Public-domain OBD1 PCB board - ORDER HERE
09-21-2006, 07:52 PM
#167
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Hi,
I'm getting close to being done on assembling my board. I have a question though:
The BOM states I need a "C1 0.1uF 25 Volt (such as Vishay A104K15X7RF5TAA or K104Z15Y5VE5TL2)" but the only thing I could find at Radio Shack was was a 0.1uF metalized film capacitor that is rated at 250WVDC max. Can I use that one instead? Or will it blow up my car's computer? Is that number maximum input (which it will never see in this application) or an output level that will destroy stuff?
Many thanks in advance. I am a complete electronics newbie...
Thaddeus
I'm getting close to being done on assembling my board. I have a question though:
The BOM states I need a "C1 0.1uF 25 Volt (such as Vishay A104K15X7RF5TAA or K104Z15Y5VE5TL2)" but the only thing I could find at Radio Shack was was a 0.1uF metalized film capacitor that is rated at 250WVDC max. Can I use that one instead? Or will it blow up my car's computer? Is that number maximum input (which it will never see in this application) or an output level that will destroy stuff?
Many thanks in advance. I am a complete electronics newbie...
Thaddeus
09-21-2006, 08:11 PM
#169
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Thaddeus: the capacitor voltage rating is a max working voltage. The cap looks like it's there merely to filter out noise from the ~12VDC power supply. I'm putting in a 100uF and a .1uF.
William: the pcb has locations for the leds, labeled L1, L2, L3.
P.S.: I'm only answering these Qs because I think I can, not because I'm an expert on this circuit. I'm still building mine (gotta get the connectors and one transistor and a box).
William: the pcb has locations for the leds, labeled L1, L2, L3.
P.S.: I'm only answering these Qs because I think I can, not because I'm an expert on this circuit. I'm still building mine (gotta get the connectors and one transistor and a box).
09-21-2006, 08:19 PM
#171
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Originally Posted by brucec59
Thaddeus: the capacitor voltage rating is a max working voltage. The cap looks like it's there merely to filter out noise from the ~12VDC power supply. I'm putting in a 100uF and a .1uF.
09-21-2006, 08:38 PM
#172
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Originally Posted by Lorenfb
"What does the knock detection signal on pin 11 look like? Data, analog?"
That output is a data output which provides a knock count per 10K cylinder ignitions.
At 3000 RPMs, it takes about a minute to do the sampling, i.e:
Time = 10,000 / (3,000 RPMs X 3 (fires/rev) ~= 1 min.
On the PST2, it provides a progression indication (moving bar) and the number of knocks
at the end of the sample period. Usefiul data only results under heavy load,
high temperatures, & with a standard/normal octane being used. The Hammer
provides a similar output.
That output is a data output which provides a knock count per 10K cylinder ignitions.
At 3000 RPMs, it takes about a minute to do the sampling, i.e:
Time = 10,000 / (3,000 RPMs X 3 (fires/rev) ~= 1 min.
On the PST2, it provides a progression indication (moving bar) and the number of knocks
at the end of the sample period. Usefiul data only results under heavy load,
high temperatures, & with a standard/normal octane being used. The Hammer
provides a similar output.
i.e. the Motronic only gives fault codes, etc when polled and addressed.
I'm thinking I could convert pin 11 from OBD to RS232 then connect HyperTerminal to monitor this data and store it. It would be simpler to do without also connecting scantool to poll 'wakeup' Motronic.
It seems it might be easier to monitor the ignition timing to see if it is being retarded. The ignition timing is a output of Motronic.
Ray
09-21-2006, 09:20 PM
#173
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Originally Posted by Thaddeus
Hi,
I'm getting close to being done on assembling my board. I have a question though:
The BOM states I need a "C1 0.1uF 25 Volt (such as Vishay A104K15X7RF5TAA or K104Z15Y5VE5TL2)" but the only thing I could find at Radio Shack was was a 0.1uF metalized film capacitor that is rated at 250WVDC max. Can I use that one instead? Or will it blow up my car's computer? Is that number maximum input (which it will never see in this application) or an output level that will destroy stuff?
Many thanks in advance. I am a complete electronics newbie...
Thaddeus
I'm getting close to being done on assembling my board. I have a question though:
The BOM states I need a "C1 0.1uF 25 Volt (such as Vishay A104K15X7RF5TAA or K104Z15Y5VE5TL2)" but the only thing I could find at Radio Shack was was a 0.1uF metalized film capacitor that is rated at 250WVDC max. Can I use that one instead? Or will it blow up my car's computer? Is that number maximum input (which it will never see in this application) or an output level that will destroy stuff?
Many thanks in advance. I am a complete electronics newbie...
