Frequency 150-700Hz to Voltage?

[joza18]

Hello, I have a source (wire from cdi to coil) with 100-250VAC with frequency from 150 - 700Hz depending a rpm on my bike. Im trying to do something like a shift light with one turned LED on some rpms.

I tryed with LM2917 and several options, but it doesn work

Do you have a any suggestion please?

Thank you!

 

[4pyros]

Have you checked the biker forums?
I have seen many designs in them.

 

[joza18]

Yes I checked, but motorbikes have a different freq, like as petrol cars.
This shematic 100% work on honda integra and suzuki gsxr 600.

http://www.piergm.com/elettronica/spia_fuorigiri_schema.gif

But on my 2t single cylinder not working.

 

[4pyros]

How are you picking up your rev signal?
From the coil or crank sensor?

 

[audioguru]

The circuit you posted with the LM2907 tach IC does not work because the input (pin 1) of the LM2907 needs a DC path to ground, usually provided by a magnetic pickup.
Try the circuit after adding a 100k resistor from pin 1 to ground.

 

[eTech]

Hi

I can generate a simulation.
What is the desired frequency range and full scale voltage output?
Also, the number of engine cylinders and max RPM?
Also, what is the LED suppose to indicate?

eT

 

[joza18]

Thank you guys for interesting!! My test bike, have a 1 cyl, and 2 stroke engine. I want to LED lights at the desired speeds (rpm), usually between 6000-8000rpm.

I tryed to do about 10 versions. Here is a photo: http://www.dropbox.com/s/qf6q6yazhoczugb/20140529_093310.jpg

OK, now i will show you a service manual for bike, I tryed to take a signal from green wire primary (i tryed from pickup too): http://www.dropbox.com/s/cdtp9i3wpnantf6/Screenshot 2014-05-28 11.29.00.png

Here are other parts in ignition: http://www.dropbox.com/s/k20leosf38nb61w/Screenshot 2014-05-28 11.29.23.png


Here is a frequency result from green wire to ground, voltage is from ~150V - 200VAC
2000rpm - 150Hz
3000rpm - 250Hz
4000rpm - 330Hz
5000rpm - 450Hz
6000rpm - 500Hz
7000rpm - 600Hz
8000rpm - 700Hz
9000rpm - 1300Hz

And here is from pickup red wire to ground:
2000rpm - 380Hz
3000rpm - 530Hz
4000rpm - 750Hz
5000rpm - 950Hz
6000rpm - 1000Hz
7000rpm - 1200Hz
8000rpm - 1400Hz
9000rpm - 1530Hz

Voltage on 1800rpm is 0.7VAC, on 5000rpm is 1.5VAC, on 7000rpm is 1.9VAC, on 9200rpm is 2.3VAC.


And These are schemes by which I worked:

**broken link removed**

**broken link removed**

http://www.next.gr/automotive/automotive-circuits/overspeed-indicator-l12548.html

**broken link removed**

http://www.piergm.com/elettronica/shiftlight.htm




Now Im trying to do it this:
**broken link removed**

or this:
http://i134.photobucket.com/albums/q90/versamson/Tacho Project/pcb_lm2917.jpg

 

[audioguru]

Please attach your schematics to your posts HERE instead of over at UPLOADS where we cannot open or at PHOTOBUCK that takes a long time to open.
Did you try adding a resistor to ground on the pin 1 input of an 8-pins tach IC so that it has a 0V DC reference voltage? The other input is pin 8 which is connected to ground so its DC reference voltage is 0V.

 

[joza18]

Sorry, I didnt know that. Here is uploads...

Please attach your schematics to your posts HERE instead of over at UPLOADS where we cannot open or at PHOTOBUCK that takes a long time to open.
Did you try adding a resistor to ground on the pin 1 input of an 8-pins tach IC so that it has a 0V DC reference voltage? The other input is pin 8 which is connected to ground so its DC reference voltage is 0V.

I tryed with this, 2x 10k from input to ground.


Voltage on exit from lm2917 is same like on power supply (+12V), no changes. I know that voltage on exit must be variable, depending a freq on input.

