Wow! this is getting easier to build.... and harder to understand all the time

but i think i follow what youve done and its very cunning, much slicker than doing it with timers, looking at the 4049's they have 6 internal gates so i only neeed the one ic, then all i need to do is hook power to Vdd and earth to Vss on all three ic's and we are there?

i got some of the bits today i will pick up the rest tomorrow and get to work,
will keep you posted, love your work

 

Yes, print out the data sheets on the two types of CMOS ics. You will have to choose the pin numbers to go with the indicated pin function. Look up the Vdd and Vss pins. Connect Vdd to 12V; Vss to ground. Put a 100nF capacitor between Vdd and Vss in a copuple of places.

 

I have a Quad Frequency Generator DDS chip. Settable from .001 Hz to 39,999.9 Hz. I burn the chip to any set freq, then you power the chip from a 9 volt battery and a lm7805 voltage regulator
Square wave output 50% dutycycle. To get a different dutycycle you could use a CD4017. The output uses 8 pins of the chip (2 each) for the 4 outputs as 1 pin goes high the other goes low (rail to rail)
It is based on the PIC chip with a 20MHZ xtl

 

OK ... think we are gettign it near perfect. just a couple more little Q's

1) all we are concerned with is the rising edges so we might not need the delay, without it will the secondary puls have its rising edge aligned to the falling edge of the primary signal??... if so this is perfect as it is! they are all evenly spaced apart and remain constant at all speeds

2) lastly ...what couple of places should i put the little 100nf capacitors? across all three of the ic's?

cheers

ECU's 101 for anyone interested in following this
Are only concerned with the rising edges of the signals, typically from a pair of reluctors so the signals are quite small also. The ecu generates everything from the multi tooth signal straight off the crankshaft and all the second signal does is tell the ecu to reset and start counting again. If they coincide the ecu can get confused on whether or not to count the coinciding pulse. It resets to the same crankshaft position every second engine revolution (4 stroke eng) hence the single secondary signal is read from the camshaft to syncronise only, being subject to slight mechanical variations from things like belt stretch or timing chain wear etc. The only other major signal the ecu reads is engine is load, typically read directly as manifold vacume or a mass air flow meter on the intake (sometimes straight from throttle position mostly for racing applications) from there the ecu just calculates and applies delays to the ignition timing and duty cycles to the injectors for each cylinder from load/rpm tables adjusting with air and coolent temperatures etc..... engine runs!

 

Here is another tweak. The rising edges are not coincident. I left the pulse width circuit to shorten the SingeTooth signal to less than one MultiTooth period. If you dont care about that, and you could use Fn as the output, you can eliminate D1, C2 & R2, but leave both inverters in the path from Fn to SingleTooth to buffer the signal.

Put the caps right across Vdd and Vss on each IC.

Send a picture when you get it running.

Attached Thumbnails

 

 

ok built it this evening and ill went together wery neat and easy, i have a primary signal but no secondary signal.

i hooked a 2 stage 6 pos rotary switch in the counter loops so i can change the count settings and a pot to alter the rpm. but i think i have the wrong connection for the of the counters

O0 i have used pin 3 zero count output?
the R i have used pin 15 reset (hooked to pole of my switch to loop back different count intervals)
input i have used pin14 clock

maybe i need to put clock enable pin 13 to earth or something??

pics are attached, it will all go in the little box when its done

also why is the signal a bit of an odd shape

cheers

Attached Thumbnails

       

 

COOL.. it all works!!

... once i enabled the clock as i thought, i bumped C2 up to 100n to give a bit bigger secondary signal and its spot on

just have to put all in the little box now

 

I showed the "enable" input to both counters tied to ground (Logic low enables).

Note that you cannot divide by zero (mathematically or practically)

You can divide by One, which is the same as not dividing at all.

You can divide by Ten; however, you will need to connect a pull-down resistor (100K) between the tenth input to the switch and ground. In other words, the counter will naturally divide by Ten if the Reset input is held at ground.

For more flexibility, don't you need a second "divide by" selector switch for the second counter?

The funky output waveform looks like you have a (too-small) capacitor between the logic output and the scope input. Are you running your scope AC-coupled? If so, try it DC-coupled.

 

not sure what my scope is set for, ive only ever used them on 'trigger' setting. the wave form really doesnt matter as long as the ecu regesters the signal, i havn't tried hooking it up to an actual ecu yet. I used a 2 pole rotary switch so it switches both of the counters at once and have just hooked them up to give me divisions of 4,6,12,24,36 and 72 as this will cover most factory triggers like ford GM and toyota etc and cover most custom setups too, enough to play with anyhow, i can add more counters or switches later if i need, aftermarket ecu's are also configorable for any division so its mostly novelty factor because its so easy... same as my 2 little LED indicators

can i get a larger more linier and stable frequency range? the low speed is good but once it gets up high it just sort of instantly runs away very high. for my race car with 36 divisions per 2 revolutions it will go to nearly 2.5KHz at peak rpm. need to make sure the duty cycle of the second signal doesnt go to 100% also as it approaches 70Hz. i dropped the smaller cap back in as i discovered this can happen

cheers ... i love it when things just WORK!

 

The freq of the oscillator is proportional to 1/RC, so as you vary R, the rate of change of frequency will speed up toward one end of a pot. As you indicate, the solution is to use a toggle switch to parallel a second capacitor across the first for the lower frequencies.