my diy project

[moimeme_81]

JosM it's beautiful but I don't like the style of it, the principle of the tonearm I'll build is the same so unipivot but I want it to be almost only wood the rest will be brass if I need to add any metal parts. but what kind of motor did you used, what's the length of the tonearm, is that a pro-ject speed controler on top left corner?

thanks
chris

[JosM]

Hi Chris,

On the left side you see a homemade powersupply 12 Volt DC stabilized for the motor. The length of the arm is 10 inches. I use a FG (Frequentie Generated) DC servomotor from an old japanese turntable. Adding a 12 volt DC powersupply, two resistors( 45 and 33 speed), a switch and a potmeter and you are ready to operate. You find these motors in old Technics and Pioneer turntables etc.

[moimeme_81]

hi,

you got the schematics of that power supply so I can compare with my idea of using an ac synchronous motor at 60hz coming from a ac-dc-ac power supply (12vac to 24vdc stabilized to 16vac phase stabilized so I get the exact speed I need give only one speed though)

thanks
chris

[JosM]

Hi Chris,

The 12 Volt DC power supply is a "standard" DC supply with a common IC 7812.

[moimeme_81]

hi,

then there's something I don't get in your set up. because the motor require a pulse to control it's speed, but maybe I'm missing something too.

[JosM]

Hi Chris,

All the electronic control is in the housing of the motor. You just need a 12 Volt DC power supply and a potmeter in serie with a rsistor to control the speed.

Jos

[moimeme_81]

hi,

OH!!!! ok I definitely missed something... I'll look for that instead of my over-complicated system thanks for sharing

chris

[moimeme_81]

here's a link to the circuit design I made, considering the motor I'll use... (from a yamaha p-350)
https://www.circuitlab.com/circuit/qw54 ... ply-5-15v/

it seems a little complicated but there's 2 power-supply (33/45) and a ripple reducer so it's even more accurate.

chris

[moimeme_81]

hi,

last night, I just couldn't sleep so I decided to get my hands dirty and look at the sony ps-t1 I was planing to salvage for my current project and I understood/learned a lot of things, fisrt the motor isn't an ordinary dc servo but a hall effect dc servo, a motor that should be almost as precise a quartz controlled system but the electronic isn't stable enough because of the voltage regulator and the magnetic interference of the motor to the magnetic coated platter. but still the control unit is similar to a fg dc servo so I've been able to run some test to prove right or wrong what I thought. first I learned that I can trash one half of the circuit I had designed because of a mistake of interpretation in the design of the motor. second it confirmed what I thought about the bearing, it's a piece of s**t, you can't really lube it and the magnet is pushing on it. third, the only pieces that can be kept from the TT are screws, some pots, a switch and a point bearing. fourth, the pitch control is really bad, the strobe is controlled by the phase directly from the wall which is variable...

doesn't seem like the most interesting night but it was cool

Chris

[JosM]

Hi Chris,

Try to purchase a Lenco L75 turntable. You can use the bearing and the platter of it. Or buy only the platter and the bearing on E-bay. Not expensive 50 Euro or so.
See my pictures. Jos

[moimeme_81]

hi,

that would be a good idea but I like the idea of the harley davidson intake valve as a bearing (altmann TT) which I can find for much cheaper than 50€ plus I have a point bearing that fits the the bearing ball that the bottom needs salvaged from a laser cnc so I'll look at that first then consider buying a lenco.

thanks for the advice though
Chris

[magnaflux]

At this moment I have finished the turntable including the tonearm. It performs great! The tonearm is made of a tube. I use litze wire from an old coil of a medium wave radio. I use also aluminium folie in the tube as a earthscreen.

Sweet!

[JosM]

thanks!

[oatstao]

At this moment I have finished the turntable including the tonearm. It performs great! The tonearm is made of a tube. I use litze wire from an old coil of a medium wave radio. I use also aluminium folie in the tube as a earthscreen.

Fun project. Thanks for sharing the pics and ideas.