I need to program the micro's GPIO to emulate an output of a Tachometer and feed it into a RPM pickup bolted on a Dyno jet 250i (clickable link takes to Dynojet 250i manual), On page number 132 we can see that the RPM pickup is a inductive pickup. Also, I'm worried of the fact that the warning on the Manual says :
"Inductive pickups are very fragile. The ferrite core can easily be damaged and is not covered under warranty. Dropping, snapping, vibration, and heat can all damage the ferrite core."
which means these dyno folks font let me fiddle much with their pickup and increases my burden to get it right the very first instance!
One othe option is to get hold of a motorcycle which is right now not possible for me atleast not it a lab environment where I can connect things!
Ferrite cores are not so hard to handle, but they can be broken after tight mounting by e.g. vibrations. Shock absorbers IMO can reduce that risk.
Simulation of an inductive pickup can be hard. You should at least know the peak voltage of the connected sensor and the impedance of the input. Testing may be possible with a rectangle signal of variable amplitude, e.g. from an op amp with a high supply voltage (+-15V) and a pot for setting the amplitude. Capacitors can be used to feed that signal into the input, but their capacity must be sufficient for driving the device input.
Eventually a switched coil can be used to simulate the signal, but the switching device and the coil must support the voltage spikes created when the current is turned off.
"Inductive pickups are very fragile. The ferrite core can easily be damaged and is not covered under warranty. Dropping, snapping, vibration, and heat can all damage the ferrite core."
This is the type of pickup they are talking about, it is not a ring, but a U and I core, the material they are made of is very brittle, and when I use to supply them, I would suggest to the customer to make a cushioned condom around it so it wouldn't melt or rattle against the engine.
The signal is basically about 2 to 5v spikes, the input circuitry has some very hardy over voltage protection in case of ignition lead flash over to the pickup.
A 5V square wave fed through a 0.1uF capacitor should be sufficient to provide a similar signal.
Do I follow correctly?
In principle, you are attempting to induce electrical signals into the Dyno Jet 250i so that it behaves as though there was a motor cycle under test, and that you can vary the simulated engine speed with your proposed microcontoller based device ?
Are you attempting to do this non-invasively, ie inducing a signal into the existing pickup sensors, or are you going to emulate the output of the pickup sensors and feed this signal by a direct electrical connection into the Dyno Jet 250i ?
6v6gt:
Do I follow correctly?
In principle, you are attempting to induce electrical signals into the Dyno Jet 250i so that it behaves as though there was a motor cycle under test, and that you can vary the simulated engine speed with your proposed microcontoller based device ?
Are you attempting to do this non-invasively, ie inducing a signal into the existing pickup sensors, or are you going to emulate the output of the pickup sensors and feed this signal by a direct electrical connection into the Dyno Jet 250i ?
Emulating is the safest, unless you want to setup an ignition coil, spark plug, battery an el-cheapo electronic ignition and a LM555 in Astable mode and a pot.
Tom...
Just an LM555 and a cap will provide the needed direct signal.
TomGeorge:
Emulating is the safest, unless you want to setup an ignition coil, spark plug, battery an el-cheapo electronic ignition and a LM555 in Astable mode and a pot.
Tom...
Just an LM555 and a cap will provide the needed direct signal.
I agree that it would be significantly easier to directly inject a signal into the Dyno Jet 250i device, once the nature of that signal had been determined and a suitable connector found, but rigging an ignition coil, ignition lead and sparkplug to an arduino would also not be too difficult ( mosfet, flyback diode,12v power supply and little else). I don't believe an electronic ignition is a requirement for this test, but I skimmed the manual only for a few minutes.
If the OP is concerned about physical damage to the delicate sensors as his first post suggested, he should be equally concerned about damaging the entire Dyno Jet 250i through some wiring error or such like.
6v6gt:
Do I follow correctly?
In principle, you are attempting to induce electrical signals into the Dyno Jet 250i so that it behaves as though there was a motor cycle under test, and that you can vary the simulated engine speed with your proposed microcontoller based device ?
Yes, we are on the same page!
6v6gt:
Are you attempting to do this non-invasively, ie inducing a signal into the existing pickup sensors, or are you going to emulate the output of the pickup sensors and feed this signal by a direct electrical connection into the Dyno Jet 250i ?
It's non-invasive, in the sense that I just am going to use the existential pickup line on the dyno250i and then feed it a signal from microcontroller.
TomGeorge:
Hi,
This is the type of pickup they are talking about, it is not a ring, but a U and I core, the material they are made of is very brittle, and when I use to supply them, I would suggest to the customer to make a cushioned condom around it so it wouldn't melt or rattle against the engine.
The signal is basically about 2 to 5v spikes, the input circuitry has some very hardy over voltage protection in case of ignition lead flash over to the pickup.
A 5V square wave fed through a 0.1uF capacitor should be sufficient to provide a similar signal.
Tom...
You have proven, the condoms are life savers!
let's say I have to emulate 100rpm, in that case what should be the frequency of the signal!?
GoForSmoke:
I think that Tom has experience with these sorts of things.
DSP would be more expensive and likely require a lot more work.
Nish, are you tired, are you working really long days? 100 revs per minute is how many revs per second?
Haha, Neal, Not really but yes I'm stressed from work! ,With the frequency I meant that are the 100 rpm's proportionate to a 100hz pwm signal frequency !?
Edit: Ya Neal, My days are hella long! coming back home by 11 at night starting the day @ 9, i'll PM u for more!
GoForSmoke:
Hz (Hertz) are cycles per second. RPM is cycles per minute. Hz = PRM * 60.
I think you need a miso soup and some hours of rest.
LoL I think you misunderstood me, I'm talking about the PWM signal frequency that I will need to feed into the RPM pickup or else how does the pickup know its what RPM!?
You send a square wave, not PWM. Eventually sound() may do the trick, depending on the required frequency. Or you program a timer for the right output frequency.
DrDiettrich:
You send a square wave, not PWM. Eventually sound() may do the trick, depending on the required frequency. Or you program a timer for the right output frequency.
Well a PWM wave with a 50% duty cycle is an ideal square wave.
Thanks for telling me about sound method ,Ill try that.
I think frequency modulation turns out as a rpm output. I would. nevertheless, have to try that! (I'm going to the dyno tomorrow so any heads up and information is appreciated and as always Thanks a lot for being there!)
Nishant_Sood:
LoL I think you misunderstood me, I'm talking about the PWM signal frequency that I will need to feed into the RPM pickup or else how does the pickup know its what RPM!?
I think it's circuit and bit bang time, you gotta mess with clocks to get a PWM faster than default.
Hi,
The inductive tacho clamp fits on one of the spark plug leads.
2 Stroke .. 1 revolution per Cyl Ignition pulse.
4 Stroke .. 2 revolution per Cyl Ignition pulse.