Thaddeus
The RS232 serial port is not liable to get damaged regardless of what you might do wrong. The PC is safe. The OBD connector does have a supply voltage, +12V. With the interface fuse in series with +12V, OBD will be safe regardless with what you do. The only part that will die if installed incorrectly is the 100uF. It wouldn't hurt anything else (maybe the fuse). The -V lead must be connected to 0V, and the DC working voltage must be greater than the battery/charger max voltage.
Ray
09-21-2006, 09:28 PM
#174
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Ray, what does that mean 'the -V lead mus be connected to 0V? What is it on the corcuit board, and what do I connect it to?
Also: there's a printed thing n the lower left hand corner of the board that says 'on recv cut'... am I supposed to cut the printed conductor there?
I'm really sorry for asking such stupid questions...
Also: there's a printed thing n the lower left hand corner of the board that says 'on recv cut'... am I supposed to cut the printed conductor there?
I'm really sorry for asking such stupid questions...
09-21-2006, 10:26 PM
#175
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Originally Posted by Thaddeus
Ray, what does that mean 'the -V lead mus be connected to 0V? What is it on the corcuit board, and what do I connect it to?
Also: there's a printed thing n the lower left hand corner of the board that says 'on recv cut'... am I supposed to cut the printed conductor there?
09-21-2006, 11:01 PM
#176
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Originally Posted by cowtown
Connect OBD pin5 lead to the board where it says "OBD5 0V"
Originally Posted by cowtown
No, don't cut it. That's for an optional thing that Ray can explain better than I can.
09-21-2006, 11:03 PM
#177
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Originally Posted by Thaddeus
if I can just get to the point where I can clear my 2 minute-long airbag warning light, I'll be happy.
Colin
09-22-2006, 10:56 AM
#178
"Thanks, do you know if pin 11 constantly provides data without being asked?"
The tester must request the start of the sampling period.
You can verify this by connecting a scope to pin 11.
During the sampling period, just the progress data (indication bar)
are provided/updated/outputed. It's only at the end, does the actual knock
data/count get outputed.
The tester must request the start of the sampling period.
You can verify this by connecting a scope to pin 11.
During the sampling period, just the progress data (indication bar)
are provided/updated/outputed. It's only at the end, does the actual knock
data/count get outputed.
09-22-2006, 03:01 PM
#179
Ray,
I believe the knock sensor output on pin 11 provides a instant high to low transition when the ecu detects a knock signal with the correct frequency components. I use this signal output into a simple binary counter cct to determine the number of knocks detected over a period of time. The pulses are short and sync'd to cylinders. It is not transmitted with any protocol around it. I do not know about the counting system within the ECU that is mentoned above. If the counter escalates up I take my foot off the accelerator. Saved me I'm sure a few times with the SC. Compensating for knock with the w/a injection helps alot and kills the knock detected. Now left with a little transitional knock but working through that by retarding the injection as it gets on boost. When I did get a sitution when I could hear the knock (a single ping)the counter was really going for it so I think it is a realistic measure.
BR, Mark.
I believe the knock sensor output on pin 11 provides a instant high to low transition when the ecu detects a knock signal with the correct frequency components. I use this signal output into a simple binary counter cct to determine the number of knocks detected over a period of time. The pulses are short and sync'd to cylinders. It is not transmitted with any protocol around it. I do not know about the counting system within the ECU that is mentoned above. If the counter escalates up I take my foot off the accelerator. Saved me I'm sure a few times with the SC. Compensating for knock with the w/a injection helps alot and kills the knock detected. Now left with a little transitional knock but working through that by retarding the injection as it gets on boost. When I did get a sitution when I could hear the knock (a single ping)the counter was really going for it so I think it is a realistic measure.
BR, Mark.
Last edited by E6MPB; 09-22-2006 at 03:50 PM.
09-22-2006, 07:47 PM
#180
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OK, hopefully my last question:
The only 100 uf capacitor I have been able to find is one of those barrels. I understand these are polarized and must be installed oriented properly. I have identified the negative lead on the capacitor.
(1) can I use this type?
(2) If I can use this type of capacitor, which way do I put it in this specific board so that it will be oriented correctly?
(3) Can I mix capacitor types, i.e.I have a small flat ceramic capacitor for the .01uf one, and the barrel type for the 100 uf. Is it OK to mix them on the same circuit like this?
thanks...
Electronics Newbie Moron Boy
The only 100 uf capacitor I have been able to find is one of those barrels. I understand these are polarized and must be installed oriented properly. I have identified the negative lead on the capacitor.
(1) can I use this type?
(2) If I can use this type of capacitor, which way do I put it in this specific board so that it will be oriented correctly?
(3) Can I mix capacitor types, i.e.I have a small flat ceramic capacitor for the .01uf one, and the barrel type for the 100 uf. Is it OK to mix them on the same circuit like this?
thanks...
Electronics Newbie Moron Boy