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Interest In Making New PT Motor Controllers?

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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 12 Feb 2017 02:02

Partlist:

Part Value Description Mouser PART#
C1 470uf CAPACITOR POLARIZED 647-UKL1H471KHD
C2 10uf CAPACITOR POLARIZED 667-EEU-EB1H100SB
C3 10uf CAPACITOR POLARIZED 667-EEU-EB1H100SB
C4 2.2uf CAPACITOR TANTALUM 581-TAP225K020SCS
C5 0.1uf CAPACITOR FILM 594-2222-368-45104
C6 1uf CAPACITOR FILM 505-MKS41/100/5
C7 0.1uf CAPACITOR FILM 594-2222-368-45104
C8 0.01uf CAPACITOR CERAMIC 80-C322C103J5R
C9 0.01uf CAPACITOR CERAMIC 80-C322C103J5R
D1 TZX4V7D Z DIODE 78-TZX4V7D
IC1 LM317 VOLTAGE REGULATOR 926-LM317AT/NOPB
IC2 CA3240AEZ DIL8-DUAL-OPAMP 968-CA3240AEZ
IC3 LM7809 VOLTAGE REGULATOR 512-LM7809CT
Q1 BD136-16 NPN TRANSISTOR 512-BD13616S
Q2 BD135-16 PNP TRANSISTOR 512-BD13516S
Q3 BC558B PNP Transistror 512-BC558BTA
R1 10r RESISTOR 603-MFR50SFTE52-10R
R2 56r RESISTOR 603-MFR50SFTE52-56R
R3 220r RESISTOR 603-MFR50SFTE52-220R
R4 1k5 RESISTOR 603-MFR50SFTE52-1K5
R5 1k8 RESISTOR 603-MFR50SFTE52-1K8
R6 2k7 RESISTOR 603-MFR50SFTE52-2K7
R7 4k7 RESISTOR 603-MFR50SFTE52-4K7
R8 7k5 RESISTOR 603-MFR50SFTE52-7K5
R9 8k2 RESISTOR 603-MFR50SFTE52-8K2
R10 33k RESISTOR 603-MFR50SFTE52-33K
R11 39k RESISTOR 603-MFR50SFTE52-39K
R12 150k RESISTOR 603-MFR50SFTE52-150K
S1 CK1062 ROTARY SWITCH 10SM162
T1 1k Trimm resistor 652-3386P-1-102TLF
T2 1k Trimm resistor 652-3386P-1-102TLF
T3 20k Trimm resistor 652-3299W-1-203LF

DC-IN CONNECTOR-2 Pin 2.54MM PITCH SCREWDOWN Ebay search for '2.54MM PITCH SCREWDOWN'
MOTOR CONNECTOR-2 Pin 2.54MM PITCH SCREWDOWN Ebay search for '2.54MM PITCH SCREWDOWN'
TACHO CONNECTOR-2 Pin 2.54MM PITCH SCREWDOWN Ebay search for '2.54MM PITCH SCREWDOWN'
J1 JUMPER-7MM WIRE From a Resistor/Capacitor Leg

EXTRAS:
TRANSFORMER 30va x Your country's mains volatgs x single 12vac
Bridge Rectifier 50v 3A 844-KBPC1005

Notes:
the above is to use a 9v motor.
Change out the LM7809 for the voltage of your motor e.g. if you have a 12vdc motor then use LM7812.
if you change the LM78xx then you must also change the transformer and go 3vac up e.g. for 12v use a 15vac transformer.
i would not go any higher than a 12v motor
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Re: Interest In Making New PT Motor Controllers?

Postby Capt Zach » 13 Feb 2017 16:24

Very nice job! I like your improvements to the circuit. Once I've finished the clone of the original, I will try adapting the circuit to the Funk Firm style case, with integrated front switch, dual single LED, pcb transformer, holes for front speed adjustment, etc.

