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=B0SG7dh64MCKA7G0+w/5o8JVhR8HKsLygMRwxMhR0jw=; b=OGMXcijHDFICVyZ7AGUn0i7XJPr/BsZyvIMKTgpCCSJzxzCwXE0xqFsvha33B63UY3 uSurmr47Ecg4avoWGaFijCCmVryZZaLtRF16GZW5TISw4fgLshG93gpFHpNp974tJozS DJs4UJJ/uYPfFOgFxgQE/Y505Y0B9VAx+fPYc5OYt2w9pJuPx644pTpTRrpfXeOKA5N8 Uyz4UtccT3kGOGd27MfGb/2ELF3mN/8R4IlajUnmvBLLqBwQCAmk3/M8Ucb9xoEwE9Zq 744zTZ9TWZfu3CfACXkiqNNRjIt3xi716Gs39N0NaP68N2T8Vs0lAuhpXzYsLXO3Ai9+ HBnA== MIME-Version: 1.0 X-Received: by 10.180.93.196 with SMTP id cw4mr284616wib.39.1390502556647; Thu, 23 Jan 2014 10:42:36 -0800 (PST) In-Reply-To: <0b0750d2097334a10a9c03e2f9b09599@mail.gmail.com> References: <52E02A51 DOT 5090008 AT estechnical DOT co DOT uk> <0b0750d2097334a10a9c03e2f9b09599 AT mail DOT gmail DOT com> Date: Thu, 23 Jan 2014 13:42:36 -0500 Message-ID: Subject: Re: [geda-user] Best way to measure RPMs From: Nathan Stewart To: "geda-user AT delorie DOT com" Content-Type: multipart/alternative; boundary=f46d0438932bf2c68504f0a79a64 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 --f46d0438932bf2c68504f0a79a64 Content-Type: text/plain; charset=ISO-8859-1 What I had in mind given the ferrous gear ring was something like Cherry's VN101501, but it's pricier than I expected ($7.22/qty 1). It requires a fixed permanent magnet on the other side of the gear tooth from the sensor. A photo interrupter like Sharp GP1S58VJ100F is $0.93/qty 1 from DigiKey, but typical current draw on the LED is 10-20mA. Not huge, particularly if you're contributing to the electrical power generation, but enough to make batteries a nuisance. (And if you a running a generator off that crank, then there ya go - you already have your sensor elements built in.) On Thu, Jan 23, 2014 at 9:33 AM, Dave Kerber < dkerber AT warrenrogersassociates DOT com> wrote: > I can hit 120 or slightly more with my legs and a light load, so I expect > I could go higher with my arms. That's with a shorter radius, though; > 170mm crank arms. I'd bet that if you allow up to 120-150rpm, you should > be able to handle all but the most extreme cases. > > > > > -----Original Message----- > > From: Rob Butts [mailto:r DOT butts2 AT gmail DOT com] > > Sent: Wednesday, January 22, 2014 3:51 PM > > To: geda-user AT delorie DOT com > > Subject: Re: [geda-user] Best way to measure RPMs > > > > 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 > > 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 > > > > > > > > > > > > > --f46d0438932bf2c68504f0a79a64 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
What I had in mind given the ferrous gear ring was so= mething like Cherry's VN101501, but it's pricier than I expected ($= 7.22/qty 1). It requires a fixed permanent magnet on the other side of the = gear tooth from the sensor.

A photo interrupter like Sharp GP1S58VJ100F is $0.93/qty 1 from D= igiKey, but typical current draw on the LED is 10-20mA. Not huge, particula= rly if you're contributing to the electrical power generation, but enou= gh to make batteries a nuisance. (And if you a running a generator off that= crank, then there ya go - you already have your sensor elements built in.)=


On Thu,= Jan 23, 2014 at 9:33 AM, Dave Kerber <dkerber AT warrenroge= rsassociates.com> wrote:
I can hit 120 or slightly more with my legs = and a light load, so I expect
I could go higher with my arms. =A0That's with a shorter radius, though= ;
170mm crank arms. =A0I'd bet that if you allow up to 120-150rpm, you sh= ould
be able to handle all but the most extreme cases.



> -----Original Message-----
> From: Rob Butts [mailto:r.butts2= @gmail.com]
> Sent: Wednesday, January= 22, 2014 3:51 PM
> To: geda-user AT delorie DOT com=
> Subject: Re: [geda-user] Best way to measure RPMs
>
> I was just looking at slot type photointerrupters. =A0I'd like
> to have the option to take advantage of resolution too. =A0They
> are cheap and I think will do what I need.
>
> The rpm range is a guess but 0 - maybe 60? =A0How 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&g= t; wrote:
>
>
> =A0 =A0 =A0 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.
>
> =A0 =A0 =A0 If you only care about single revs, stick a magnet on
> the shaft and have a reed switch to count revs.
>
> =A0 =A0 =A0 HTH,
>
> =A0 =A0 =A0 Ed
>
>
> =A0 =A0 =A0 On 22/01/14 20:23, Rob Butts wrote:
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 The application is an arm bicycle where th= e
> spinning shaft is connected to a handle on each end so with
> no gearing the rpms will not be too high. =A0I don't have any
> encoder yet and I can attach anything to the shaft.
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 On Wed, Jan 22, 2014 at 3:13 PM, Nathan St= ewart
> <therealnathanste= wart AT gmail DOT com> wrote:
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 That depends a lot on what= s 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.
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 What's the application= ?
>
>
>
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 On Wed, Jan 22, 2014 at 3:= 00 PM, Rob
> Butts <r DOT butts2 AT gmail DOT com= > wrote:
>
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 I have a s= haft that I want to
> measure the rpm of. =A0I'm looking for opinions on the best and > cheapest way. =A0The design is still in development phase so I
> have freedom.
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Thanks
>
>
>
>
>
>

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