Need some suggestion ignition coil pulse detection

Did any idea how to make ignition coil pulse detection with next :
1. Input via CD 40106 like filter
2. Output with LM 324.
3. All to work at 12V.

Function:

When pulse come to input of CD 40106 in output of LM 324 to we have +12V.
If pulse stop output must drop to 0V

I was look some similar from China but it was hard to make schematic becouse
PCB is to small and two layer SMD.
It is basic for automatic switch from gasoline to LPG in car....
Final end output is relay 12V 10A DC.

I do not want full project from someone but only idea....

Regards.

How it is connected to the ignition coil? On the HV side (with any kind of sensor) or the LV (Tach) side?

If on the LV side, it's plain easy, even a PIC10F would do. Just need to detect a frequency and that's it. 4Cyl tach signal at idle is around 30Hz.

You could check on google for a Frequency To Voltage application, you find it, you're half done, add a comparator at the output of it and you have something that should work.

Quote:

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Originally Posted by mister_e

How it is connected to the ignition coil? On the HV side (with any kind of sensor) or the LV (Tach) side?

If on the LV side, it's plain easy, even a PIC10F would do. Just need to detect a frequency and that's it. 4Cyl tach signal at idle is around 30Hz.

You could check on google for a Frequency To Voltage application, you find it, you're half done, add a comparator at the output of it and you have something that should work.

---

LV side of coil - where is coil switched to gnd to make HV at out.
Triger coil side 12V to 0V signals ....
Thanks

Here is what you need to do:

From the low end of the ignition coil to the anode side of a diode 1N4002, then to Resistor 8.2K then to Resistor 3.9K, then to Basis of a NPN Transistor. A capacitor of 68nF between 8.2K and 3.9K Resistor to ground. A Resistor of 3.9k from Collector to +5Volt, Emitter to Ground. Signal from the Collector to your Circuit.

Code:

---

Coil----Diode-----Resistor 8.2K------Resistor 3.9k-------| Base Transistor
                                  |                  |
                                  |                  |
                                Cap 68nF          Resistor
                                  |                3.9k
                                  |                  |
                                Gnd                Gnd

---

Hope this helps.

My little drawing didn't work too well but you should get the idea...

vBulletin has some tags that can help with that.

The ASCII diagrams work best inside of a code block.

<b>[code]</b>diagram goes here<b>[/code]</b>

hth,

Quote:

---

Originally Posted by misterg

Here is what you need to do:

From the low end of the ignition coil to the anode side of a diode 1N4002, then to Resistor 8.2K then to Resistor 3.9K, then to Basis of a NPN Transistor. A capacitor of 68nF between 8.2K and 3.9K Resistor to ground. A Resistor of 3.9k from Collector to +5Volt, Emitter to Ground. Signal from the Collector to your Circuit.

Code:

---

Coil----Diode-----Resistor 8.2K------Resistor 3.9k-------| Base Transistor
                                  |                  |
                                  |                  |
                                Cap 68nF          Resistor
                                  |                3.9k
                                  |                  |
                                Gnd                Gnd

---

Hope this helps.

---

Thank's I will probe and post what was as result.
Robert

Hi,

You also can use a small relay ( 1 Amp. Omron G5V i.e. ) , placed along the Ignition Coil;

just scope what is going out of the coil pins of the relay ...

oh, surprise ! ... and moreover ... no HV spikes !!!

Alain

Hi Darrel,
thanks for the tip with the code box, appreciate it.
Gunther