The relays come in many voltages but it is the drive circuitry that need lower voltage.
The ICs need 5 volts so would still need 5 volt reg on board unless there are CMOS versions of all the chips, but no reason why the on-board AC transformer can't be removed and an external AC or DC power supply connected to the transformer output pads. The 5 volt reg would have to drop the extra volts so a 12 vdc would be better.
The ICs need 5 volts so would still need 5 volt reg on board unless there are CMOS versions of all the chips, but no reason why the on-board AC transformer can't be removed and an external AC or DC power supply connected to the transformer output pads. The 5 volt reg would have to drop the extra volts so a 12 vdc would be better.
Design wise anything is possible but you have to look at the cost vs benefit. The transformer is one of the most expensive single items on the board but if you redesign for higher voltage then will the parts replacing it be cost effective. I can't see a wall wart and another switching regulator being a similar cost trade off.
Also, if you have some parts running at 24v and some at 5v then you have to make sure they can interface together to do their jobs. It would be better to design for everything to run at the same voltage. Although I have used 5v and 3.3v on the same board in another design where the some of the oscillators needed 3.3v but fed there output to 5v counter/dividers, and that was a proper level change.
Also, if you have some parts running at 24v and some at 5v then you have to make sure they can interface together to do their jobs. It would be better to design for everything to run at the same voltage. Although I have used 5v and 3.3v on the same board in another design where the some of the oscillators needed 3.3v but fed there output to 5v counter/dividers, and that was a proper level change.
Well the house I am building has drywall, another 3 or 4 months and I should have a real sound room. In the mean time I have made a revision to the main board replacing the U18 discrete one shot with a real one shot chip. Everything looks good but until I have a chance to turn PCBs and test it I will hold release of the gerbers. The current main board works fine but being an engineer I can't leave well enough alone. 
The current Main Board V4 with the decoupling cap locations is a step up from the V3 board but the V3 works fine as do the other latest versions of the boards. A version 5 of the main board with a technical but not functional improvement will be tested and gerbers released when I finish building my house and have time to turn the PCB and populate it just to verify the U18 chip change.
johnhenryharris:
I've been following your Preamp Control thread from the beginning, wondering about the hubris of suggesting a different, less complex design. Your recent posting of an input selection and mute-only variant has emboldened me.
Would you consider offering the following version of your Preamp Control system:
Anything else that could be done to make the main pcb more compact would be helpful (subject to avoiding SMD parts - have pity on the elderly amongst us). I trust that this version wouldn't conflict with your agreement with PBN Audio, and suspect that you'd find a truly appreciative audience here at diyAudio.
Regards,
Scott
I've been following your Preamp Control thread from the beginning, wondering about the hubris of suggesting a different, less complex design. Your recent posting of an input selection and mute-only variant has emboldened me.
Would you consider offering the following version of your Preamp Control system:
- Single-ended only (yes, I understand that the current version can be run single-ended, but the main board is very large; fewer parts would help to reduce its size);
- Up to four inputs (I venture that most people don't need six inputs and, again, fewer inputs means fewer parts and a smaller footprint);
- Power supply removed to a separate pcb (giving users additional flexibility); and,
- If possible, a remote control system that could make use of currently available remote control handsets (e.g., RC5 or Apple handset).
Anything else that could be done to make the main pcb more compact would be helpful (subject to avoiding SMD parts - have pity on the elderly amongst us). I trust that this version wouldn't conflict with your agreement with PBN Audio, and suspect that you'd find a truly appreciative audience here at diyAudio.
Regards,
Scott
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Hi Scott,
I have made such a board, it is still balanced but you can populate only part of the main board. It still has six inputs. But it breaks the board into three: main, display and PS, and they are much smaller. See:
Input Selection and Muting - Interested
If that doesn't do it for you I could make a single ended and four input board, the other two would remain the same.
Let me know if this works for you.
Thanks,
John
I have made such a board, it is still balanced but you can populate only part of the main board. It still has six inputs. But it breaks the board into three: main, display and PS, and they are much smaller. See:
Input Selection and Muting - Interested
If that doesn't do it for you I could make a single ended and four input board, the other two would remain the same.
Let me know if this works for you.
Thanks,
John
johnhenryharris:
Yes, that Input Selection / Mute post is what encouraged me to suggest a single-ended version of your larger Preamp Control system. If the size of the Preamp Control board is largely dictated by the attenuator and if making the attenuator single-ended would not materially reduce the size of that pcb, then my suggestion doesn't make much sense. But if a single-ended board with an attenuator and just four inputs would be markedly smaller than the Preamp Control board, then that might prove very attractive.
Thanks for offering to consider designing a single-ended four input board which could be added to the two smaller boards in your Input Selection / Mute project! Would it be crazy of me to wonder if it is possible to add a single-ended attenuator to that new board?
Just wondering... ...and thanks for your consideration!
Regards,
Scott
Yes, that Input Selection / Mute post is what encouraged me to suggest a single-ended version of your larger Preamp Control system. If the size of the Preamp Control board is largely dictated by the attenuator and if making the attenuator single-ended would not materially reduce the size of that pcb, then my suggestion doesn't make much sense. But if a single-ended board with an attenuator and just four inputs would be markedly smaller than the Preamp Control board, then that might prove very attractive.
Thanks for offering to consider designing a single-ended four input board which could be added to the two smaller boards in your Input Selection / Mute project! Would it be crazy of me to wonder if it is possible to add a single-ended attenuator to that new board?
Just wondering... ...and thanks for your consideration!
Regards,
Scott
So cutting the attenuator section to single ended would reduce the board by a couple of inches. moving the PS to another board would save another couple inches. But the control circuitry for the attenuator would be the same for single ended or balanced. So while some size reduction could be done it would definitely be a new layout.
Things to play with when things slow down at work.
I had thought about making the main board in two or three sections and stacking them so you have a tighter package for different circumstances.
Things to play with when things slow down at work.
I had thought about making the main board in two or three sections and stacking them so you have a tighter package for different circumstances.
johnhenryharris:
That's the key takeaway. Thanks for your consideration!
Regards,
Scott
Now that I have posted the gerbers in the other thread for the boards with just input selection and mute, 6 input balanced. Will start to work on a version that is single ended, 4 input with remote. So the display board will be the same. Will break the PS off to another board and may do 2 boards for the main, one analog one digital, with a ribbon cable between so they can be stacked if needed to save space.
I haven't posted the gerbers as I haven't tested the updated circuit yet, other then the same one-shot circuit being used in another project that worked well. I can post the gerbers just as I did with the updated remote awhile back which didn't get tested until someone turned some boards and I built one and it worked well. In a day or so I should have time to generate the gerbers and post them.