Finding a 12V DC motor controller

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audiofilo123

Member
Joined 2005
I'm building up a DIY TT and I pretend to use a 12V DC motor but I'll need a proper controller to set the exact speed (only for 33 RPM set with the help of a strobe disc/light).

I've got a couple of 12V MAXON and one PREMOTEC motor (taken from a REGA P3) and I just need that controller to put things moving :)

I've got a 220/50HZ voltage adjustable power supply model ZETAGI HP156S (Stabilized 4÷16 V 7 A with 2 Instrum).

CAN ANYBODY HELPME TO FIND THE PROPER CONTROLLER? It can be assembled or in kit form.

Thanks :)
 
S

sreten

R.I.P.
Joined 2003
Hi,

The speed of a DC motor is related to the voltage across it.

That is the motor speeds up until the back emf = applied voltage.

So all you need is a precision adjustable voltage supply,
that current limits - this will set your starting torque.

Something like an LM317 with a bandgap voltage reference.

:)/sreten.
 
S

sreten

R.I.P.
Joined 2003
paulb said:
Some form of feedback will be needed to keep the speed constant,
a regulated voltage source will not be enough.
Click to expand...

Hi,

If the DC motor is not designed to be servo'd there is not much you can do.

A DC motor will run near constant speed, drawing more current if required.

The Origin Live dc motor kit is simply voltage driven, no-ones complained
about speed drift is any of the reviews of fitting the OL motor.

:)/sreten.
 
A

Aleksunder

Member
Joined 2006
The the Rega P3 uses an AC motor.

If you got a Premotec DC one from a Rega, it's quite possibly an Origin Live retrofit (the OL kit I bought 4 years ago uses a Premotec), in which case if you still have the Rega, it might have the OL board in it.

If so. and it's still working, all you need is a decent transformer with selectable V out.

A
 
Q

qwertyadam

Member
Joined 2007
if you want to design a motor control unit with a high sensitivity, you can use DPLL.
I have seen something similar before in another forum;
..To generate a true sine wave for your motor and handle the division simultaneously, how about a DDS chip? eg:
http://www.analog.com/en/rfif-components/direct-digital-synthesis-dds/ad9835/products/product.html

With this chip clocked at 5MHz, internal PLL disabled and a 32 bit frequency tuning word, 60*2^32/5e6 = 51539.607552... set that to 51540 for 60hz and your error is -7.61ppm. If having a +3.3V supply on your board is acceptable, the AD9852 chip from the same company provides a 48 bit tuning word - you can get an error of -139 parts per trillion. The latter chip could replace your analog adjustment completely.

These are extremely low jitter - we use them for generating clocks for radio broadcast. You think you audio guys have it hard, try building a FM transmitter - jitter/phase noise is directly demodulated by the receiver!

The only complications are, these chips are fine pitch surface mount so you'll definitely need to make your own PCB to mount them. They have a serial interface (SPI) which you'll definitely need a microcontroller to configure, and you'll need a low pass filter following the chip to eliminate higher frequency tones at 5MHz+-60Hz, 10MHz+-60Hz, etc.
Click to expand...

I could not get this thing running, maybe we could, with the help of knowledgable folks in the forum
 
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