X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=n/E6wSCFIdMn08iAM5ql5p6z5Ma83Leeh1yD+ISPoCE=; b=VEJCN8XGbGTshdIAljf8shgqgOZhGtXT91vH0FOcYSGr2xM8+EE49fDVuAa8h4Lp7i AmcLJQzAYozaJCMxZcAVklwhALPRhi10sVOKxkR9W5NT1MWsbCgV074rycFFXWrFYvJJ shWtPQRmOkC7P4gLdepSllFwJ4WZU0NSk3BMijvTah5ZKf8pL6rZKSpa3NOp68bOFkd5 B1Pgb34zwSshNXlHWoP1iHNF/5EQaFR4rfXQOAA5EE2YOH7ZaJ9YfIQ5AwrAbGgubEa3 ZcjYQHv9IeR6flStDzt6/WV2hA9ecCFYHs7bFkYzt5AAddfA5XRPq4YCrSzsfiUcW3yK yP8Q== MIME-Version: 1.0 X-Received: by 10.43.61.196 with SMTP id wx4mr3045568icb.6.1390423874819; Wed, 22 Jan 2014 12:51:14 -0800 (PST) In-Reply-To: <52E02A51.5090008@estechnical.co.uk> References:

<52E02A51 DOT 5090008 AT estechnical DOT co DOT uk> Date: Wed, 22 Jan 2014 15:51:14 -0500 Message-ID: Subject: Re: [geda-user] Best way to measure RPMs From: Rob Butts To: geda-user AT delorie DOT com Content-Type: multipart/alternative; boundary=bcaec51dd1f125620004f0954924 Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk --bcaec51dd1f125620004f0954924 Content-Type: text/plain; charset=ISO-8859-1 I was just looking at slot type photointerrupters. I'd like to have the option to take advantage of resolution too. They are cheap and I think will do what I need. The rpm range is a guess but 0 - maybe 60? How fast can someone pedal a hand bike with roughly a 9" handle radius? On Wed, Jan 22, 2014 at 3:30 PM, Ed Simmons wrote: > Do you care about resolution within a revolution? Typically, for example > on the front wheel of a motor bike, you'd have a toothed wheel with one > missing tooth as an index pulse read by a hall effect sensor, equally > simple is doing the same thing with an optical setup. You can count > 'normal' pulses to get the resolution you need within an individual turn > and also look out for the longer pulse (or gap) caused by the index notch. > > If you only care about single revs, stick a magnet on the shaft and have a > reed switch to count revs. > > HTH, > > Ed > > > On 22/01/14 20:23, 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. > > > On Wed, Jan 22, 2014 at 3:13 PM, Nathan Stewart < > therealnathanstewart AT gmail DOT com> wrote: > >> That depends a lot on whats attached to the shaft, how fast it's >> turning, and what's driving it. Obvious solutions are encoder, interrupter >> (photo or magnetic - ic engines typically use an inductive pickup on gear >> teeth), or even counting pulses on the drive current. If you already have >> an encoder for other purposes, that makes a lot of sense. If you don't >> already have anything else that might work, interrupter and divide by is >> probably the most direct method. Sensing the driving forces can be a lot of >> things, from stepper motor pulses to spark plug firing. >> >> What's the application? >> >> >> >> >> On Wed, Jan 22, 2014 at 3:00 PM, Rob Butts wrote: >> >>> I have a shaft that I want to measure the rpm of. I'm looking for >>> opinions on the best and cheapest way. The design is still in development >>> phase so I have freedom. >>> >>> Thanks >>> >> >> > > --bcaec51dd1f125620004f0954924 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

I was just looking at slot type=A0photointerrupters.= =A0 I'd like to have the option=A0to take advantage of resolution too.= =A0 They are cheap and I think will do what I need.

=A0

The rpm range is a guess but 0 - maybe 60?=A0 How fast can someone pedal a= hand bike with roughly a 9" handle radius?

On Wed,= Jan 22, 2014 at 3:30 PM, Ed Simmons <ed AT estechnical DOT co DOT uk> wrote:

=20 =20 =20

Do you care about resolution within a revolution? Typically, for example on the front wheel of a motor bike, you'd have a toothed wheel with one missing tooth as an index pulse read by a hall effect sensor, equally simple is doing the same thing with an optical setup. You can count 'normal' pulses to get the resolution you need within an individual turn and also look out for the longer pulse (or gap) caused by the index notch.

If you only care about single revs, stick a magnet on the shaft and have a reed switch to count revs.

HTH,

Ed

On 22/01/14 20:23, 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.=A0 I don't have any enco= der yet and I can attach anything to the shaft.

On Wed, Jan 22, 2014 at 3:13 PM, Nathan Stewart <therealnathanstewart AT gmail DOT com> wrote:

That depends a lot on whats attached to the shaft, how fast it's turning, and what's driving it.=A0 Ob= vious solutions are encoder, interrupter (photo or magnetic - ic engines typically use an inductive pickup on gear teeth), or even counting pulses on the drive current. If you already have an encoder for other purposes, that makes a lot of sense. If you don't already have anythin= g else that might work, interrupter and divide by is probably the most direct method. Sensing the driving forces can be a lot of things,=A0 from stepper motor pulses to spark plug firing.

What's the application?

On Wed, Jan 22, 2014 at 3:00 PM, Rob Butts <r DOT butts2 AT gmail DOT com> wrote:

I have a shaft that I want to measure the rpm of.=A0 I'm looking for opinions on the be= st and cheapest way.=A0 The design is still in development phase so I have freedom.

=A0

Thanks

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