis> The 14503 has six drivers in the package, in a bank of two and a bank of 4, but it seems to be able to drive more current, 25mA per pin as opposed to ~6mA/pin if I'm reading the datasheets correctly.

I would suggest using the stronger one! If you use the weaker one you're only doing double what the CPU can do itself, so you're not improving potential performance, JUST protecting the CPU. I mentioned that when you bought those weaker ones.

To be safe with each means the following:

6mA: 5V / 0.006A = 833.333333 Ohms
25mA: 5V / 0.025A = 200 Ohms

150 - 330 are probably good values to protect the IC and drive the devices properly.

Quote:
[02:08] <simis> Anyone have any idea how much current a LS1 coil needs? Or the JBPerf injector driver board?

It's more about having greater authority over the line. The P&H board can be driven with something pretty weak, but the weaker the drive the higher the chance of induced currents and voltages causing output switching. At 200 Ohms you should be happy and safe for both devices.

Quote:
[02:09] <simis> I am assuming all I need to do with these drivers is put a 1K resistor between the TA pin and the driver input? Is that correct?

Yes, that is correct.

Quote:
[02:10] <simis> What is a good way to add in an LED? Pre-driver, or post?

Post! The CPU is pretty weak and if you drive an LED your drive for the output is reduced.

Quote:
[02:13] <simis> Oh yeah, and what pins am I hooking the coils up to? (I'd like to build the injector circuits now too)
[02:15] <simis> Looks like RavAGE is using port T?

Correct! T2-7 are the outputs right now. Make sure that it's easy to change to other pins if/when required, but hook the 2 or 4 ignition drivers to T2 T3 T4 T5 in that order and the balance to your injector drivers in that order too (T4, T5, 56 T7). Remember 2 of one 4 of the other, take your pick which way around you want it.

Quote:
[07:24] <simis> Hmm, based on screwing around with my mitsu CAS, it looks like this thing pulls the outputs to ground when the window is open, when there is a hole between the light source and reciever.

Correct! You need a 1k pull up on those inputs, and you need to invert that signal to the CPU, though for 24/1 testing you don't care about the polarity. For 4/2 and 4/1 testing you need the polarity correct.

Quote:
[07:27] <simis> The sketch in my notebook indicates a 100pF cap between the line driver output and ground, I can install this in the board, right? I figure it is better to put it in as it will be easier to cut it out than add it later.

Where did you get this from? This is possibly a good idea however you need to be aware that this WILL skew the output timing slightly as the series resistor charges the cap and discharges it again.

Quote:
[07:41] <simis> MCU --> 1k Ohm --> Line Driver --> tee(LS1 coil) --> 100pF cap --> GND

I'd skip the cap for now, you can add it later, leave room if you want.

Quote:
[07:41] <simis> Pretty simple. God, I wish I knew what I was doing enough to just solder it up.
[07:42] <simis> If that is all it takes, I've got it layed out on veroboard ready to go.
[08:00] <simis> http://puddle.ca/~sim/volvo/FreeEMS/Fre ... nitial.jpg
[08:03] <simis> TA board, installed on sockets that are soldered into veroboard, with power supply, power to the CAS, and a line driver chip stuck into the board awaiting soldering.

Yep, it's that simple! :-) GREAT work man! :-)

Quote:
[18:28] <Fred> you'll have it before you finish work, i promise
[18:28] <simis> Great! Thanks for all the help Fred.

Done!

Fred.

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Fri Aug 12, 2011 6:29 pm
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For the record re analogue protection stuff:

Quote:
[18:29] <simis> It looks like I need some zeners and shottkys for some of the analog in circuits, anything I can pick up on my way in today?
[18:35] <Fred> well, you don't need them if your wiring is good
[18:35] <Fred> they're purely for wiring fuckups
[18:36] <Fred> 12v applied to input while creating loom etc
[18:36] <Fred> zeners, no, only on digital stuff, and then only carefully
[18:36] <seank-efi> a classic mistake
[18:37] <Fred> schottkys yes, good idea, if you want to make your temporary rig robust or its a true diy permanent effort
[18:37] <Fred> :-)
[18:37] <Fred> be careful about leakage
[18:37] <Fred> simis: ^
[18:38] <simis> Yeah, that sounds like the kind of fuckup I am well capable of.
[18:38] <Fred> LOL
[18:38] <simis> Got a part number for diodes to pick up?
[18:39] <Fred> schottkys arent that common, so no, i dont
[18:39] <Fred> i dont even know roughtly off the top of my head
[18:39] <Fred> normal diodes arent a lot of use as they have too high of a v drop
[18:39] <simis> Okay, no problem.
[18:39] <Fred> the chip has diodes built in
[18:39] <Fred> normal ones will share the load with those, but one might take more than the other and you cant know which
[18:39] <simis> The driver chip, yeah.
[18:39] <simis> I'm thinking ahead to CHT, IAT, etc.
[18:40] <Fred> schottkys will take the whole load as they drop 0.3v or so and catch stuff before the chip diodes see it
[18:40] <Fred> sorry
[18:40] <simis> I still need to get sensors for much of that stuff though.
[18:40] <Fred> by chip i mean cpu

Can anyone suggest some common garden north american schottky part numbers with low enough leakage for analogue protection? That'd be helpful! :-)

Fred.

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The ever growing list of FreeEMS success stories!


Fri Aug 12, 2011 6:30 pm
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