I've just spent most of the past two days laying out an IR receiver board to work with my main board. This is not a cable-connected board, rather it is an extension to the main board -- it has pins on one side that match the Euro-style screw terminals on the main board, and then duplicates the main board terminals on the other side and adds connections for motor-driven pots and the IR receiver. For now, the functions are volume up/down, balance left/right, and mute.
The IR board adds 1.25 inches to the length of the main board to make the total assembly including IR board 2.5 inches by 4.5 inches, and contains the processor chip to handle logic and a dual H-bridge chip to control power to the pot motors. The chip can handle up to 600ma per motor, and the pots I have in mind require a maximum of 100ma to operate.
Most of the software required is already out there and I don't intend to reinvent the wheel; I need to wire up a breadboard and see how this thing works, then it'll be time to order a few boards to test the prototype.
I have a question to put to folks: I've designed this first control to match what I'd personally like in the way of controls, I like mechanical pots and thus my first IR control is mechanical pot based. What kind of control would most people prefer? I realize that everyone will have a different opinion so I'm not asking for your own personal preference -- I'm asking for a consensus of what most audiophiles would enjoy most.
Controls could be -- in additional to motorized -- a digital pot or a capacitive touch-based or mechanical button panel, for example.
My design is pretty flexible, as of now volume and balance are controlled by a voltage between 0 and 5V, the mute is a momentary press on a button to set a pin high, so it could have practically any front-end someone would want to add to it.
The IR board adds 1.25 inches to the length of the main board to make the total assembly including IR board 2.5 inches by 4.5 inches, and contains the processor chip to handle logic and a dual H-bridge chip to control power to the pot motors. The chip can handle up to 600ma per motor, and the pots I have in mind require a maximum of 100ma to operate.
Most of the software required is already out there and I don't intend to reinvent the wheel; I need to wire up a breadboard and see how this thing works, then it'll be time to order a few boards to test the prototype.
I have a question to put to folks: I've designed this first control to match what I'd personally like in the way of controls, I like mechanical pots and thus my first IR control is mechanical pot based. What kind of control would most people prefer? I realize that everyone will have a different opinion so I'm not asking for your own personal preference -- I'm asking for a consensus of what most audiophiles would enjoy most.
Controls could be -- in additional to motorized -- a digital pot or a capacitive touch-based or mechanical button panel, for example.
My design is pretty flexible, as of now volume and balance are controlled by a voltage between 0 and 5V, the mute is a momentary press on a button to set a pin high, so it could have practically any front-end someone would want to add to it.
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Here is a picture of the prototype that I used to develop the software. The 25-cent piece gives you an idea of the diminutive size of the board, considering it contains all the processing power and precision drive components for a full stereo volume/balance control. The main board is the part between the two sets of mounting hardware, the board to the right of the brass knobs is actually a daughterboard not used during operation.
Two one-turn pots and pushbutton on left panel are for volume, balance, and mute; the third pot is a 10-turn pot which I can switch into the circuit for precisely viewing small changes to data values as the circuit runs.
The very thin (.5 inch wide) board attached to the output side of the main board on the right is the daughterboard that is required to be connected during the calibration cycle.
Calibration time, by the way, has been increased from 7 minutes to about 20 minutes -- this greatly increases confidence in the result of the calibration. This circuit produces virtually no heat and current is limited to about 10ma maximum per device, so aging of the LDRs will be slow if it happens at all. The mute circuit will kill sound with 2ma going through the shunt LDRs and zero current through the series devices, so muting the circuit will not age the LDRs.
The power supply has been extensively modified and in the next iteration won't look as it does in this picture.
All connections are via Euro-style screw terminal that will accept wire or pin connections. The calibration daughterboard and the IR daughterboard (to be attached to the left side) both have in-built pins that exactly match the main board connectors so that there will be no fiddling with individual wires or cables to connect them.
Two one-turn pots and pushbutton on left panel are for volume, balance, and mute; the third pot is a 10-turn pot which I can switch into the circuit for precisely viewing small changes to data values as the circuit runs.
