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Remote Volume Control/ Motorized Pot

Judas Priest

Judas Priest

Super Member
I want to add a remote to control the volume on my DIY preamp.

Can someone point me in the right direction? I know I need a motorized pot, but how do I control it with a universal IR remote?
 
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Judas Priest said:
I want to add a remote to control the volume on my DIY preamp.

Can someone point me in the right direction? I know I need a motorized pot, but how do I control it with a universal IR remote?
Click to expand...
That a great question?
I’d be following this thread?
Bobhorn
 
Ya, some can be noisy. I've seen some with the motor mounted at the back of the chassis with a shaft running to the pot on the front. It seems that setup may help reduce motor noise from having the motor mounted at the back of the pot.
 
My remote board came a few days ago, and since I am planning on replacing the Chinese "Alps" pot with a real one, I have a question.

The circuit turns the volume all the way down, and then to the 9 o-clock position with every start up. The pot on the board has 8 pins, but the 2 extra ones don´t seem to be connected to anything. My question is, how does the board know in what position the pot is. How does it know when the 6 o-clock position is reached, and then the 9 o-clock position?

There are 2 chips on the board, an STC 15W104 which seems to be some kind of (edit) programmable memory chip, and an L911OS, which is a motor controller.

I´m hopeing the board just tells the motor to go the one direction for a certain amount of time to reach 0% and then again for a certain amount of time to reach 25%. But I don´t think that´s how it works, because if the pot was at 100% at start up, it would take much lomger to reach 0%. Or does the motor controller sense an increase in motor current when the 0% position is reached?

I could just leave the pot on the board and use it, but I´m afraid it might impair the audio quality.
 
Last edited:
Where was the volume set at when you turned it off? Maybe the memory chip returns it to the volume it was at when turned off? With the extra connections it makes you wonder if one will.set it to zero at start up. Without a schematic it would be hard to tell though.
 
Noticed that in one review the guy complained that the device goes to zero when turned on then advances to the
9 O’clock position every time and can’t be changed, but that the remote control worked very smoothly after that initial response.

This would be a problem for me...One possible solution, at least for my use, would be to use a separate power supply for the volume control. One could turn it on and then use the remote to go to zero prior to powering up the system.


Looking forward to the review....

Andy
 
That´s exactly what mine does; when powered on, no matter where the volume is set, it goes to 0% and then to 25%.

This doesn´t really bother me, but I could live without it. When I have a bit more time this weekend, I´ll try and get my USB scope running and see more closely how the controller drives the motor on power up at various volume settings.

I´ll keep you guys posted :)

Edit: I have a question regarding the Alps pot I will be using. Should I go with 10K or 100K ohm?

The output impedance of my DAC is 400 Ohm.
 
Please do....

would’ve already purchased a couple of them but that 9 o’cLock would wake the dead on both of my preamps (-;

Still pondering the separate power supply just for it, that may be worth the effort....
 
Probably uses motor current to sense end of travel. Thats how auto-down windows in cars work. Simple test, turn it all the way up, then power cycle it so it turns itself down. Grab the knob and prevent it from going all the way down, then see what it does. My guess is it will stop where you grab it and then try to turn back up by however much it normally does. Its probably just a program function to run the motor for however much time after it hits bottom of travel.
 
I´m hoping you´re right; I´ll see on the weekend.

@adnick: I really don´t see the problem with the 9 o clock position. It´s unnecessary but not a problem for me.

Does your system play music when you start it? I turn my system on, then choose what I want to hear. In fact, I turn on my preamp, and then the amp. So, all I have to do is turn the volume all the way down before I turn on the amp, which is what I ALWAYS do anyway :)
 
Judas Priest said:
I´m hoping you´re right; I´ll see on the weekend.

@adnick: I really don´t see the problem with the 9 o clock position. It´s unnecessary but not a problem for me.

Does your system play music when you start it? I turn my system on, then choose what I want to hear. In fact, I turn on my preamp, and then the amp. So, all I have to do is turn the volume all the way down before I turn on the amp, which is what I ALWAYS do anyway :)
Click to expand...

It’s only a problem with the tuner, one system defaults to the tuner, and it’s only a problem on it if it’s manually set to the tuner. But you’re right it’s not an issue with anything that doesn’t automatically start, CD, phono....

FM is my default still, probably one of the last of my kind (-;
 
IF the motor is a stepper motor then the controller would send enough 'steps' to get the control from 100% to 0% (no matter where it starts) then quit stepping; then it would send out just enough 'steps' to set it to 25%. No need to sense motor current or start/stop positions. Simple boot sequence to program, relatively fail safe for amps and speakers. Just MHO.
 
I tried holding the pot shaft, but the motor just keeps running. It seems to run for a pre set time to reach 0% and then a pre set time to reach 25%. I´ve been having some laptop/software problems with my USB scope, I´ll try and get some measurements as soon as I get things straightend out. I´ll probably just buy a genuine ALPS pot and see what happens.

I will be completely re building my preamp, with a new power supply, case, the whole thing.
 
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