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Why are capstan wheels different size?
Oh, smarter-than-I people,
http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... |
Why are capstan wheels different size?
On 2016-03-11, DaveC wrote:
Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? do they have the same capstan diameter? -- \_(ツ)_ |
Why are capstan wheels different size?
M Philbrook wrote:
In article - september.org, says... Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Its been a while since I've seen the inside of a cassett drive. But memory tells me you have a pinch roller with pin shaft that governs the actual speed. Jamie Yep. -- Les Cargill |
Why are capstan wheels different size?
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Why are capstan wheels different size?
MJC wrote:
And I have long thought that with the small diameter of the capstan it must be the availability of excellent, and cheap, bearings for the shaft that made it possible to keep the wow and flutter down to acceptable levels... ** The vast majority use plain bearings and rely on a flywheel to do the rest. ..... Phil |
Why are capstan wheels different size?
Jasen Betts asked wisely:
do they have the same capstan diameter? I was just about to say €œSilly question!€ but instead thought better... one 2mm, one 2.2mm I guess the difference is driven (c; by the fact (stated by Phil) that the flywheels are different diameters to discourage mechanical resonance. Thanks Jasen! |
Why are capstan wheels different size?
On Fri, 11 Mar 2016 13:22:09 -0800, DaveC wrote:
Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Presumably the belt speed changes, or the capstains themselves are different diameters. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
Why are capstan wheels different size?
One (the small one) is the motor capstan.
The other one is the pressure capstan. Direction is given by the rotation of the first one and speed is servo-controlled. Generally there is a lever for the tension of the tape. DaveC a écrit : Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... |
Why are capstan wheels different size?
On Friday, March 11, 2016 at 1:22:14 PM UTC-8, DaveC wrote:
Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Looks like my Nakamichi cassette deck. They used 2 different sdiameter capstans / flywheels running at different RPMs BUT the same tape speed closed loop drive (both pinch rollers always engaged). They said they did that so that the capstans won't slowly go in and out of phase which causes wow and flutter to go up and down. By running different RPMs they go in and out of sync so quickly we don't notice it. As the belt stretches and contracts around the flywheels, the lead capstan will alway run slightly faster (tape speed wise) than the trailing capstan which keeps the tape tension correct on an auto reverse machine regardless of the direction. My deck is only single direction and the wow/flutter is nearly imperceptible. Then I went digital so who cares about cassettes? G² |
Why are capstan wheels different size?
Then I went digital so who cares about cassettes?
Need a source to digitize the analogue media... |
Why are capstan wheels different size?
On 12/03/16 08:42, wrote:
On Friday, March 11, 2016 at 1:22:14 PM UTC-8, DaveC wrote: Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Looks like my Nakamichi cassette deck. They used 2 different sdiameter capstans / flywheels running at different RPMs BUT the same tape speed closed loop drive (both pinch rollers always engaged). They said they did that so that the capstans won't slowly go in and out of phase which causes wow and flutter to go up and down. By running different RPMs they go in and out of sync so quickly we don't notice it. As the belt stretches and contracts around the flywheels, the lead capstan will alway run slightly faster (tape speed wise) than the trailing capstan which keeps the tape tension correct on an auto reverse machine regardless of the direction. My deck is only single direction and the wow/flutter is nearly imperceptible. I did initially think closed loop but then capstans would be revolving in opposite directions? It would be an extreme way to apply tension to a tape. -- Adrian C |
Why are capstan wheels different size?
On 3/12/2016 12:36 AM, Look165 wrote:
One (the small one) is the motor capstan. The other one is the pressure capstan. Direction is given by the rotation of the first one and speed is servo-controlled. Generally there is a lever for the tension of the tape. DaveC a écrit : Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... The tape speed is controlled by the motor drive capstan. Doesn't matter which way the tape is going. The two flywheels are different sizes, but have the same rotation speed. That causes the belt to stretch on one side and compress on the other to account for the different sizes. That belt tension creates the tape tension. That's independent of the direction of the rotation. Tape speed across the heads is always controlled by the drive motor. |
Why are capstan wheels different size?
On 12/03/2016 03:49, DaveC wrote:
Jasen Betts asked wisely: do they have the same capstan diameter? I was just about to say €œSilly question!€ but instead thought better... one 2mm, one 2.2mm I guess the difference is driven (c; by the fact (stated by Phil) that the flywheels are different diameters to discourage mechanical resonance. Thanks Jasen! May seem pedantic , but there is a rationale. Having been here before, to standardise to using a strobe to set tape speed, in the absence of a test tape of known goodness, ie not stretched, as the people wanting cassette players repaired these days tend to be musically on the ball as regards being perfect pitch. You'll probably find the spindle diameters are 1.99mm and 2.19mm . I got a precision mechanical engineer to measure a dozen or more random spindles and they were all *.*9 mm , presumably because the available bearings are *.*0 mm |
Why are capstan wheels different size?