Motors very close to the original PT can be found in turntables from the era. B&O used them in some Beograms, and I believe Garrard also used them in some of their GT line.
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 19 Feb 2017 16:02

it has just occurred to me that we could put the tacho on the platter rather than the motor. all the tacho is doing is counting pulses and relaying these to the circuit to keep the speed constant on the motor.

now the fun part, as far as i know the only thing constant on PT's is the platter spindle boss size. if we use an optical encoder then we could get stickers made up with the correct markings to fit the inside hub (where the belt goes round) and use that as the 'counter' for the optical encoder :-)
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 28 Feb 2017 01:18

here is the latest.

Board.jpg


board measures 8cm x 10cm. its designed it to fit in a case with a vertical 3pole 3way rotary switch. there is an added a facility for two LED's which switch between 33/45. case will also house the transformer and should be 10cmW 5cmH x 20cmL. so pretty dinky :-)

there is a full rectified dual linear power supply with a ground plane which helps with unwanted noise entering the system. i have also added two small caps on the opamp to keep it from oscillating if needed which i doubt but they are there anyway.

all traces are a direct replacement of the originals as we know the boards work.

i have tracked down some tacho motors that are used in tape decks so should be of decent quality. these have 4 wires just like the original motors. they are bigger but fairly short 37mm wide x 50mm tall. dont know the speed till they get here then i can get pullys made for them.

i'm going to send off and get a small batch of boards made up and build one for testing with the motors.

if it works which i see no reason for it not too i think this would make a superb replacement for LPT and PTTOO tables which by chance i just happen to have :-)

now if someone had an anniversary board knocking about that i could take a look at i could update these to anni spec :wink: :wink:

one more thing. i have been looking into using a optical sensor for the tacho and so far it looks doable. i have also sussed out how to get the markings on the platter, use heat transfer paper and iron them on like making pcb's. if not then its 0.25mm brass acid etched out.

back emf is going to take a while and i might not even bother depending on how well this works.
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Re: Interest In Making New PT Motor Controllers?

Postby Cloudbase » 28 Feb 2017 12:40

now if someone had an anniversary board knocking about that i could take a look at i could update these to anni spec :wink: :wink:


I think i took some pics of the top (component side) of my Anni when i delved inside on buying it when i tweaked the internal trim pots using a rough n ready printed paper strobe.
Im at work but if thats any use i can have a look when i get home?

By the way, awesome thread by everyone involved.
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 28 Feb 2017 14:45

Cloudbase wrote:
now if someone had an anniversary board knocking about that i could take a look at i could update these to anni spec :wink: :wink:


I think i took some pics of the top (component side) of my Anni when i delved inside on buying it when i tweaked the internal trim pots using a rough n ready printed paper strobe.
Im at work but if thats any use i can have a look when i get home?

By the way, awesome thread by everyone involved.


i would need to see the bottom traces of the PCB, component values and positions. i have a feeling that its not that much different from the PT1 board though.

what i would really like is the same but one of the newer back emf boards like the k-drive or vx just to see whats going on.

placing the tacho on the platter means that we can use any motor we like :wink: using magnets would be the easiest solution but i dont want to do that.
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 01 Mar 2017 19:49

no rest for the wicked :lol:

EMF.jpg


i found a back emf circuit over on pinkfish that has mixed reviews, i personally think that some people never really understood what was needed to get the circuit stable as a few people managed it and some never. i think the secret with that circuit is to stick to one motor and design the component values around that. i would personally prefer to get a motor that is easily obtainable like one of the lesser priced maxton motors and use that for the final design values. that way people know the exact motor to use instead of messing around with component values.

what i have done is hack the pinkfish back emf portion of the circuit into the speed change circuit of the pt1, basically inserting the back emf where the tacho part was.

again the design has full dual linear power supply onboard.
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Re: Interest In Making New PT Motor Controllers?

Postby tim_bissell » 05 Mar 2017 16:11

That looks great; I wish I had the time and inclination to learn the electronics necessary; maybe when I retire! I think it is a good idea going with the Maxton motors. I think any system based on feedback is more complicated than people think, and tuning the circuit with the selected motor to avoid 'hunting' and abrupt adjustments in speed and audible effects is very important.

