holden DIS RPM output 12v or 5v

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delcowizzid
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holden DIS RPM output 12v or 5v

Post by delcowizzid »

just wondering if the RPM pulses output from the holden DIS ignition module sprout wire is 12 volts or 5 volts as im about to connect it to my wideband and need to know if i need to install my voltage convertor circuit to cut it down to 5 volts or not cheers
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VL400
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Re: holden DIS RPM output 12v or 5v

Post by VL400 »

See the attached pic, top trace is the signal from the ignition module (or DIS) going to the ECM, the middle trace is the signal from the ECM to the ignition module for timing/dwell control and the bottom trace is the bypass line.

Ignition Module ---> ECM = 12V square wave
ECM ---> Ignition Module = 5V Square wave
Bypass Line = 5V when ECM controls timing, 0V when module is in charge (ie cranking or failsafe/bypass mode)


What are you using for voltage conversion? A resistor and zener diode would do the job nicely.
Attachments
Trace Showing DREF EST and Bypass.gif
Trace Showing DREF EST and Bypass.gif (3.88 KiB) Viewed 5906 times
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delcowizzid
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Re: holden DIS RPM output 12v or 5v

Post by delcowizzid »

Im planning either of these 2 circuits the first one is know to work and outputs about 5.1-5.2 volts the second has been known to not limit volts so ill probably just go the first one.I was going to connect to the sprout in the engine bay but if i can go direct to the wire from the module to the ecu even better I had thought about it but wasnt sure on what sort of signal it was and weather i might pull too much current off the line might still goto the rpm sprout or the wiring to the indash rev counter yet.as long as its 0-5 volt square wave when its at my wideband input its fine ive been told 5.2 is ok too if thats as low as i can get it.the second one would have better noise filtering but I dont have time to mess round checking if its working so i might just go with the zenor and resistor for now
zenerregulatorbt3.jpg
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rpminputjawvn8.gif
rpminputjawvn8.gif (8.17 KiB) Viewed 5904 times
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
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VL400
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Re: holden DIS RPM output 12v or 5v

Post by VL400 »

Regardless of where your grabbing the signal from just run something like what you posted - either circuit will do the same job. Just dont use too much capacitance for filtering and keep the resistor high enough in value to not pull the signal down.
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delcowizzid
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Re: holden DIS RPM output 12v or 5v

Post by delcowizzid »

so you think 270ohms is all good im going to do a shop up tomorrow for some parts hope they have them in stock or i will be logging blind .why does one circuit have a 270ohm but the other 10k is that just cause of the capacitor and how the circuit works
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VL400
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Re: holden DIS RPM output 12v or 5v

Post by VL400 »

Id try with a 10k to start with, its there for current limiting - the higher the better. Grab some 1k resistors also.
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delcowizzid
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Re: holden DIS RPM output 12v or 5v

Post by delcowizzid »

sweet as i have 10k's so ill get some 1k's and a couple of zeners and a replacement zener for the jaw while im there and the LM3904 5 volt reg i need too cheers mate
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blownvp
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Re: holden DIS RPM output 12v or 5v

Post by blownvp »

im pretty sure the tacho output wire from dfi module for v6 is a 5v square wave.
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delcowizzid
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Re: holden DIS RPM output 12v or 5v

Post by delcowizzid »

i might slap the multimeter on it on the weekend and see i hear you get the average volts displayed doing that so it should be around 2-3 volts if its a 5 volt signal
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delcowizzid
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Re: holden DIS RPM output 12v or 5v

Post by delcowizzid »

right i have built the 1 resistor 1 diode circuit into my cable will hopefully be testing on the weekend.
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
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