The very thin (.5 inch wide) board attached to the output side of the main board on the right is the daughterboard that is required to be connected during the calibration cycle.
Calibration time, by the way, has been increased from 7 minutes to about 20 minutes -- this greatly increases confidence in the result of the calibration. This circuit produces virtually no heat and current is limited to about 10ma maximum per device, so aging of the LDRs will be slow if it happens at all. The mute circuit will kill sound with 2ma going through the shunt LDRs and zero current through the series devices, so muting the circuit will not age the LDRs.
The power supply has been extensively modified and in the next iteration won't look as it does in this picture.
All connections are via Euro-style screw terminal that will accept wire or pin connections. The calibration daughterboard and the IR daughterboard (to be attached to the left side) both have in-built pins that exactly match the main board connectors so that there will be no fiddling with individual wires or cables to connect them.
Attachments
Very nice indeed - complete as a 'stand-alone' item, with the option of additional remote control - complete module, nice and simple - love it!
The input/output plugs just attach where the calibration board is plugged in, as per the right hand connector in the photo, yes?
Does the remote control board use the main power supply, or have it's own regulator, etc,
?
The input/output plugs just attach where the calibration board is plugged in, as per the right hand connector in the photo, yes?
Does the remote control board use the main power supply, or have it's own regulator, etc,
?
Very nice wapo. I've been following this thread since its start. I'm more of a simple circuit guy and stay away from micro controllers as much as I can. I've implemented a lot of those same features in my relatively simplistic LDR attenuator as well. I control the LDRs with current and limit the LDRs to about 10ma as well. I built a computerized LDR tester (16 bit ADC and USB interface) and can test about 320 a day if I'm working hard. In my experience, I've found that they settle down in value very quickly, maybe to within 95% of their final value in a second or two, and to 99.99% within 10 seconds. Mine uses a simple 10k linear pot for control, but with careful component and circuit selection, I get a nearly perfect log function. The only downside is the high output impedance.
@James, yes, to switch from calibrate to operate you move one jumper and remove the calibrate daughter board and connect the input/output wiring in its place. Best to use a row of pins and connect i/o wiring to the pins as I have done for the pots and mute in the photograph -- that way you don't have to worry about getting wires in the right order, you just wire the solid block of pins and the wires are automatically correct.
The remote board uses the +5V regulator on the main board for the PIC on the wireless board and the logic part of the driver chip. The motor drive power comes from a separate regulator on the IR board, and that's easy to implement because when the IR daughterboard is attached the DC IN connector moves from the main board to the IR board (all the connectors on the main board are duplicated on the IR board).
That's a neat idea about connecting the in/out plugs - looks like you've just about covered everything
As the calibration is an occasional thing, would it be possible to put a row of blank holes along the front side (in the photo) of the pcb to 'plug it in' (storage) when not in use - I tend to put things like this 'in a safe place' and totally forget where I've put them - maybe other people might have the same problem ...
Are you any closer to finalising your ideas about making these units and/or kits?
Alan Flores (Warpspeed Vol Control) stopped supplying kits after a few guys suffered assembly problems and now is only supplying finished items, and this might be something to keep in mind too as the ldrs are quite sensitive to the hot soldering iron
As the calibration is an occasional thing, would it be possible to put a row of blank holes along the front side (in the photo) of the pcb to 'plug it in' (storage) when not in use - I tend to put things like this 'in a safe place' and totally forget where I've put them - maybe other people might have the same problem ...
Are you any closer to finalising your ideas about making these units and/or kits?
Alan Flores (Warpspeed Vol Control) stopped supplying kits after a few guys suffered assembly problems and now is only supplying finished items, and this might be something to keep in mind too as the ldrs are quite sensitive to the hot soldering iron
@James, that's a neat idea about creating a storage location for the calibration board, and easily implemented on this particular board because there is enough space (no promises for future boards). I've dropped pads on the board to solder in plugs for enough of the pins at the ends and the center to hold the board securely. It'll add something to the cost of parts and manufacturing but I daresay not much.
I found and read some of the threads out there on the Flores Warpspeed, and it seems that he stopped offering kits in 2010 and right now no longer offers the fully made systems, either. I don't know if he'll get back to it. If my information is old and he's back at it, please let me know.
