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Motorcycle RPM switch

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Hi All,

1st off - audioguru -- LOL LOL LOL :D You're madder than a bucket of spiders - I like it

If you want to live in the UK to Know aout Big Brother watching you behind the wheel. Fixed speed cameras on almost every primary road, dynamically adaptable speed cameras on motorways. There's now talk of RF & GPS in new cars to monitor and log where and when you drive.
If you get from A to B in a certain time your nicked, it is going to be marketed as congestion charges with automatic billing - yeah right

2nd for mattpatt

My aplogies to mattpatt - I was a bit harsh - I have re-read the post and he (she) did say they where new to electronics, the manners thing i'll stick by!

3rd - My Block Diagram

My thought process was running on black coffee at the time (the genuine filter stuff not instant) I think the Frequency multiplier might possibly have been a bit of a mistake :oops: :oops: :oops:

Charge Pumps are not the most reliable things in the world, And without some testing I'm not sure if it would be needed. But if it were, then eblc1388 has probably nailed the solution but, in my opinion, to get reproducable accuracy someform of divider/crystal based oscillator should be used again component tolerences would come into play
With hindsight I dont think an increase in frequency (over the ignition pulses) is called for.

4th for Ron h

In a caffeine induced stupper my thought process for the circuit operation was as follows

How to get a digital word (from the ignition) with which to compare a fixed preset (but alterable) value.

How can this word represent ever changing values (ignition pulses)

I originally thought about counting the pulses in a given time but then quickly realised it was not a time based value which was required but an actual numeric number based on the number of pulses received.

How could I stop the counter continously increasing the count to give a false positive condition. Thats where the bit on the right hand side of the diagrm comes in to play. By comparing the same D(n) pins from the counter but separated by a small time gap it would be possible to differentiate increasing and decreasing revs - so as to stop the counter counting up all the time If the revs were increasn the count would increase, if the revs decreased so would the counter and if the revs where constant so the count would not count (but hold its value) -'a closed loop'
This was to be done probably using a couple of LSB off the counter via a bit of logic (using a basic sample and hold idea)

If 4585 comparators were used they have the necessary logic to show >,= and < so if the 'greater than' pins used for the LED it would be continuously lit if the revs kept increasing as opposed to a quick pulse.

Incidently, I have just found a circuit based on four Op-Amps to sequentially switch four relays on an increasing input voltage - which I thought would be very suitable if mattpatt continued with the 2917 circuit he could have warning if potentiol DOOOOM before his engine explodes :)

PM me if you want it published on the forum

Dotnet
 
Hi Dotnet,

Instead of using magnitude comparator, I would suggest using a 64KB UVEPROM which has 16 address lines. Just program the corresponding data bit to become high or low according to the address.

One can have 8 independant speed setting this way. If that's not enough, use decoder to decode the 8-bit binary data to get as many as one like.

So in a netshell, signal input shaping and then feed to toggle flip/flop. Output of F/F use to gate a fast clock into a 16-bit counter with output latch. Counter outputs to address line of 27C512 and eight data output LEDs to indicate speed.
 
Hi eblc1388

Yes, I agree that would make sense to use an EPROM it would certainly cut down on the soldering! :)

If you read the posts we have all agreed a better method would be to use a MCU - but the same problem would arise as with using an EPROM you have to phisically unplug the thing to re-program it

But may I please remind you -my cricuit idea was BRAINSTORMING exercise not a design exercise. It was just my way of solving a problem which answered a lot of issues, would teach the guy something about binary and would be a really satisfying little project for him to develop and build. If things didn't work as expected it could be easily found with a logic probe or similar. It could be built on veroboard and leave the constructor with a great sense of achievement when completed.

It served a purpose and was my little way of getting someone to think out of the box.

I fully appreciate there are better ways of doing what I have proposed, it was just my way whilst I was skiveing.