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Why are capstan wheels different size?
Because of the thickness of the belt.
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Why are capstan wheels different size?
"I did initially think closed loop but then capstans would be revolving
in opposite directions? It would be an extreme way to apply tension to a tape. " Do you understand mechanics at all ? It helps. Those things are turning in OPPOSITE directions and therefore that deck is NOT a true dual capstan. It has two but the other one is used to regulate tapes speed in reverse. That is all. It does not have the the qualitative edge over a single capstan deck at all, that part of the mechanism simply facilitates the reverse function. It is not dual capstan at all. To me, and anyone who knows tape, dual capstan means they both work at the same time, and in that the deck, THEY DO NOT. It is either one or the other, depending on if it it is in the forward or reverse mode. At no time are both pinch rollers engaged. Only one at a time. When it's running look and see, and you will see. |
Why are capstan wheels different size?
Look165 wrote:
One (the small one) is the motor capstan. The other one is the pressure capstan. Direction is given by the rotation of the first one and speed is servo-controlled. Generally there is a lever for the tension of the tape. ** You on crack ?? |
Why are capstan wheels different size?
MJC wrote:
And I have long thought that with the small diameter of the capstan it must be the availability of excellent, and cheap, bearings for the shaft that made it possible to keep the wow and flutter down to acceptable levels... ** The vast majority use plain bearings and rely on a flywheel to do the rest. Sure, but my point was that any chatter in the bearings is just as bad as rotational variation and is not damped by the flywheel. So the plain bearings have to be accurate and long-lasting. ** You have completely forgotten the damping effect of side-ways pressure from the pinch roller. ..... Phil |
Why are capstan wheels different size?
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Why are capstan wheels different size?
wrote:
"I did initially think closed loop but then capstans would be revolving in opposite directions? It would be an extreme way to apply tension to a tape. " Do you understand mechanics at all ? It helps. Those things are turning in OPPOSITE directions ** Self evidently false. Yawnnnnnnnnnn................ .... Phil |
Why are capstan wheels different size?
On Friday, March 11, 2016 at 4:22:14 PM UTC-5, DaveC wrote:
Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... The capstan is a passive device. The motor pulley diameter via the *pinch roller* determines the tape speed. The capstan wheel can be any size at all. Peter Wieck Melrose Park, PA |
Why are capstan wheels different size?
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Why are capstan wheels different size?
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Why are capstan wheels different size?
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Why are capstan wheels different size?
On 11/03/2016 21:22, DaveC wrote:
Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Aiwa AD WX888 , 1997,I worked on once, spindle to one capstan 2.49mm diameter and the other 2.69mm |
Why are capstan wheels different size?
On Sat, 12 Mar 2016 17:37:50 +0000, N_Cook wrote:
On 11/03/2016 21:22, DaveC wrote: Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Aiwa AD WX888 , 1997,I worked on once, spindle to one capstan 2.49mm diameter and the other 2.69mm Aiwa ADR470, forward flywheel was inside the loop, reverse was outside the loop. Both always driven. choice of pinch rollers determine direction. Flywheel diameters compensate for inside/outside belt diameter. Only speed adjustment was screw-driver inside the motor housing itself. Harman Kardon HK300 had a single flyheel, spindle impressed alternately on fw or rev through a clutch that was always disintegrating. Same in-the-motor adgustment. RL |
Why are capstan wheels different size?
In article , says...
On 3/12/2016 12:36 AM, Look165 wrote: One (the small one) is the motor capstan. The other one is the pressure capstan. Direction is given by the rotation of the first one and speed is servo-controlled. Generally there is a lever for the tension of the tape. DaveC a écrit : Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... The tape speed is controlled by the motor drive capstan. Doesn't matter which way the tape is going. The two flywheels are different sizes, but have the same rotation speed. That causes the belt to stretch on one side and compress on the other to account for the different sizes. That belt tension creates the tape tension. That's independent of the direction of the rotation. Tape speed across the heads is always controlled by the drive motor. Really? Then what is the use of that little pinch roller and drive shaft that the tape fits between, for? Jamie |
Why are capstan wheels different size?
