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Build or buy - mating old sensor to new display

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macorro

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Thought this might be an interesting first project, but my knowledge is very basic.

A 12v old (1988) boat speed indicator with its paddle wheel sensor. I have a new display which can read the old paddle wheel but interprets the speed at close to twice the proper value. Calibration on the new display is limited to about 15%. I guess the paddle wheel sends a signal each time a paddle induces a current.

I think if I can find a way to lose every other signal from the paddle wheel then I can use the two together. Such a circuit doesn't sound too complex - is this something I can buy? Otherwise could you give me some pointers, please?
 

BradtheRad

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A single flip-flop can be made to divide an incoming pulse train by 2.

A 'data' flip-flop is the customary type for this purpose. Connect one output to the D terminal.

http://www.electronics-tutorials.ws/counter/count_1.html

If you have a bunch of transistors, it should be possible to homebrew a flip-flop.
 

Warpspeed

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This could (?) be an analog system using tachogenerator and a voltmeter.
In which case, you need a potentiometer voltage divider to drop the indicated speed.

The flip flop is the right solution if its digital, the potentiometer if its analog.

How many wires going to the sensor ? That may be a clue.
 

macorro

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This could (?) be an analog system using tachogenerator and a voltmeter.
In which case, you need a potentiometer voltage divider to drop the indicated speed.

The flip flop is the right solution if its digital, the potentiometer if its analog.

How many wires going to the sensor ? That may be a clue.
The paddle wheel delivers has just 2 wires; I am picking up the signal from just one wire and which is all the new display requires.

Is this a well travelled path - can I buy the built circuit I need or do I need to build - I am pretty ignorant when it comes to this.

- - - Updated - - -

Thanks for the link. Is there a full schematic I could follow? - I will need to build from scratch or take a diagram to someone who can.
 

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