Circuit for counting ignition pulses with inductive pickup using LM2907

Thread Starter

Ahoo

Joined Sep 28, 2014
33
Hi

I haven't actually measured the field around a spark plug wire, but its strong enough to be sensed by a wire wrap or inductive pickup, so it can easily be sensed by a hall sensor.
In addition, the circuitry used for spark sensing must include signal conditioning before input to the remaining circuitry (ADC or otherwise). The A1203 is a hall bipolar switch that already contains conditioning circuitry. It can provides a pulsed DC output (triggered by the sensed spark) at whatever output voltage level needed (up to 30vdc). Cost is about 1.80 USD for the SIP version.



You could send the output of the hall sensor directly to the input of the Arduino (with appropriate overvoltage protection), compute the measured RPM, then display on an LCD, LM3914 with LEDs, or other display device. I haven't used Arduino before, only PIC micro's. Maybe someone else in this forum can help.

eT
Thank you so much eetech00
I really appreciate your contribution to this thread and hope you will be doing the same on this whole forum..
I am attaching a file which I took from some where else... I just want you to compare it with your provided circuit in post #22 and tell me what is the difference between these two besides the voltage regulator circuit.

What do you think If I replace the UGN3030T in this circuit with A1203..... will it work????????


Hall sensor tapped on spark plug wire.JPG
 

cmartinez

Joined Jan 17, 2007
8,286
Ahoo,
I've compared the UGN3030T and the A1203 datasheets, and they seem to be a very similar match. I think it's perfectly ok if you were to substitute the UGN3030T for the A1203... there shouldn't be a problem with that...
If you wish to compare the datasheets yourself, you can find them here, and here.
 

Thread Starter

Ahoo

Joined Sep 28, 2014
33
Ahoo,
I've compared the UGN3030T and the A1203 datasheets, and they seem to be a very similar match. I think it's perfectly ok if you were to substitute the UGN3030T for the A1203... there shouldn't be a problem with that...
If you wish to compare the datasheets yourself, you can find them here, and here.
Cmartinez
Can you thrw some light on the circuit pr0vided by eetech00 in post #22 and the one I have attached in post #41. Like I mean to say that the circuit for LM2917 in eetech00 circuit is quite complicated as compared to the circuit in eetech00 post#22.
 

cmartinez

Joined Jan 17, 2007
8,286
Cmartinez
Can you thrw some light on the circuit pr0vided by eetech00 in post #22 and the one I have attached in post #41. Like I mean to say that the circuit for LM2917 in eetech00 circuit is quite complicated as compared to the circuit in eetech00 post#22.
Well, both circuits are basically the same, but the circuit in post 22 is heavily filtered while the one in 41 is simpler. On the other side, circuit 41 is omitting the 9V regulator that circuit 22 shows by using an LM317. Frankly, I'd go for circuit 41, out of sheer simplicity, since it's a circuit that you can easily test with an ordinary voltmeter.
And here's a little advice... questions and answers on this forum can only get you so far... If I were you, I'd simply make up my mind and try to build the thing already. In my experience, the best way to learn electronics is through a hands-on approach. I suggest you get yourself a simple voltmeter, buy the components, and start doing some experimenting. Remember, the longest of journeys always starts with the first step.
Happy experimenting
 

debe

Joined Sep 21, 2010
1,390
This is the circuit I used for a tacho on a diesel engine in a boat. The hall device was triggered by a magnet stuck on the crank pulley. You don't need fancy circuits on the 12v supply line, as ive used this basic circuit in vehicles aswell. The last picture is using a coil to trigger the hall for calibration purposes & 50Hz, which gives 3000rpm in this application.Tacho 3.JPG Tacho 4.JPG Tacho 5.JPG
 

eetech00

Joined Jun 8, 2013
4,056
Thank you so much eetech00
I really appreciate your contribution to this thread and hope you will be doing the same on this whole forum..
I am attaching a file which I took from some where else... I just want you to compare it with your provided circuit in post #22 and tell me what is the difference between these two besides the voltage regulator circuit.

What do you think If I replace the UGN3030T in this circuit with A1203..... will it work????????


View attachment 74046
Hi:)

The A1203 can replace the UGN3030. The UGN303o is discontinued

The values in the diagram don't look right:
For the values you gave me, 4000RPM=33.3333Hz and want that to be 4v full scale (1mv/RPM).

So, with the values shown in that diagram:

9v*33.3333*0.00000047*147000*1=20.726979273 (??)o_O

Just use the circuit in the post #22, I know that will work.

eT
 

eetech00

Joined Jun 8, 2013
4,056
And here's a little advice... questions and answers on this forum can only get you so far... If I were you, I'd simply make up my mind and try to build the thing already. In my experience, the best way to learn electronics is through a hands-on approach. I suggest you get yourself a simple voltmeter, buy the components, and start doing some experimenting. Remember, the longest of journeys always starts with the first step.
Happy experimenting
That is excellent advice!
Knowledge is gained thru experience. At some point you have to go for it...:)

eT :cool:
 

Thread Starter

Ahoo

Joined Sep 28, 2014
33
If you want the frequency why not just square-up the pulses with a comparator and then count the digital pulses with the Arduino? Converting the pulses to voltage seems an unnecessary step.
hi crutschow
can you help counting the pulses with arduino as I am not good in programming????
 

Thread Starter

Ahoo

Joined Sep 28, 2014
33
Hi

It looks like the TI "DRV5023" Digital-Switch Hall Effect Sensor should work.

eT
hey eetech00 can you please help finding a good store in phila to buy A1203 or DRV5023. I went on Digikey but they were asking for customer reference nember and I dont know what it is.... ALso it will cost me for shipment too.... So can you tell me any store where I can buy it....
 

Thread Starter

Ahoo

Joined Sep 28, 2014
33
hi eetech00
I got the IC's.... Now am staring to work on them... but I am a little confused with that 50k pot... grounding two legs of pot will make two resistance paths ...one complete 50k and the other adjusted resistance path form pin 3 through R1... Is it correct ??? what I mean to say is that with this configuration 50k path is always available independent of the position of potentiometer adjusted leg. like current has to take two paths ... should'nt it be like it has to only pass thro adjusted leg of potcurrent path at R2 pot.png
 
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