Recommend me a rev counter

[Graham_Wright]

I would like an analogue rev counter that takes its information from a crankshaft sensor as opposed to sensing alternator output.
Does such a thing exist?
Ebay searches have not revealed one.
Digital display ones exist (I have one somewhere if only I could find it!).

 

[scottie]

I would like an analogue rev counter that takes its information from a crankshaft sensor as opposed to sensing alternator output.
Does such a thing exist?
Ebay searches have not reveled one.
Digital display ones exist (I have one somewhere if only I could find it!).

Why ?

Are you reinventing the wheel?

 

[Graham_Wright]

Why ?

Are you reinventing the wheel?

Because it is a better engineering solution.
The one I have currently reads correctly at 400 rpm but progressively under reads at higher revs. Why? Belts slippage maybe or a defective gauge which can only be adjusted for one speed.
Sensing from an inductive or optical mark on the rankshaft seems much more elegant.

 

[Refueler]

You answered it yourself - optical ....

I have hand-held - but I'm sure there must be a mounted one ? But of course you also want Analogue dial .... mmm apart from pulsed alternator sensor ???

 

[ChromeDome]

For diesel engines you get a unit that sense the injections by being clamped onto an injector pipe.

One, albeit digital, is the Tiny Tach

 

[Plum]

I would like an analogue rev counter that takes its information from a crankshaft sensor as opposed to sensing alternator output.
Does such a thing exist?
Ebay searches have not revealed one.
Digital display ones exist (I have one somewhere if only I could find it!).

I have not seen an analogue one that uses a crank sensor. I fitted a Durite one 13 years ago and is still perfect. https://www.durite.co.uk/durite-sho...-dial-12-2/052530-led-illuminated-marine.html. (latest model, looks identical). Which uses the alternator connection. It has a calibration adjuster which I set at cruising revs using a RPM app on my phone which gave me accuracy over the rev range within the resolution of the dial so, for me, no benefit of a crank sensor.

 

[ChromeDome]

Several analogue sensor types available (crank or any other spinning part), -even wireless!

One on Amz

 

[Graham_Wright]

Several analogue sensor types available (crank or any other spinning part), -even wireless!

One on Amz

But there is no reference to a sensor. The output from an alternator er alternsates - probably a sine wave.
Outputs from pulse sensors are square wave (or sawtooth). With an engineering background, I would hope the interface would be defined.
The Amazon entries are typically Chinese with adulation and repetition.

 

[lustyd]

Why ?

Are you reinventing the wheel?

Victron B2B interferes with the RPM signal on some installations so sometimes the traditional methods fail.

 

[PaulRainbow]

But there is no reference to a sensor. The output from an alternator er alternsates - probably a sine wave.
Outputs from pulse sensors are square wave (or sawtooth). With an engineering background, I would hope the interface would be defined.
The Amazon entries are typically Chinese with adulation and repetition.

VDO make analogue tachos that work from a sensor. I have 4 here, 2 at each helm, the sensors aren't cheap though.

I have just replaced the 2 at the lower helm with KUS tachos, these work with the engine sensors or tachos. I have spare VDO gauges, but they are 24v.

See KUS Tachometer Gauge 3000 RPM with Hourmeter (Black) But i bought mine on Ali Express.

 

[ChromeDome]

But there is no reference to a sensor. The output from an alternator er alternsates - probably a sine wave.
Outputs from pulse sensors are square wave (or sawtooth). With an engineering background, I would hope the interface would be defined.
The Amazon entries are typically Chinese with adulation and repetition.

In many cases sensors are referenced in detail. The one I randomly linked to has a description:

Tachometer Sensor Model: M18 x 1.5 / M16 x 1.5

Operating Current: ≤60MA
Operating Voltage: 12V / 24
Range: 0-3KRPM
Input Signal: Additional signal from tachometer sensor, engine, alternator, ignition coil, crankshaft sensor, etc.

If you order a kit with (e.g. NPN-) sensor etc. there should be no compatibility issues. Autometer offers a pickup to fit on the alternator outside, which works with many brands if you don't want their gauge.

In cases where the original signal source can not be found/fixed easily, a replacement seems tempting. Especially if at a fraction of the cost.

 

[ChromeDome]

VDO make analogue tachos that work from a sensor. I have 4 here, 2 at each helm, the sensors aren't cheap though.

I have just replaced the 2 at the lower helm with KUS tachos, these work with the engine sensors or tachos. I have spare VDO gauges, but they are 24v.

See KUS Tachometer Gauge 3000 RPM with Hourmeter (Black) But i bought mine on Ali Express.

When KUS state "engine signal" do they mean alternator W-terminal to send the Wave frequency?

 

[Refueler]

I have this on Superanne :

Sensor

Diesel Engine Tacho Adapter RPM Signal Sensor Fit For Vehicle Truck Boat Yacht | eBay

Gauge

2" 52mm Tachometer 0-4000rpm Tacho RPM Gauge For Marine Boat Car Waterproof | eBay

I have another ready to fit to Anisette.

I have a hand held tacho that I have checked the above against - and its good enough .. well within reasonable tolerance. So simple to fit and setup. Took all of about 20mins incl calibrating.

 

[PaulRainbow]

When KUS state "engine signal" do they mean alternator W-terminal to send the Wave frequency?

Sorry, post #10 should have said "engine sensors or alternators", not "engine sensors or tachos".

The ones i have do work with either, i tested that when i fitted them.