Dotnet
 
Dotnet said:
If you want to live in the UK to Know aout Big Brother watching you behind the wheel. Fixed speed cameras on almost every primary road
I got caught speeding by a radar camera. I think my turbo's wastegate got stuck so I let the car wind up instead of turning it off (it's hard to steer with the steering locked).
I went to the cops' headquarters and got a copy of a huge colour pic of the entire road. I took it to court and showed it to the judge and asked, "Your honour, many cars are shown in that pic, one is mine, which car is speeding?"
Case dismissed. :lol: :lol:

Now they have laser cameras and I guess the laser's dot is shown burning a hole in the speeding driver's neck. :cry:
 
Hey Audioguru,

Our road traffic bas***ds have that one sussed, we have fixed cameras that take two photos against lines painted on the road spaced about a metre apart
The idea is one backs up the other and it is also possible the check the calibration because the the two takes are very precisely timed
(speed =distance/time)

I'm afraid when the photo lands on your carpet one rainy morning there is absolutly nothing you can do about it

Well I say nothing for it to be a valid conviction both photos of your car have to be over the white lines. A recent car TV program demonstrated (on a runway) that if you travel at 170 MPH only one photo can be taken in the 'danger zone' so in theory you're safe.

I tell you mate, we are so busy looking for f***ing cameras we have accidents, it wouldn't be so bad if they stuck'em outside schools or in towns

Count yourself lucky
Dotnet
 
To everyone,

I thank you all for your help on this subject, and I didn't mean to be rude to anyone. I apologise if it seems that way.

The thing is that I am trying to run my own business in Thailand and these last couple of weeks have been seriously hectic. Chasing suppliers and meetings with distributors and customers. This is the first chance that I've had to really get back into this, and to be honest I'm just grabbing a couple of minutes now as I feel rather bad! :oops:

I'll have another good read through this thread toninght when I can knock off and we'll see where we are.
 
Thanks for being patient.

I tried following the speed switch schematic from the NSC data sheet, with a couple of things thrown in from the previous schematic of the commercial unit and it doesn't do as it's told.

I've had another mess around since I scribbled the sketch.

The 100K variable resistor is now a 1M. Pin 8 now goes through a BC337 transistor as in the previous schematic.

With this setup the LED is lit all the time. If I adjust the 1M VR the voltage on pin 3 doesn't change. It should do as I tested backto back with the commercial unit. I'm confused.

It's not so much that I want to go one better than what's available, it's got to the point where I just want to try and understand what's going on!

If I can get the voltage to vary at pin 3 then i think I'm sorted.

Oh, and many apologies for the useless drawing. I see that I've forgotten to draw the earth bit in after the zener attached to the frequency in line. I'll have another go and see if I can do one a bit more up to date and complete.
 

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A quick message to Dotnet.

I appreciate the hard work involved in your reply to me. I'm a real novice at this game so I'm looking for something simple. I can't even get a grasp of the so called simple stuff! :oops:
 
Hi Matt,
Doyou have breaker points or a variable-reluctance pickup?
On either method, pin 1 needs a resistor to ground to provide its 0V reference.

With breaker points, it would probably work OK if you also add the necessary resistor and diode to pin 11 so that the input has a reference voltage. Then of course the 5k resistor would need to be connected to ground instead of to pin 11. :lol:
 

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I edited my recent sketch that showed the zener diode inside an LM2917.
 
Thanks audioguru. I'll give that a try later on this morning and see what happens.

I'm using a variable-reluctance pickup at the moment. It's just something that I knocked up to provide a signal.

I'd like to be able to have an rpm range of up to 14,000 rpm, or there abouts. Typical settings for my shift light application would be between 11,000rpm and 13,000 rpm. However, I have many plans for this type of switch, pretty much all related to motorcycles, with various switch on points.
 
I think this circuit is what i need. I also need some help regarding the VR settings. I want a circuit to close a switch (Relay 1 NO terminals) when the input detects a preset RPM.

Am I correct that if i select LK1 to L/H position, the relay will be energized if pin8 of IC1 is high? How will i adjust VR1 and VR2 so the relay will be energized if input at pin1 is above 10Khz?
 
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