Re the kit vs ready-made, if by "kit" you mean the boards not built into a case then, definitely yes. The Flores kit looked to me like the main circuitry was entirely potted and the only thing left to do was a dozen or so connections for in-out plugs, power, volume control, etc.
If, however, by kit you mean a board and the components to be installed in pieces, I'd have to think long and hard, and it won't happen until I am very sure that the board is entirely without a design flaw that could rear up and bite a builder. My main board contains somewhere around 60 components as I recall, and it is not a trivial board to build (for example, the resistors are 1/8 watt grain-of-rice sized and hard to deal with) and I don't want a reputation for offering kits that people could describe as too hard to build.
I've been there myself and haven't forgotten the nasty sinking feeling when I'd spent hundreds of dollars for a kit, built it, and plugged it in to discover it didn't work and now I have to figure out what's wrong. Worse, sometimes I was skilled enough to build it but not skilled enough to troubleshoot it, and troubleshooting this particular board is going to require knowledge of both digital and analog circuits. I think there are not many out there who could do that. Any thoughts?
offering a "kit of bits" will require a very comprehensive Build Guide
And knowing what a codswallop of an effort many of our Members make of assembly I would find it hard to go to bed with a clear conscience.
Think carefully before you "sell Kits".
But if you were to offer a selection of difficult to obtain components that are adequately labeled with an accurate layout/guide then the responsibility could/should be transferred to the competent buyer for correct assembly.
And knowing what a codswallop of an effort many of our Members make of assembly I would find it hard to go to bed with a clear conscience.
Think carefully before you "sell Kits".
But if you were to offer a selection of difficult to obtain components that are adequately labeled with an accurate layout/guide then the responsibility could/should be transferred to the competent buyer for correct assembly.
I think the main problem with Alan's kits was that the ldrs themselves required soldering and many people that have had years of soldering experience still have a very vague understanding about the care that heat sensitive components require and small metal heatsink clips are pretty much unknown these days - not sure why.
Anyway, we have a few of Alan's 'kits' out here and despite the reminders to 'clip the legs', one turned out to be 'less than perfect' - never did get to the bottom of it - assumed it was 'ldr abuse' but might have been faulty ldrs, I suppose - it just wasn't as clear as the other ones and sounded similar to Georges original units.
We have a few of Uriah's kits here too and 'no problems', apart from sorting out the assembly instructions - the 'audio group' in Singapore also have a number of Uriah's units and don't experience any problems that I've read about - maybe some confusion about setting up the input & output impedances ....
Another thing occurred to me that might be useful - a few years ago I got one of those pic controlled ladder volume controls from the guys at 'Twisted Pear' and just carefully followed the excellent instructions to assemble the unit and even after degugging the unit (extreme frustration!), wasn't ever really comfortable about it's operation as I've quite limited understanding about those 'pic things' (didn't 'get into' those 'Aduano things' either)
After all this rambling about, as your units are much more complicated than any of these, it's pretty obvious that complete board assembly (and finished testing) would be the only way to go, from my perspective anyway, and I'm quite willing to pay the much higher cost of getting a fully tested product.
So, I'd advise to make/sell the complete boards and include the pots, switches, etc and maybe even include some wire, maybe even 'pre-cut' ('value added' by the manufacturer, if you 'get my drift') - also, maybe some 'stick-on' pcb standoffs for the pcb to simplify chassis assembly, and so on to make the assembly a really easy experience.
Or perhaps, an option of assembled & tested pcb only with pot, or the full, all inclusive package - probably depends on how much time you have to spare with this sort of 'mail ordering' stuff.
A contentious subject but I went thru a period where I 'went nuts' on rca phono plugs for these units - even tried some of those crazy priced WBT units (the irritating things DO come loose with use, damnit!) and ended up with some inexpensive copper ones from China that screw on from the outside of the chassis (so can solder/assemble/test the sockets, etc before inserting into the chassis)
How do you feel about developing a 10kR antilog pot (dual, 100R <-> 10kR) - virtually unobtanium these days - required for Thorsten L's u-beaut tone control module design - can't find anyone doing even a 12/23 position stepped version ....
