4 euros for the motor...
Am I looking for a sinewave generator kit with variable frquency AND voltage? I think that's what I need isnt it?
oh no, it also needs the 90 degree channel. that makes it harder.
Wow I just found sinewave generator kits for $14.99AU with adjustable freq. and amplitude.
What's amplitude?
(shrugs)
Am I looking for a sinewave generator kit with variable frquency AND voltage? I think that's what I need isnt it?
oh no, it also needs the 90 degree channel. that makes it harder.
Wow I just found sinewave generator kits for $14.99AU with adjustable freq. and amplitude.
What's amplitude?
(shrugs)
# Both the amplitude and frequency are voltage controlled.
# Circuit includes a voltage regulator for good stability. Can be powered from a 1x9V battery or DC supply between 8.5V and 15V.
# Output frequency range: 10Hz-100kHz in 4 bands.
# Output level (0-5V p-p load 250W)
Would two SWG's specced as above suit my needs?
# Circuit includes a voltage regulator for good stability. Can be powered from a 1x9V battery or DC supply between 8.5V and 15V.
# Output frequency range: 10Hz-100kHz in 4 bands.
# Output level (0-5V p-p load 250W)
Would two SWG's specced as above suit my needs?
planarboy, seems like you've found a solution...
But how do time the two amps so that they are 90 degrees out of phase? Do you create a circuit with a J-K flip flop or digital logic? And then you really need DC to do that.
I think the benefit with an MP3 player is that you create tracks that are 60 minutes long, and that it is very easy to re-record a different frequency to adjust for different diameters of pulleys and platter drive pulley or inner platter. I think this is where the true "beauty" lies in this system. And also that there is "DC drift" when using DC motors. This system negates the effects completely.
convenience: When you are done listening to a side press "Stop". When ready to start, press "Play". Sounds like most everybody who switched to "Perfect Sound Forever" had the same issue. Get up, stop turntable. Switch record. Press "Start" or "Play". Cue arm. Sit down and listen to 25 minutes of music at a time.
Not trying to be a jerk here, BUT....
seems like all who listen to analog expect this sort of thing when listening...
as far as the requirements, not sure how much current is required for your chosen motor. But 5-7 watts typically do it for small DC motors.
But how do time the two amps so that they are 90 degrees out of phase? Do you create a circuit with a J-K flip flop or digital logic? And then you really need DC to do that.
I think the benefit with an MP3 player is that you create tracks that are 60 minutes long, and that it is very easy to re-record a different frequency to adjust for different diameters of pulleys and platter drive pulley or inner platter. I think this is where the true "beauty" lies in this system. And also that there is "DC drift" when using DC motors. This system negates the effects completely.
convenience: When you are done listening to a side press "Stop". When ready to start, press "Play". Sounds like most everybody who switched to "Perfect Sound Forever" had the same issue. Get up, stop turntable. Switch record. Press "Start" or "Play". Cue arm. Sit down and listen to 25 minutes of music at a time.
Not trying to be a jerk here, BUT....
seems like all who listen to analog expect this sort of thing when listening...
as far as the requirements, not sure how much current is required for your chosen motor. But 5-7 watts typically do it for small DC motors.
planarboy said:
In order: No it can't. Have you ever measured the cogging from a stepper motor? In my opinion they are totally unsuitable for turntable use.
Amplitude is the "size" of the wave. If the amplitude and the frequency are voltage controlled (EG it's a VCO) then both the amplitude and the frequency will shift when the control voltage drifts.
You can't use two independent oscillators to establish quadrature, especially not ordinary VCOs. The phase difference is uncontrolled and it will wander all over the place; the motor will then change direction. Think about it : if the two generators differ by only 100 parts per million then a 90 degree phase error will accumulate in 2,500 cycles which is under a minute at 50Hz.
Designing a stable two channel oscillator with fine scale control of frequency, amplitude, quadrature angle and distortion is not a trivial exercise. As far as I know my kit is the only such device available.
Mark Kelly...
I have one of the Maxon GB boards(and motors pulleys and POD), and I will be using that personally. I am also going to use the system that is used here:=http://www.altmann.haan.de/turntable/ has on his site using stepper motors. It is very easy to use and very east to implement. I have no reason to believe Mr. Altmann's system will work (nor do I have any reason to believe your system won't
).
I've personally not tried to build a speed controller, but there must be a crystal oscillator, perhaps a PPL, , a voltage regulator, and a few divide by 2 implementations in it (I also haven't read the instrux yet either though), then a variable voltage source, and circuitry to help with DC drift (which I'm assuming is due to the thermal and therefore the resistive characteristics of the windings in the motors themselves).
quite similarly a cd or MP3 file at 50 or 60 Hz (or a fine tune to adjust stable speed) can be used with a large power amp to create a stable frequency source (with enough voltage) to run an Ac Synchronous type motor. Or provide a clean AC signal.
