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Turntable Tachometer and motor speed controller

This is a group buy for the combined turntable tachometer with motor speed controller that uses the feedback from the optical sensor to keep the speed locked at 33.33 or 45 rpm. The control loop uses PID control. You can just use the board as a drop in-replacement for the Linn Valhalla board without the sensor and OLED display if you wish to solve the heat and unreliability problems of the Valhalla and just get electronic speed switching. Works fine with other turntables that use compatible synchronous motors.

The full thread discussing the development is here:
Digital Tachometer for record player (LCD display)
Features:

• Electronic switching between 33.33 rpm and 45 rpm (no more pulleys)
• Highly accurate sine wave frequency synthesis generated for 50Hz or 67.5Hz controlled to 0.001 Hz
• Class A motor drive circuitry.
• Optional optical platter feedback sensor to lock platter rotation at exactly the right speed. This runs a PID controller loop reach maximum speed quickly then keeps rotation speed locked rock solid.
• Control over motor parameters such as frequencies, phase angle, voltage amplitude via a USB serial interface. Adjusting these values enables smoothest motor operation with minimum motor noise and vibration. Values may be written to EEPROM once optimum setup achieved.
• OLED display to indicate exact platter rotation speed and WOW
• Fits on original Linn Valhalla mounting
• Can connect to original Linn power switches.
• Speed change controlled by holding power switch for three seconds
• Less heat generated than original Valhalla due to redesigned PSU section (no more burned out resistors).
• May be used for other turntables that use a two phase synchronous motor such as Airpax, Premotec, Philips e.g. Rega, Linn, Manticore, Pro-Ject etc.
• Can be housed in a separate box.
• Uses standard commonly available low cost parts such as Arduino, AD1933 DDS generators, common transistors.

There are three options:

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts as per attached BOM in above thread 58.00 GBP
3) Fully assembled and tested board 98.00 GBP

a) If you want the optional FFC / FPC RA header so you can use a Linn flexible circuit switch (e.g. if fitting inside a Linn LP12 replacing a Valhalla) then that's 1.00 GBP extra.
b) Recommended round momentary push switch/LED to fit OLED enclosure (see below). £4.50

Options 2 & 3 are complete with all parts (I2C 128x32 OLED display, DDS generator PCB's, Arduino, IR detector, passives, semiconductors, heatsinks. terminal blocks etc.). All you need to add is a power switch (momentary action), indication LED and external enclosure for board (if not fitting inside TT). You will get a 3D printed box for OLED & Speed sensor. You can also use this box to mount a stop/start/speed change switch.

If you want shipping outside of UK please contact me with your address and I will work out how much extra it will be. Some examples of tracked pricing are Europe £9.35 USA £10.55 GBP

This kit contains a SMPS that is not isolated from the mains supply (similar to Linn Valhalla board). I recommend you build and test with an isolation transformer/step down transformer (100 - 240v @ 120mA) for safety of you and your test equipment. You must be confident and competent working with voltages 90V - 320V.

The above being said, the kit is straightforward to build and I will provide full comprehensive instructions on safety procedures, modular build and testing plus actual setup with your turntable. There are some SMD resistors to solder on the underside of the board. The most difficult part is tuning the PID parameters via serial interface/tuning application but some examples are supplied.

As a reminder these boards are designed to work with 2 phase synchronous motors 50Hz/60Hz that work off 6V - 110V RMS (160v p2p) that have a current consumption of approximately 10mA per phase. AKA Premotec, Airpax, Philips motors as used in Linn, Rega, Manticore, Pro-Ject and other compatible turntables Two boards can be stacked to drive 3 or 4 phase motors. You may be able to use them on shaded pole motors by using a single phase as long as the voltage and current requirements match the board specifications above. I have not tested on anything other than synchronous motors. If your motor draws more current/voltage then you will need to use an off board supplementary amplifier as per Pyramid's SG4. This motor controller can be used as a source for the sine waves and to handle the tacho & feedback/control functions.

To proceed with the group buy please add your name to each of the categories below. Please copy and paste the whole list each time you post so the list contains running additions and I don’t have to go hunting through each thread.

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
a) Linn Valhalla switch connector option 1.00 GBP
b) Momentary action switch/LED to fit OLED enclosure 4.50GBP
 

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Last edited:
Hi yes almost all Rega motors are synchronous motors. However, a note to everyone who is interested you must check your own motors as I don't know what's in every turntable. I have attached a picture of a synchronous motor - almost all look like this. The voltage or frequency does not matter as those can be set on the controller board. They all have 4 wires which are usually two grey one red and one blue. I have attached a schematic of how the board is wired up.

Even turntables that run off 220v have 110v motors with a resistor/capacitor network. The resistor/capacitor network is removed and the motor is wired directly to the board. This gives the quietest and best motor drive conditions. You may need to mount the controller in an external box if your turntable has a thin platter like a Rega.