On Sat, 12 Mar 2016 13:06:27 -0500, legg wrote:
On Sat, 12 Mar 2016 17:37:50 +0000, N_Cook wrote: On 11/03/2016 21:22, DaveC wrote: Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Aiwa AD WX888 , 1997,I worked on once, spindle to one capstan 2.49mm diameter and the other 2.69mm Aiwa ADR470, forward flywheel was inside the loop, reverse was outside the loop. Both always driven. choice of pinch rollers determine direction. Flywheel diameters compensate for inside/outside belt diameter. Only speed adjustment was screw-driver inside the motor housing itself. Harman Kardon HK300 had a single flyheel, spindle impressed alternately on fw or rev through a clutch that was always disintegrating. Same in-the-motor adgustment. RL All those mechanical means of reproducing sound - wax disks, tinfoil, shellac, plastic, wire, tape - were all awful. Chemical photography was a nuisance, too. Ditto typing and carbon paper. -- John Larkin Highland Technology, Inc lunatic fringe electronics |
Why are capstan wheels different size?
On Sat, 12 Mar 2016 12:19:34 -0800, John Larkin
wrote: On Sat, 12 Mar 2016 13:06:27 -0500, legg wrote: On Sat, 12 Mar 2016 17:37:50 +0000, N_Cook wrote: On 11/03/2016 21:22, DaveC wrote: Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Aiwa AD WX888 , 1997,I worked on once, spindle to one capstan 2.49mm diameter and the other 2.69mm Aiwa ADR470, forward flywheel was inside the loop, reverse was outside the loop. Both always driven. choice of pinch rollers determine direction. Flywheel diameters compensate for inside/outside belt diameter. Only speed adjustment was screw-driver inside the motor housing itself. Harman Kardon HK300 had a single flyheel, spindle impressed alternately on fw or rev through a clutch that was always disintegrating. Same in-the-motor adgustment. RL All those mechanical means of reproducing sound - wax disks, tinfoil, shellac, plastic, wire, tape - were all awful. Chemical photography was a nuisance, too. Ditto typing and carbon paper. Yeah but look at the bit-error rate you can tolerate. A CD would be worth less with that many errors. Cheers |
Why are capstan wheels different size?
On 12 Mar 2016, John Larkin wrote:
All those mechanical means of reproducing sound - wax disks, tinfoil, shellac, plastic, wire, tape - were all awful. Chemical photography was a nuisance, too. Ditto typing and carbon paper. Yeah, yeah, yeah. Gotta have a source platform in order to digitize all that media... |
Why are capstan wheels different size?
MJC wrote:
Sure, but my point was that any chatter in the bearings is just as bad as rotational variation and is not damped by the flywheel. So the plain bearings have to be accurate and long-lasting. ** You have completely forgotten the damping effect of side-ways pressure from the pinch roller. I certainly was not taking it into account. Probably because it is movement along the length of the tape and not sideways that gives rise to speed modulation at the pick-up. ** Just to rub it in, the SIDEWAYS pressure from the pinch roller forces the capstan shaft against the bearing and inhibits any "chattering". I really works and I see machines ( ie Roland Space Echos) with noticeable play in the capstan bearing that have low W&F. ..... Phil |
Why are capstan wheels different size?
DaveC wrote:
By my mind that is backward: the pinch roller is passive (not being driven). The capstan shaft (~2mm diam) is driven by capstan flywheel/belt/motor pulley. ** Tape speed is determined by the surface speed of the motor pulley divided by the flywheel to capstan diameter ratio. That ratio might be 20:1 making the pulley surface speed 37.5 inches/S for a standard cassette speed of 1-7/8 inches/S. ..... Phil |
Why are capstan wheels different size?
"The capstan is a passive device. The motor pulley diameter via the *pinch roller* determines the tape speed. The capstan wheel can be any size at all.
Peter Wieck Melrose Park, PA " Absolutely false. the pinch roller can be any damn diameter is want. The tape speed is controlled by the driven element of the system which is that capstan and is exactly its RPM times its diameter and of course Pi. Alot of people misunderstand this, especially in the US. Same thing with the idler wheel on a turntable, it can be bigger or smaller, doesn't mean ****. the ratio that matters there is the motor to the rim, which is the driven element. On tape, the speed is precisely controlled by the capstan and that is based on the capstan diameter. ONLY. The pinch roller can be as big as a truck tire and it still goes the same speed. Y'know, when I was in school they gave me this test. Turns out I was in the 99th percentile in mechanical reasoning. I liked that part of the test, gears n ****. When I started corresponding internationally, I thought that too high. People in some countries are smart as all hell. So in the world maybe I am just a 50. But the thing is, here we got guys who cannot figure out how to change a flat tire. (tyre for you oppressive folks across the pond we had to kick out of our jungle because of your damn taxes) I did not learn any of this **** in schools. The schools here don't teach that useful information, or as far as I could see any useful information. You can plainly see those flywheels move in opposing directions, but there was a disconnect. I can't fault people for that, it is a deficiency in their education. In this country, peoples' Parents worked too ****ing much and thought the schools would teach their kids. Didn't work. I am not trying to put anyone down, I understand how it is, but the bottom line is this question should never have been asked. |
Why are capstan wheels different size?