Have you any plans for sourcing well-machined pulleys? Would you be planning on using flat belts, or moving to rega-style round ones (personally I would go for the former)

I have parts for a PT without a working motor (but with a spare PT1 pulley), so I am happy to provide a testing facility, and pay for PCBs etc.

-- Tim
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 06 Mar 2017 02:35

thanks for the offer Tim. pulleys are cheap enough to get made up.

i prefer flat belts as round has to be round or they walk up and down the sub platter.

now what i have learned about the PT1 circuit is that the lm317 is there to set the 33/45 voltage with the two speed pots. the single pot is there to adjust drift/hunting. the only problem with the PT1 circuit is that there is no input regulation from the mains which would cause fluctuation as the mains voltage rises/falls.

i have found a few TI datasheets for back emf design and its pretty much exactly the same as the pinkfish but uses a single opamp which are expensive (£10 a pop).

i'm finalising both designs then i'll send off for some boards and test.

TBH i have a few ideas i would like to implement like split platter/sub platter and a bearing idea. one step at a time though.

on a side note.. both my platters have a sub platter diameter of 133.??mm any chance of measuring the ones you have.

you will be my first port of call for testing Tim :-)
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Re: Interest In Making New PT Motor Controllers?

Postby basket weaver » 07 Mar 2017 21:54

Hi
I had a problem with my PT1 motor and have replaced it with an escape motor with tacho, all but with a 2mm output shaft. should have a 3mm shaft.
Anyway. If you're on the hunt for motors. I've now found these at 80 euros
http://www.toolex.com/index.php?route=p ... ct_id=2268
I've contacted the trader and they have 3mm shafts. the ref number suggest they have roller ball bearings rather than just a brass/bronze bush top and bottom.

--phil
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 08 Mar 2017 04:41

thanks for the info. interesting that you confirm my theory about the 'servo' being a tacho.

i think i'm going to concentrate on EMF rather than tacho.

i'll get both boards made up and try them.
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Re: Interest In Making New PT Motor Controllers?

Postby backtotheblack » 16 Mar 2017 23:42

i'm starting to go off the idea of Maxon motors. i think they make up numbers as they please for customers and when you try and find a reference to them they don't exist, add to that the website is a complete nightmare to navigate. i'm thinking they only want to sell new motors in high volume to companies and 'stuff you' if you have an older one and want information.

yes i understand that they have millions of motors/parts but how hard is it to get your model numbering sorted.. not very, and i thought the swiss were organised people.. lol

rant over :-)
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Re: Interest In Making New PT Motor Controllers?

Postby limono » 06 May 2017 16:12

On one of my PT-1 decks with 44XX numbers which I have for sale I noticed that there is a red LED installed lurking through the speed adjusting holes on the controller board (which other decks from the same year of production lack) I did not pulled the top plate to check it out but I may. Different version of that controller ??
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Re: Interest In Making New PT Motor Controllers?

Postby Capt Zach » 18 May 2017 14:59

Yes, I've seen at least one other version of this controller like you describe, there are a few pictures of it in the gallery.
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Re: Interest In Making New PT Motor Controllers?

Postby tim_bissell » 20 May 2017 11:04

backtotheblack wrote:it has just occurred to me that we could put the tacho on the platter rather than the motor. all the tacho is doing is counting pulses and relaying these to the circuit to keep the speed constant on the motor.

now the fun part, as far as i know the only thing constant on PT's is the platter spindle boss size. if we use an optical encoder then we could get stickers made up with the correct markings to fit the inside hub (where the belt goes round) and use that as the 'counter' for the optical encoder :-)


The Helius Designs Alexia turntable has a disc like this ; it would be interesting to see how to combine digital with analogue, I guess a lot would depend on the quality (accuracy, stability, resolution) of the D-A converter

-- Tim
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