In case it helps you Rick I used this one :
FSM8JH - TE CONNECTIVITY / ALCOSWITCH - SWITCH, SPST, 0.05A, 24VDC, PCB | element14 Australia
FSM8JH - TE CONNECTIVITY / ALCOSWITCH - SWITCH, SPST, 0.05A, 24VDC, PCB | element14 Australia
Any pictures
I know this was last year's project or the year before that.
But, do we have any pictures from the DIY'ers that built the VCPre and how you are using it? As a stand-alone preamp? Incorporated it into a power amp to make an integrated? It's always nice to see the finished product. Pictures always inspire me.
I know this was last year's project or the year before that.
But, do we have any pictures from the DIY'ers that built the VCPre and how you are using it? As a stand-alone preamp? Incorporated it into a power amp to make an integrated? It's always nice to see the finished product. Pictures always inspire me. 
Rick, find attached 2 pictures.
I have incorporated a VCPre into my FC-100 amplifier and made it an integrated amplifier.
Since some time I have been working on integrating the VCPre into a stand-alone PRE-amplifier.
But since the VCPre (its LDRs) is not able to drive a long pair of RCA-cables and (or) a low-impedance amplifier, I decided to connect the VCPre's output to a buffer.
I have chosen Calvin's buffer.
This buffer is very sensitive to the supply voltages (+/-18VDC).
My standard LM317/LM337 PSU is showing a ripple of about 1.5mV at 100mA output current. This ripple is big enough to introduce hum to the amplifier.
I am currently working on a LM3x7 - tracking-pre - regulator solution as power-supply, which - as I hope - will reduce the amount of ripple to some hundred µV.
If even this solution won't work satisfactorily, I will think this project over again.
Best regards - Rudi
I have incorporated a VCPre into my FC-100 amplifier and made it an integrated amplifier.
Since some time I have been working on integrating the VCPre into a stand-alone PRE-amplifier.
But since the VCPre (its LDRs) is not able to drive a long pair of RCA-cables and (or) a low-impedance amplifier, I decided to connect the VCPre's output to a buffer.
I have chosen Calvin's buffer.
This buffer is very sensitive to the supply voltages (+/-18VDC).
My standard LM317/LM337 PSU is showing a ripple of about 1.5mV at 100mA output current. This ripple is big enough to introduce hum to the amplifier.
I am currently working on a LM3x7 - tracking-pre - regulator solution as power-supply, which - as I hope - will reduce the amount of ripple to some hundred µV.
If even this solution won't work satisfactorily, I will think this project over again.
Best regards - Rudi
Attachments
Gentlemen,
since all the functions (Power On/Off, attenuation, source selection, ...) of my PRE can be controlled via a remote control unit, I do not need a switch, neither do I need a knob on the front panel.
This is the reason why I have currently installed the motorized dual potentiometer right into the case (see attached image 1).
But this potentiometer looks like (is) a real anachronism, and I would like very much to replace it by a "digital potentiometer" (MCP4151, which has 128 wiper steps) followed by a VCCS (see attached image 2).
I have already done a layout for this schematic and have etched and populated two of the resulting PCBs (see attached image 3).
I am using simple LEDs instead of LDRs on this "evaluation-PCB".
My problem: I am no good at programming a PIC - µProcessor in "C".
I have been programming IBM-mainframes in Assembler for more than 35 years of my life, but now, when I program a PIC in "C", I get lost and desperate, if I forgot to insert a ";" or a "}" into the code.
I am of course able to change the existing VCPre's code (whose inital programming has been done by METAL), if required, but implementing a new function, ...?
If there is anybody among you, who has the time to assist me, who knows the internals of the PIC16F887 and has a PIC-evaluation board and who knows, how to program it in "C" (for example the SPI-interface):
I will happily send him one of the two evaluation PCBs and will program together with him the digital potentiometer interface.
And of course I will send him a couple of the resulting Pre - PCBs.
Best regards - Rudi_Ratlos
since all the functions (Power On/Off, attenuation, source selection, ...) of my PRE can be controlled via a remote control unit, I do not need a switch, neither do I need a knob on the front panel.
This is the reason why I have currently installed the motorized dual potentiometer right into the case (see attached image 1).
But this potentiometer looks like (is) a real anachronism, and I would like very much to replace it by a "digital potentiometer" (MCP4151, which has 128 wiper steps) followed by a VCCS (see attached image 2).
I have already done a layout for this schematic and have etched and populated two of the resulting PCBs (see attached image 3).
I am using simple LEDs instead of LDRs on this "evaluation-PCB".
My problem: I am no good at programming a PIC - µProcessor in "C".
I have been programming IBM-mainframes in Assembler for more than 35 years of my life, but now, when I program a PIC in "C", I get lost and desperate, if I forgot to insert a ";" or a "}" into the code.
I am of course able to change the existing VCPre's code (whose inital programming has been done by METAL), if required, but implementing a new function, ...?
If there is anybody among you, who has the time to assist me, who knows the internals of the PIC16F887 and has a PIC-evaluation board and who knows, how to program it in "C" (for example the SPI-interface):
I will happily send him one of the two evaluation PCBs and will program together with him the digital potentiometer interface.
And of course I will send him a couple of the resulting Pre - PCBs.
