RPM "Danger Band" warning device?

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cardiffrob
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RPM "Danger Band" warning device?

Post by cardiffrob » Sat Dec 27, 2014 3:24 pm

Are there any electrickery people here?

I have a little problem with an old Austin Seven which is an ideal tow car for a small homebuilt since nobody will expect it to go very fast, with or without an aeroplane on the back. Our Morris is being rebuilt and won't have a towbar on it once finished.

On the old 1930s Austin engines they have a nasty habit of divesting themselves of crankshaft journals if the engine is permitted to wallow in the 2200 to 2400 rpm band for very long. I was wondering if some kind soul could suggest a method of making a simple warning 'gadget' to light up a bulb if the car sat in that band of speeds. Is it a simple job or would it take some expensive kit to make?

I'm a bit of a dunce on anything utilising electrons, a bit like Mr Lucas was.

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G.Dawes
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Re: RPM "Danger Band" warning device?

Post by G.Dawes » Sun Dec 28, 2014 9:01 pm

Borrow a rev counter (Loads of people have them in the cupboard from years ago) that run off the ignition couple it go to the speed it is in the band and mark the speedo for the two higher gears then avoid the speeds. I didnt know it went that high let alone in top.
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tnowak
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Re: RPM "Danger Band" warning device?

Post by tnowak » Tue Dec 30, 2014 8:42 am

Hi Rob,

As Graham suggested, the simplest solution would be to use some kind of tacho which detected engine speed using ignition pickup.
Google for this:
"Spark Plugs Engine Digital Tach Hour Meter Tachometer Gauge Motorcycle ATV".
Amazon and EBay appear to have them available (or something similar).

To try and make something that lit up a bulb for a specific RPM band would take quite a bit of effort and a lot of messing about, unless you were an electronics hobbyist and happy to experiment with circuit design.
Tony
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Chris Martyr
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Re: RPM "Danger Band" warning device?

Post by Chris Martyr » Tue Dec 30, 2014 9:25 am

Well spotted Tony !
I certainly agree that having a tach is better than a warning light type device, and being so small and light means you can Velcro it out of sight when not required , and at £6.46 on Amazon with free postage , you can always use it for something else if it isn't suitable .

As for Rob's picture, fabulous , what a damn fine equipage ! looks like something straight out of PFA's archive . Can I request that you post one with the A7 towing FRED as well ? :D
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ColinC
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Re: RPM "Danger Band" warning device?

Post by ColinC » Tue Dec 30, 2014 9:51 am

Hi,

Quasar electronics do an electronic tachometer kit:

https://www.quasarelectronics.co.uk/Ite ... -indicator

You could build one of those and simply add extra red LEDs in the band to avoid perhaps, or mount that band of LEDs remotely? The kit is not cheap but probably better than trying to make your own boards and buying components.

Alternatively, it might be possible to canniblise one the cheap led tachos sold on ebay and do a similar thing?

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Colin
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mikehallam
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Re: RPM "Danger Band" warning device?

Post by mikehallam » Tue Dec 30, 2014 2:14 pm

Or something like this - under a tenner delivered.

http://www.banggood.com/2-inch-52mm-Blu ... 89746.html?

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cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Wed Dec 31, 2014 11:16 am

Thanks guys.

Colin might have given me an idea that could solve the problem.

I've avoided the use of a normal revcounter since with no synchro, cable brakes etc it is easy to neglect the revs, hence the idea of using a light. I shall look around for an LED revcounter and see if I can splice in some larger bulbs that illuminate at the right point. I have one of those Tiny Tach revcounters on the FRED but it is quite hard to see and still only tell me what I want to know if I am staring right at it.

I'll let you all know how I get on.

Ta

Rob
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cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Wed Dec 31, 2014 11:33 am

Image

Not quite finished, yet.

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Chris Martyr
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Re: RPM "Danger Band" warning device?

Post by Chris Martyr » Wed Dec 31, 2014 5:23 pm

An Austin 7 Special, brilliant ! As a fellow classic car buff I've always fancied one of them, my dad used to be a member of the 750MC .
I think that Brian should commission an article for LA mag with FRED and his fantastic tow-car .

Thanks for that Rob, it's made my day .
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cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Sun Jan 04, 2015 10:20 am

Thanks, Chris.

Anyway, I've ordered an Arduino computer kit since they can be made to run all the items I've been thinking about and can also display temperatures and pressures through the same cheap device. I need to learn how to 'code' it but it seems simple enough.

Details to follow, albeit not for a while.

PS FRED can go backwards down a motorway faster than it can fly forwards. Is there any other aircraft able to potentially exceed Vne in reverse???
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cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Sun Jan 25, 2015 2:10 pm

Image


Version 1 up for testing. It will display Rpm, oil pressure and water temperature whilst also setting off some big LEDs if anything goes outside of the required parameters. Less than £50.
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cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Sun Jan 25, 2015 2:19 pm

They make 'modules' for GPS, compass, 3D accelerometers , air pressure comparison (ASI/Pitot), air temp/humidity (carb icing) and many more, all for very low prices. It is a wonder that nobody has developed a mini SSDR IFR EFIS display!
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Nick Allen
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Re: RPM "Danger Band" warning device?

Post by Nick Allen » Mon Jan 26, 2015 3:43 pm

Cool! Have you got any useful website links for us?

cardiffrob
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Re: RPM "Danger Band" warning device?

Post by cardiffrob » Mon Jan 26, 2015 10:37 pm

Nick. Type "Arduino" and practically anything else into google and you'll find someone using one to run just about everything you can imagine. http://playground.arduino.cc/Projects/Ideas



Basic board on Ebay is below £5 so it doesn't break the bank if it were to go "Pfhut".
I've just started looking at OLED TV screens for a display that would suit an EFIS-style dashboard. A bit of a leap from where I am at the moment but 3 weeks ago I couldn't even work a mobile phone! The other direction I would like to try is to map a simple ignition curve and match the rpm to the amount of time after a certain point that the ignition triggers the coil to fire a spark (a.k.a. a Leburg clone)
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ColinC
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Re: RPM "Danger Band" warning device?

Post by ColinC » Tue Jan 27, 2015 10:19 pm

Seems like there's an amazing array of sensors and add on boards for the Arduino available for just a few pounds. I have ordered a few parts to assemble a compass/DI type instrument just to see how it all works. I have one of those vertical card compasses that could be driven by a stepper motor perhaps more reliably than the existing mechanical mechanism which might be interesting.

There's certainly the potential to exploit these and the computer on a board Raspberry Pi devices to develop useful devices. For example, a lift reserve indicator using pressure sensor boards could be done for a few pounds of money and a few ounces of weight.

Regards,

Colin
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