 

[joza18]

Please attach your schematics to your posts HERE instead of over at UPLOADS where we cannot open or at PHOTOBUCK that takes a long time to open.
Did you try adding a resistor to ground on the pin 1 input of an 8-pins tach IC so that it has a 0V DC reference voltage? The other input is pin 8 which is connected to ground so its DC reference voltage is 0V.

Yes I tryed and nothing happen.


Today I worked with this schematic (IC is lm2917, 14pin version, a second diode (zener) is 1N4148):

Nothing happen again, 0V on out is always, but between input (ignition coil wire) and ground is 1.6V.
A source is motorbike, diesel car (alternator W signal), and transformer from 230VAC to 2.8VAC, 50Hz.

 

[audioguru]

Since you used an LM2917 IC in an 8-pins case, its 7.5V zener diode was blown up since you connected it to a 12V supply. The heat might have destroyed the IC.

The circuit layout posted in post #10 shows an arrow instead of a 1N4148 diode at its input. It also shows an arrow instead of a diode at pin 11. These diodes might be backwards.
Please post the schematic instead of the circuit layout.

 

[joza18]

I dont have a schematic from post #10, only this pic The guy made a tachometer with 20 leds on other forum, on Vout he merged to input a LM3914-->Leds.
My problem is 0V on output from lm2917.

 

[audioguru]

I do not know what are the voltage levels of the pulses from your ignition coil.
I do not know which end of the 1N4148 is the cathode since it is not the symbol for a diode. It seems to be backwards.
I do not know if the other diode is a zener diode and I do not know its voltage rating. Again I do not know which end is which.

 

[joza18]

I do not know what are the voltage levels of the pulses from your ignition coil.

From 150 to 200VAC.

I do not know which end of the 1N4148 is the cathode since it is not the symbol for a diode. It seems to be backwards.

I connect like this

I do not know if the other diode is a zener diode and I do not know its voltage rating. Again I do not know which end is which.

Both diode are 1N4148

 

[alec_t]

Both diode are zener diode, and both are 1N4148.

A 1N4148 is not a zener diode.

 

[audioguru]

From 150 to 200VAC.

Then you have destroyed the LM2917 because its datasheet says its maximum allowed input voltage is only +28V.
The diode at the top is connected backwards so it passes the high voltage to damage the input of the IC but it blocks a logic low so the IC will not work even if the voltage is reduced and the IC is replaced.

 

[joza18]

A 1N4148 is not a zener diode.

Sorry my bad, Im tired because Im trying to do it this about 3 weeks.

Then you have destroyed the LM2917 because its datasheet says its maximum allowed input voltage is only +28V.
The diode at the top is connected backwards so it passes the high voltage to damage the input of the IC but it blocks a logic low so the IC will not work even if the voltage is reduced and the IC is replaced.

Damn! I will buy a new one.


I have sa speedo sensor (digital speedometer) on my bike with hall effect (without intensity 1=0) 3 wire:
Positive +12VDC,
Negative -ground,
Signal wire.

Should I connect a lm2917 to that sensor? And wich one schematic is good for that sensor?
Thanks!

 

[audioguru]

The signal from your speedo hall effect sensor probably does not go below ground so the 8-pins versions of the LM2907 or LM2917 cannot be used.
One of your schematics has the reference input biased at +0.7V with a diode but the signal input is biased at +8.1V which is odd.

I think the reference input should be biased at half the supply voltage so then the sensor input can swing above and below it easily.

 

[eTech]

Hi

Here's something I threw together.
I'm still not sure what the OP wants for LED indication. Just light up between a certain voltage range?
Output is ~500mv per 1000 RPM

One image at 10000 RPM
One image stepped 1000 thru 10000 RPM

eT

 

[audioguru]

He is making a "shift light" that lights at a certain engine RPM when the gears should be shifted to avoid over-revving the engine.
The datasheet for the LM2907/LM2917 shows a "normal" engine application but the inputs are a magnetic variable reluctance pickup or breaker ignition points for car engines.