Wrong !
The linear speed is RPM/60*pi*D (D in meter), eventually *100 if it's given in cm/s ; for a cassette it is 4,75 cm/s. It is determnied by the little axis that tha tape is pinched to. a écrit : "The capstan is a passive device. The motor pulley diameter via the *pinch roller* determines the tape speed. The capstan wheel can be any size at all. Peter Wieck Melrose Park, PA " |
Why are capstan wheels different size?
On Sat, 12 Mar 2016 12:19:34 -0800, John Larkin
wrote: On Sat, 12 Mar 2016 13:06:27 -0500, legg wrote: On Sat, 12 Mar 2016 17:37:50 +0000, N_Cook wrote: On 11/03/2016 21:22, DaveC wrote: Oh, smarter-than-I people, http://imgur.com/WPEoOu1 The 2 belt-drive capstan flywheels in an auto-reverse cassette mechanism are different sizes. (Motor drive pulley will be in the small loop end of the belt in illustration above.) How does that result in the same tape speed in both directions? Confused... Aiwa AD WX888 , 1997,I worked on once, spindle to one capstan 2.49mm diameter and the other 2.69mm Aiwa ADR470, forward flywheel was inside the loop, reverse was outside the loop. Both always driven. choice of pinch rollers determine direction. Flywheel diameters compensate for inside/outside belt diameter. Only speed adjustment was screw-driver inside the motor housing itself. Harman Kardon HK300 had a single flyheel, spindle impressed alternately on fw or rev through a clutch that was always disintegrating. Same in-the-motor adgustment. RL All those mechanical means of reproducing sound - wax disks, tinfoil, shellac, plastic, wire, tape - were all awful. Chemical photography was a nuisance, too. Ditto typing and carbon paper. I can't think of a single method of 'reproducing sound' that doesn't involve mechanical means. Sound is a mechanical phenomenon. Humans use flapping meat. Perhaps you mean recording? No, still mechanical. Storage? Maybe. Of course, there's nothing mechanical in electronics, is there... It's the programme material, the idea and its conception that's important; not the means of conveyance. RL |
Why are capstan wheels different size?
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Why are capstan wheels different size?
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Why are capstan wheels different size?
In article ,
MJC wrote: In article , says... I can't think of a single method of 'reproducing sound' that doesn't involve mechanical means. Sound is a mechanical phenomenon. Humans use flapping meat. I can imagine a method that used heat to move the air, perhaps with a plasma to make it fast. (Like a modulated lightning flash.) But I cannot be bothered to construct a search to find out if it has been done successfully... Mike. I recall a conversation from years ago with a *VERY* old theater projectionist, who spoke of what he called "flame speakers". Don't know if it was an artifact of his (at the time) 80+ year old mind going, or reality, but what he described made sense to me on several levels, though I've never bothered to try chasing it down. Apparently, back in the early days of talkies, one method of sound production involved a gas nozzle (unsure if he meant gasoline, or something like propane/LP gas) "tuned" to produce a blue flame (he was very clear on that point - lots of the conversation came back to how he had to tinker with the flame at each showing, otherwise the sound wasn't good) several feet tall in a combustion chamber, into which was shoved a set of tungsten electrodes. The 'trodes were driven at high voltages by any of several amplification methods (frequently varying by theater, if the old guy's tale was to be believed) to charge the plasma of the flame, which apparently caused it to "dance", driving a diaphragm like that of a speaker. Supposedly, amazingly high volumes with very good fidelity could be achieved. Like I say, I've never actually gone to the effort of tracking it down, and I have no idea if it was a failing mind's invention, or reality, but... shrug Seems to me like it COULD work. -- Security provided by Mssrs Smith and/or Wesson. Brought to you by the letter Q |
Why are capstan wheels different size?
"I can imagine a method that used heat to move the air, perhaps with a
plasma to make it fast. " The singing arc. However it depends on how you want to be about this. If someone want no moving parts that is fine and the singing arc works for that. But your eardrum still moves as well as the linage from it to the cochlea. Plus the fact that the air itself moves. |
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