Anyway, we have a few of Alan's 'kits' out here and despite the reminders to 'clip the legs', one turned out to be 'less than perfect' - never did get to the bottom of it - assumed it was 'ldr abuse' but might have been faulty ldrs, I suppose - it just wasn't as clear as the other ones and sounded similar to Georges original units.
We have a few of Uriah's kits here too and 'no problems', apart from sorting out the assembly instructions - the 'audio group' in Singapore also have a number of Uriah's units and don't experience any problems that I've read about - maybe some confusion about setting up the input & output impedances ....
Another thing occurred to me that might be useful - a few years ago I got one of those pic controlled ladder volume controls from the guys at 'Twisted Pear' and just carefully followed the excellent instructions to assemble the unit and even after degugging the unit (extreme frustration!), wasn't ever really comfortable about it's operation as I've quite limited understanding about those 'pic things' (didn't 'get into' those 'Aduano things' either)
After all this rambling about, as your units are much more complicated than any of these, it's pretty obvious that complete board assembly (and finished testing) would be the only way to go, from my perspective anyway, and I'm quite willing to pay the much higher cost of getting a fully tested product.
So, I'd advise to make/sell the complete boards and include the pots, switches, etc and maybe even include some wire, maybe even 'pre-cut' ('value added' by the manufacturer, if you 'get my drift') - also, maybe some 'stick-on' pcb standoffs for the pcb to simplify chassis assembly, and so on to make the assembly a really easy experience.
Or perhaps, an option of assembled & tested pcb only with pot, or the full, all inclusive package - probably depends on how much time you have to spare with this sort of 'mail ordering' stuff.
A contentious subject but I went thru a period where I 'went nuts' on rca phono plugs for these units - even tried some of those crazy priced WBT units (the irritating things DO come loose with use, damnit!) and ended up with some inexpensive copper ones from China that screw on from the outside of the chassis (so can solder/assemble/test the sockets, etc before inserting into the chassis)
How do you feel about developing a 10kR antilog pot (dual, 100R <-> 10kR) - virtually unobtanium these days - required for Thorsten L's u-beaut tone control module design - can't find anyone doing even a 12/23 position stepped version ....
James, you made me wonder about the benefits of putting the LDR control and IR circuitry on one board and gave it a try since the connections were already lined up to enable easy bolt-together assembly.
In the end after considerable rearranging of parts to take advantage of open spaces, I got a 2.5" x 4.0" board -- gained only half an inch off the two-board solution. Not good enough to tip the balance away from the flexibility of two boards which make it possible later to use a variety of front-end controls with the main board. I think it's likely that a variety of control solutions will evolve before there will be a need to modify the LDR control board.
On the other question -- you're talking about a pot with the opposite slope of a conventional volume control to be used in a tone control section? Where can I see the complete circuit?
No -- they are motorized pots, and the IR controls the pots themselves. I really like the look & feel of pots, I don't much care for buttons.
An encoder is also doable, perhaps include both via jumper select in a future version, but not together because your concern would play in that scenario.
I'd recommend against kits, because a ready to go tested board will already give you enough problems with user assembly.
This seems to be the consensus, and it definitely works for me -- I want to be responsible only for boards that went out the door in working condition. This is how I'll proceed. Thanks to the folks who commented on this issue.
It would be best for no user soldering to the board at all, just connectors. You would not believe how badly soldering can be botched up.
That is, in fact, the way the board is presently configured. Right now I'm scratching my head over how to design the LDR attachment to the board -- I am loathe to put another connector into the signal path, and anything short of soldering the LDR to the board will, in fact, put another connector in the signal path.
I have a compromise in mind that will protect the board from multiple soldering and unsoldering operations into through-hole solder points while avoiding the potential degradation of unsoldered contacts. My first boards will have this approach, I think. We shall see.
I thought that the ldr input/outputs are on the green terminal blocks. It would be nice to have the audio circuit all soldered, though.
One way would be to mount the RCAs on the board.
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