Automatic groove speed controller for VR

[David34]

Hey trolls has anyone played around or made one up?

I know Souri was selling one, but I think he stopped production?

Anyone have any diagrams or know where to locate one?

[MEGAMIKE]

Yes..on the back of the unit that has the groove distant knob there is an rca female and a rca male plug mono.when u take this out it goes at top speed when u put it back in it turns slow again and in time with the groove knob...so u need to midi /cv with software to trigger that rca plug so it makes the gaps automatically in between your trax...on your daw u will need to put the triggers down...
You can also make an external one by using a motor and rubber pully ...ive never tried any of the above but ive seen it work ...

[David34]

So it’s built into VR?

[MEGAMIKE]

yes but u need to trigger it externaly like a drumachine trigger 1.5v with a program..so eg; if you want to put 3 songs on one side there will be 2 triggers on your DAW...you cannot do lead in or out..do u have this rca mono plug on the back?

[okpanda]

this is interesting! so it sounds like souri's groove distance controller might not necessarily be required if you can program it yourself. you would just need something like an amplitude follower outputting cv and a digital delay for adjusting the original signal to match the latency of the width changes.

[MEGAMIKE]

yes correct ..from memory Fritz said it was added for reel to reel implementation....all that plug does is it disengages from the controller and the motor runs at its own rpm..but if souri has made one ? then get it .

[markrob]

Hi,

I believe the jack breaks the connection to the voltage adjustment pot for an LM317 voltage regulator. If you apply a voltage (Vin) to this jack, the regulator will output a voltage to the motor (Vout) such that Vout = Vin + 1.25V. Hope that helps.

Mark

[MEGAMIKE]

Thankyou mr Robinson. You are by far the most highest of lathe trolls..

[David34]

Fantastic! Think we’re going to have a go at this..

To be continued!!

[markrob]

Hi,

To see I am correct, you should be able to test using a variable DC bench supply. Make up a cable with a male phono jack and wire the center pin to the positive terminal of the supply and the negative to the shell. Measure the motor voltage terminals as you adjust the voltage from zero to the max motor voltage (IIRC 12Vdc ). See if the motor voltage is 1.25V above the power supply as you vary the voltage. To be safe, start with the supply voltage at zero and perhaps wire a 1K ohm resistor in between the power supply positive terminal and the phono jack center conductor. This will limit the current to a low level just in case (you will need to remove this later). I don't have a VR but IIRC, the front panel pot is tied to this jack. When you remove the shorting plug the circuit is opened (see the attached schematic). You probably should trace this out to make sure I've got this correct. You may need to have the front panel pot fully CCW to remove it from the circuit since the 240 ohm resistor has about 5ma. of current flowing from the output to the junction of R2 (the pot).

Regulator.jpg

[handcut]

This is great! Love the idea of having an envelope follower driving the voltage regulator.

I know a guy who builds modular synths, so I'm going to see if we can knock something up between us and will share the findings... I'm thinking the env. follower would need to be driven by a summed and low-pass filtered signal, since it's only really laterally cut low frequencies we are interested in??

[David34]

Great .. Loving the responses.. Keep them coming!

[trailerparkjesus]

I am really excited about this thread!

BUT.... does that port only allow two options, follow the LPI pot or function at full speed?

[okpanda]

If you apply a voltage (Vin) to this jack, the regulator will output a voltage to the motor (Vout) such that Vout = Vin + 1.25V.

if this is accurate and i understand it correctly, then as voltage is increased from 0 to 1.25v, the motor would gradually slow down from maximum speed to a stop.

[markrob]

Hi,

If you apply 0 Vdc into control port, the regulator will output 1.25V to the motor. If the maximum desired motor voltage is, for example 12 Vdc, then you would apply 10.75 Vdc to the control port. It is possible to adjust the output down to 0 Vdc, but it would require a -1.25 Vdc input to the control port. Hope this makes sense.

Mark

[okpanda]

yeah sorry i'm reading it again now that i am more awake and what i wrote doesn't make any sense! but ok, so that means ~10.75v would be max voltage / speed and minimum LPI?

[markrob]

Hi,

Yep! I'm not sure if the motor is expected to operate over the 100:1 or more speed range needed to run all LPI's e.g lead-in's and lead-out up to 300 lpi during cutting.

Mark

[boryo]

I am really excited about this thread!

BUT.... does that port only allow two options, follow the LPI pot or function at full speed?

I'm also curious about that. Is it possible to make variable pitch by using this port?

Thanks,
Bob

[HannesFTL]

Doe the Souri one also works using this rca female? Or does is replace the mainunit motor driving wise?

[David34]

Any updates on this?