X-Authentication-Warning:	delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient:	geda-user AT delorie DOT com
X-Injected-Via-Gmane:	http://gmane.org/
To:	geda-user AT delorie DOT com
From:	Kai-Martin Knaak <knaak AT iqo DOT uni-hannover DOT de>
Subject:	Re: [geda-user] Best way to measure RPMs
Date:	Thu, 23 Jan 2014 00:06:59 +0100
Organization:	Institut =?UTF-8?B?ZsO8cg==?= Quantenoptik
Lines:	18
Message-ID:	<lbpiu7$26i$1@ger.gmane.org>
References:	<CALSZ9gp+idKpy7gfgsUXry0tnQ--bSLjkSURMiNPEzXids8o8g AT mail DOT gmail DOT com> <CACPio-6AquQDoMBxwOFTWdxdhQCe0OZWwzu5EvmcWFu4sqOZyg AT mail DOT gmail DOT com> <CALSZ9gpRgtDUnnvHVGY8zLdWNrAiaEUb5gM3va8vTSbfc+Dr6A AT mail DOT gmail DOT com>
Mime-Version:	1.0
X-Complaints-To:	usenet AT ger DOT gmane DOT org
X-Gmane-NNTP-Posting-Host:	bibo.iqo.uni-hannover.de
User-Agent:	KNode/4.11.3
Reply-To:	geda-user AT delorie DOT com

Rob Butts wrote:

> The application is an arm bicycle where the spinning shaft is connected
> to a handle on each end so with no gearing the rpms will not be too
> high.  I don't have any encoder yet and I can attach anything to the
> shaft.

There is a spinning top experiment in the physics lab at my day job. We 
attach a little magnet to the wheel and put a pick-up coil from an 
electrical guitar in the sensor. A comparator turns the signal from the 
coil into TTL compatible form. This gets fed to a digital multimeter with 
frequency input.

The set-up works nicely from up to 3 cm distance. And it proved to be 
student safe since 3 semesters :-)

---<)kaimartin(>---    

- Raw text -