JeffHs
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| posted on 29/6/09 at 12:19 PM |
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Digital Revcounter
Is there a cheap and cheerful way of counting revs on a propellor? I want something, strictly for ground running, to calibrate a refurbed rev counter
on the Auster. At the moment we know our tacho is way out. so we can't do our ground running schedules.
It's a 2 bladed ali prop, rev range 500 to 2700.
Jeff
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matt_claydon
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| posted on 29/6/09 at 12:31 PM |
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Google "Optical Tachometer" and you should find all you need, including circuits to build your own.
Or just use a cheap multimeter with tacho function conected to the coil on the engine. Google "Automotive multimeter" or similar.
[Edited on 29/6/09 by matt_claydon]
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procomp
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| posted on 29/6/09 at 12:49 PM |
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Hi
Just buy a cheap tacho meter. Comes with shiny sticky tape that you place on prop Etc. And point meter at it gives digital read out. Use one on the
lathe and drill when wanting to quickly see rpm ect also good for checking engine rpm and they are quite accurate. Price well some are £100 + but some
are £30ish.
Cheers Matt
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rf900rush
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| posted on 29/6/09 at 01:50 PM |
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Try one for Model RC planes.
Got a cheap tacho a few years back.
Also allows for 2,3 and 4 blade props.
Linky
Martin
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BenB
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| posted on 29/6/09 at 03:33 PM |
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I probably wouldn't go for the model tacho which you have to hold against the nosecone 
but you can buy optical tachos off ebay for 20 quid (stick a reflective strip on the prop and voila).
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BenB
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| posted on 29/6/09 at 03:36 PM |
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I got this one:
£15 from Ebay (inc P+P)
Only downside is the rubbish instructions: (so funny I scanned them!!)
 
Crazy tacho instructions
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JeffHs
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| posted on 29/6/09 at 04:34 PM |
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Brilliant. I suspect English isn't his first language.
Tacho looks like a bargain. I just need to find someone to hold it within 20 inches of the prop. Not even I'm daft enough to try that!
Seriously though - thanks for all the tips. We're going to try borrowing a professional device from the University Engineering Dept
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britishtrident
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| posted on 29/6/09 at 06:07 PM |
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Other way would be a Oscilloscope --- presume you have magneto ignition so inductive pickup off a plug lead.
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