Best regards - Rudi_Ratlos
Attachments
Rudi I have probably one hundred or so of AD5206 boards with uprocessor and remote controls. You can have the pic choose inputs, turn on and off, mute, balance, up/down, on and off. I can sell these to you at a reasonable price if you want or you could try one and see what you think. There is an endless supply in a sense as my vendor has told me he will program more for me if I need. I have 100k, 50k and 10k but of course with 6 digipots per chip you can parallel to come up with many different values. I would do that and then also put a trimmer across the whole thing to add a parallel resistance to reduce the total value to whatever my perfect value was. It works well and you are welcome to try. I have the remotes, power supplies and IR modules as well.
Uriah
Uriah
Look at this very quick demo video Rudi, this is what I just proposed to you to do when we first started this project back in 2013, just use a digi pot, I tried it already back in DEC 2012. Anyway, the initial setting is at volume max, I just press down button to lower the volume, look how the upper LED fades and the lower LED brightens..
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METAL: I am very, very pleased having received your post!
Please: give me your address (via PM), and I will send you my evaluation PCB in a minute!
I am able to adjust the quiescent current of my current SYMASYM_PCB (see attached image), but when I want to "marry" it to my (your) PRE: it is saying that " Startup.as." is missing!
I feel very happy that you have answered my post!
You are the very best to assist me!!
Best regards - Rudi_Ratlos
Please: give me your address (via PM), and I will send you my evaluation PCB in a minute!
I am able to adjust the quiescent current of my current SYMASYM_PCB (see attached image), but when I want to "marry" it to my (your) PRE: it is saying that " Startup.as." is missing!
I feel very happy that you have answered my post!
You are the very best to assist me!!
Best regards - Rudi_Ratlos
Attachments
I am very happy that METAL is "on board" again!
Together we will get rid of the motorized analog dual-potentiometer (which is imprecise, costs a lot, ...is an anachronism) and will replace it by a laser-trimmed dual digital MCP42100 potentiometer (being followed by a VCCS).
The MCP42100 will give you 256 (!) wiper steps for both inline potentiometers!
I have attached two images of our current progress.
We are working hard on it!
Be sure: this will be one of the best-sounding, very well-priced and versatile PREs that you have ever listened to!
It will take some time though. Neither METAL nor me are in a hurry.
Best regards - Rudi_Ratlos
P.S.: The software (the PIC's firmware) to be programmed (will be done by METAL) is the biggest part for a successful implementation!
Together we will get rid of the motorized analog dual-potentiometer (which is imprecise, costs a lot, ...is an anachronism) and will replace it by a laser-trimmed dual digital MCP42100 potentiometer (being followed by a VCCS).
The MCP42100 will give you 256 (!) wiper steps for both inline potentiometers!
I have attached two images of our current progress.
We are working hard on it!
Be sure: this will be one of the best-sounding, very well-priced and versatile PREs that you have ever listened to!
It will take some time though. Neither METAL nor me are in a hurry.
Best regards - Rudi_Ratlos
P.S.: The software (the PIC's firmware) to be programmed (will be done by METAL) is the biggest part for a successful implementation!
Attachments
This is great news Rudi! I have a proposal and a question. The proposal is to put also two switch to be able to adjust volume manually not only from remote control.
This digital pot will be like a retrofit module for the old preamps or will be a completely new version of preamp with relays and everything ?
This digital pot will be like a retrofit module for the old preamps or will be a completely new version of preamp with relays and everything ?
Adrian: there will be no knobs neither switches on the front-panel of my SYMASYM's case!
I like to sit in my armchair and do everything via remote-control!
The "new R_PRE-PCB" will no longer support an analog motorized potentiometer with Motor- H-bridge.
We have entered the 3rd millenium - didn't we?
Kind regards - Rudi_Ratlos
I like to sit in my armchair and do everything via remote-control!
The "new R_PRE-PCB" will no longer support an analog motorized potentiometer with Motor- H-bridge.
We have entered the 3rd millenium - didn't we?
Kind regards - Rudi_Ratlos
Attachments
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I know I was late to the VCPre party, but I had much bigger projects to deal with over the past 18 months. And since I'm slow and meticulous, and still work full-time, it takes me many, many evenings and weekends to complete a project.
So, what exactly is the difference between a pre-amp and a buffer? Or, are they essentially the same? I gather from reading they are the same. I don't have long interconnects between my gear so would the VCPre be enough of a pre-amp to use. BTW, I built the Doug Self preamp a couple of years ago when it was featured in Elektor, which I use in my main system, but I have other amps where I want to use the VCPre.
I've read much on the B1 Buffer Salas and have order the PCB for it along with the parts. Could I use the VCPre to feed the B1 buffer like you did with the Calvin? Are there any benefits of doing so aside from allowing longer RCA interconnect runs? I would still use the VCPre as the signal switcher over the manual method used on the B1.
My next big project is your Symasym amp with the newest digital pre as an integrated amp. Would this be a good project to incorporate the B1 Buffer? I will start on the Black Beauty PCB soon.
Thanks for all you hard work on these projects!
Rick
Motorized VC
Is the motorized volume control designed to be used manually as well? If so, does it need to be energized? I tried to manually rotate the shaft on one of Bourns I got for the VCPCre and it's very, very stiff. Near impossible to move, or move smoothly for sure. Does energizing it free up the gears or something?
Is the motorized volume control designed to be used manually as well? If so, does it need to be energized? I tried to manually rotate the shaft on one of Bourns I got for the VCPCre and it's very, very stiff. Near impossible to move, or move smoothly for sure. Does energizing it free up the gears or something?
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