Correct
 

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ZUM911

Member
Paid Member
2006-01-31 6:22 am
Sydney
not sure Dieter was after but I'll add to the list mine.

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
a) Linn Valhalla witch connector option 1.00 GBP
b) Momentary action switch/LED to fit OLEE enclosure 4.50GBP
1 for DieterK


ZUM911 1 x 2,a,b
 
Hi,

In the fully assembled kit you get the controller, platter sensor, OLED display, the small enclosure box for sensor & display. If you want to mount the controller in an external case (If your turntable plinth is solid or not big enough) you will need to provide that yourself as it will be a matter of taste. I have used a Hammond 1455 extruded aluminium enclosure for my system. The PCB is 100x160mm and you need at least 25mm height.


Thanks for the infos


Is the box included in Fully assembled and tested board 98.00 GBP

What about the plater senser ?

Serge
 
Last edited:
Zum911 thanks. Need to keep the formatting as below. Please check it's correct:

QUOTE=ZUM911;6087656]not sure Dieter was after but I'll add to the list mine.

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for ZUM911
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
b) Momentary action switch/LED to fit OLEE enclosure 4.50GBP
1 for DieterK
1 for ZUM911


ZUM911 1 x 2,a,b[/QUOTE]
 
1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for ZUM911
1 for koldby
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
b) Momentary action switch/LED to fit OLEE enclosure 4.50GBP
1 for DieterK
1 for ZUM911
 

al2002

Member
2003-12-15 6:41 am
USA
1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for ZUM911
1 for koldby
3 for al2002
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
3 for al2002
b) Momentary action switch/LED to fit OLEE enclosure 4.50GBP
1 for DieterK
1 for ZUM911
_____________
 
ZUM911 I have amended the list for you:

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GB
1 for ZUM911
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for koldby
3 for al2002
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
3 for al2002
b) Momentary action switch/LED to fit OLED enclosure 4.50GBP
1 for DieterK
1 for ZUM911
 
Hi Godataloss, unfortunately I have no idea what kind of motor is in that turntable. You will need to do your own research. If you look at the two posts on page 1 I have provided information on how to identify if your TT uses a synchronous motor or alternatives. Shaded pole motors e.g. Lenco's require additional step up amplifiers. Good luck.

Will this work with VPI HW 19 motors?
 
1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GB
1 for ZUM911
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for koldby
3 for al2002
1 for Sergelisses
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
3 for al2002
1 for Sergelisses
b) Momentary action switch/LED to fit OLED enclosure 4.50GBP
1 for DieterK
1 for ZUM911
1 for Sergelisses
 
1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GB
1 for ZUM911
3) Fully assembled and tested board 98.00 GBP
1 for DieterK
1 for koldby
3 for al2002
1 for Sergelisses
1 for JensenHealey
a) Linn Valhalla witch connector option 1.00 GBP
1 for ZUM911
3 for al2002
1 for Sergelisses
b) Momentary action switch/LED to fit OLED enclosure 4.50GBP
1 for DieterK
1 for ZUM911
1 for Sergelisses
1 for JensenHealey
 

chromenuts

Member
Paid Member
2008-12-27 7:27 am
Connecticut, USA
Here’s two examples of motors pulled from VPI turntables. They are both synchronous and can be run 2 phase or single phase with a cap.

The one that is simply engraved with the specifications is the original motor out of my early HW19.

The labeled motor is a backup pulled from another VPI turntable with essentially the same specs, albeit a different part number most likely due to the fact that it was produced much later.

VPI pretty much used the same motor for all its turntables for years. They eventually switched to a 300 RPM version that was rated at 7.5W which you can find in the drive units for tables like the TNT etc.


Here is a link to Hurst’s current line of PA and PB motors.

PA, PB Direct Drive Permanent Magnet AC Synchronous Motors

No data is given as to how much current is consumed by these motors per phase as far as I can see. Maybe it can be figured out from the data provided.


I personally have completely done away with these motors and modified my HW19 to utilize the DIY SG4 4 Phase Sinewave generator and 3 channel class D amp that DIY member Pyramid designed to use with an Anaheim Automation 3 phase motor. He also is responsible for the Pheonix engineering Falcon controller and Roadrunner tach which I still own. The Falcon was limited to use with lower (i.e.5.5 watt) motors.


Link to my HW19 rebuild.

VPI resto-mod...a tale of bastardizing my HW19


Although I did integrate my Roadrunner tach into my control system to monitor speed, it is unfortunate that the SG4 is not capable of a feedback loop that allows speed regulation as the Falcon controller could with the lower watt motors.

I would be interested in this group buy if there was a way to integrate the tach feedback feature to regulate speed and still utilize my SG4/Amp/Motor combination.



Hi Godataloss, unfortunately I have no idea what kind of motor is in that turntable. You will need to do your own research. If you look at the two posts on page 1 I have provided information on how to identify if your TT uses a synchronous motor or alternatives. Shaded pole motors e.g. Lenco's require additional step up amplifiers. Good luck.
 

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