Again, I know I have been criticized for suggesting simple implementations, but if the desired end results inexpensively for many then why not?
Please PM me if you would like to expand this into a personal discussion and not intrude further into the thread (only as a courtesy to others in this thread, and in no way am I suggesting you are intruding--call it a suggestion to help keep the thread "on track")
stew
I have one of the Maxon GB boards(and motors pulleys and POD), and I will be using that personally. I am also going to use the system that is used here:=http://www.altmann.haan.de/turntable/ has on his site using stepper motors. It is very easy to use and very east to implement. I have no reason to believe Mr. Altmann's system will work (nor do I have any reason to believe your system won't
). I've personally not tried to build a speed controller, but there must be a crystal oscillator, perhaps a PPL, , a voltage regulator, and a few divide by 2 implementations in it (I also haven't read the instrux yet either though), then a variable voltage source, and circuitry to help with DC drift (which I'm assuming is due to the thermal and therefore the resistive characteristics of the windings in the motors themselves).
quite similarly a cd or MP3 file at 50 or 60 Hz (or a fine tune to adjust stable speed) can be used with a large power amp to create a stable frequency source (with enough voltage) to run an Ac Synchronous type motor. Or provide a clean AC signal.
Again, I know I have been criticized for suggesting simple implementations, but if the desired end results inexpensively for many then why not?
Please PM me if you would like to expand this into a personal discussion and not intrude further into the thread (only as a courtesy to others in this thread, and in no way am I suggesting you are intruding--call it a suggestion to help keep the thread "on track")
stew
The GB design is an old one which I no longer use. It works as well as any other DC controller available but I've moved on.
The kit to which I referred above is an AC controller.
I came up with the same idea as you a few years ago, here's a phot of an ipod running the motor out of my Garrard 301:
As you can see the amp is a small class D amp wich works very well in this app. I'm playing with a multichannel amp from 41Hz.com, these are very good and very cheap.
The kit to which I referred above is an AC controller.
I came up with the same idea as you a few years ago, here's a phot of an ipod running the motor out of my Garrard 301:
An externally hosted image should be here but it was not working when we last tested it.
As you can see the amp is a small class D amp wich works very well in this app. I'm playing with a multichannel amp from 41Hz.com, these are very good and very cheap.
planarboy se al: morphing a thread and designing a turntable...
As I am not the starter of this thread, I can't say anything but the same.
There are many difficulties in designing a turntable. I've been working on a commercial design and a DIY "kit" for some time. None of it is "trivial" and all the details need to be addressed. To me it seems that the the "devil's in the details" and what better place to work through details than in the planning stage?
So as I see it, here's THE LIST:
of course resonance control considerations need to be addressed along the way.
Sorry if I seemed to pull the thread off course as well.
mark kelly: hmmm, I have an old Lab80 motor kicking around here too. How successful was the iPod/Garrard motor experiment?
stew
As I am not the starter of this thread, I can't say anything but the same.
There are many difficulties in designing a turntable. I've been working on a commercial design and a DIY "kit" for some time. None of it is "trivial" and all the details need to be addressed. To me it seems that the the "devil's in the details" and what better place to work through details than in the planning stage?
So as I see it, here's THE LIST:
- platter and bearing material, type, design, and source
- plinth and possible suspension design including tonearm mount
- motor drive system and all controls required
- aesthetics
of course resonance control considerations need to be addressed along the way.
Sorry if I seemed to pull the thread off course as well.
mark kelly: hmmm, I have an old Lab80 motor kicking around here too. How successful was the iPod/Garrard motor experiment?
stew
Re: planarboy se al: morphing a thread and designing a turntable...
It worked.
Of all the methods I've used to drive the Garrard it was about mid-range, so it was far better than mains power which is at the bottom of the range. This is not the place to discuss the top end of the range.
Nanook said:
It worked.
Of all the methods I've used to drive the Garrard it was about mid-range, so it was far better than mains power which is at the bottom of the range. This is not the place to discuss the top end of the range.
Re: Re: planarboy se al: morphing a thread and designing a turntable...
Mark:
I am considering your AC controller and was wondering what your favorite (I hate to use the word "best") vintage table would be to use with this project and which motor you prefer (and "why", for extra points)
Mark Kelly said:
Mark:
I am considering your AC controller and was wondering what your favorite (I hate to use the word "best") vintage table would be to use with this project and which motor you prefer (and "why", for extra points)
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