Bear,
I think the DS1809 simply stores the vol setting when you turn off - I don't believe it can set up a table of settings. Now if there was such a chip then we could dispense with the microcontroller and just do a calibration exercise manually i.e adjust the digital pot to give LDR resistance and then store this as -10dB going up through the dB scale repeating for each resistance setting. Essentially what we want is a potentiometer which allows us to set the resistance we want at all the db settings and to store them in no-volatile memory. I think this is what Rellum did but he used a number of parts - does anybody know of one part for this? I suppose it would be called a programmable potentiometer
I think the DS1809 simply stores the vol setting when you turn off - I don't believe it can set up a table of settings. Now if there was such a chip then we could dispense with the microcontroller and just do a calibration exercise manually i.e adjust the digital pot to give LDR resistance and then store this as -10dB going up through the dB scale repeating for each resistance setting. Essentially what we want is a potentiometer which allows us to set the resistance we want at all the db settings and to store them in no-volatile memory. I think this is what Rellum did but he used a number of parts - does anybody know of one part for this? I suppose it would be called a programmable potentiometer
Yes in theory this is all possible but in practise it requires the matching of a quad of LDRs for balanced operation and matched octuplets for 4 channels,etc. You can imagine the difficulty of achieving this matching!
DS3901, DS1809, etc
I'm sure Paul has already run through all the options for this controller. He seems to be a very thorough fellow. Besides, when someone has gone to as much effort as Paul has to engineer a solution like this and then offers to share with us, second-guessing his approach or suggesting changes seems a bit rude. This isn't a collaborative effort -- Paul (and George) are graciously sharing with the rest of us.
I'm sure Paul has already run through all the options for this controller. He seems to be a very thorough fellow. Besides, when someone has gone to as much effort as Paul has to engineer a solution like this and then offers to share with us, second-guessing his approach or suggesting changes seems a bit rude. This isn't a collaborative effort -- Paul (and George) are graciously sharing with the rest of us.
Marc
I'm sorry if this is how it came across & I have already paid for a board from Paul so I'm not meaning to undermine his efforts in any way & much appreciate them.
I guess I was just thinking out loud & I'm sure Paul (& George) have considered the territory.
George provided the whole concept & released the idea to the DIY public for which we are all grateful.
Paul has introduced a good circuit for voltage controlled current source with remote control options.
I was just wondering if there might be a next step - Rellum has already done something along these lines, you realise!
I also don't see this as a second-guessing or trying to replace Paul's work rather as a possible add-on?
You might remember earlier in this thread I put together a synopsis of Paul's answers for readers because the same questions were arising regularly!
I'm sorry if this is how it came across & I have already paid for a board from Paul so I'm not meaning to undermine his efforts in any way & much appreciate them.
I guess I was just thinking out loud & I'm sure Paul (& George) have considered the territory.
George provided the whole concept & released the idea to the DIY public for which we are all grateful.
Paul has introduced a good circuit for voltage controlled current source with remote control options.
I was just wondering if there might be a next step - Rellum has already done something along these lines, you realise!
I also don't see this as a second-guessing or trying to replace Paul's work rather as a possible add-on?
You might remember earlier in this thread I put together a synopsis of Paul's answers for readers because the same questions were arising regularly!
jkeny said:
No worries. Sorry if my reflexive defense of Paul was taken the wrong way. I really like the sharing atmosphere on DiyAudio and I never want anyone creative to get annoyed. I wish that Mauro Penasa and Pedja Rogic still frequented the boards.
I probably didn't need to come to Paul's defense. Sorry for being overzealous.
And I don't mean to question either. It was just a thought that maybe it could be an addition to Paul's board to adjust individually each LDR's current and the adjustment stays in memory when powered off.
I have a couple of them and i might play with them. After all...that's what DIY is all about.
Bear
I have a couple of them and i might play with them. After all...that's what DIY is all about.
Bear
Paul is a smart guy. Great guy for sharing with us and same with George, but coming up with new ideas and questions is no crime guys. This topic has been covered previously in this thread. Its an interesting idea with no solid solution yet.
Bringing up the other DS chip is great and maybe Paul didnt see it. Thorough as I am sure he is, he probably did, but also it IS neat that its nonvolatile and if you have the skills I am sure you could make it work, but I think it would be more involved that the DS1802 and I think it would get fiddly.
I agree that questioning George endlessly about the validity of his circuit is silly, but finding other ways to implement it is cool as hell, I think. This is exactly what Paul has done. He has found another way to control it. Cool. I highly doubt offense has been taken.
If you stop asking online how will we ever know the next new idea?
Uriah
Bringing up the other DS chip is great and maybe Paul didnt see it. Thorough as I am sure he is, he probably did, but also it IS neat that its nonvolatile and if you have the skills I am sure you could make it work, but I think it would be more involved that the DS1802 and I think it would get fiddly.
I agree that questioning George endlessly about the validity of his circuit is silly, but finding other ways to implement it is cool as hell, I think. This is exactly what Paul has done. He has found another way to control it. Cool. I highly doubt offense has been taken.
If you stop asking online how will we ever know the next new idea?
Uriah
Marc,
I agree with you - we have lost too many good guys from this forum and at a great loss to the forum. We may well have done so with Steve Dunlap also - another generous individual who gave us a unique output stage design from one of his commercial amplifiers but due to constant ego parading & people asking the same questions without bothering to read the thread he got fed up. He has posted sporadically since but I'm sure he's less likely to be as giving in the future - what a shame the moderators aren't onto this sort of misbehaviour in a more timely manner
I agree with you - we have lost too many good guys from this forum and at a great loss to the forum. We may well have done so with Steve Dunlap also - another generous individual who gave us a unique output stage design from one of his commercial amplifiers but due to constant ego parading & people asking the same questions without bothering to read the thread he got fed up. He has posted sporadically since but I'm sure he's less likely to be as giving in the future - what a shame the moderators aren't onto this sort of misbehaviour in a more timely manner
Bit OT, but you mentioned and its recent to me. Check out the BantamDAC. $2 for a board and about $30 for parts. Worth a try! ITs a clone of AlienDAC. Will stop the DAC talk now But to keep it On Topic I intend to attenuate it with a Lightspeed. Should be a very clean signal all the way to the amps.
Uriah
Gonna go take a pic of the mess I am using to test. Its working but its hell. I have new jumpers on the way from Allied and hope that helps keep the 'height' of my test fixture to a minimum and out of the way of my LDRs resistor leads. Just a sec and I will show you guys
But to keep it On Topic I intend to attenuate it with a Lightspeed. Should be a very clean signal all the way to the amps.Uriah
Gonna go take a pic of the mess I am using to test. Its working but its hell. I have new jumpers on the way from Allied and hope that helps keep the 'height' of my test fixture to a minimum and out of the way of my LDRs resistor leads. Just a sec and I will show you guys
Thinking about our needs further for the LDRs and pairing it down to it's simplest realisation, all we need is a readout for each LDR that we can adjust & set.
This readout or dial would be on the front of the preamp & there would be one for each channel. We would adjust it once-off by having attaching a DMM to each channel's LDR and we would adjust the VCCS until both channels resistance was the same - then we set the front dial to the same number (dB or whatever). We do this for enough points in the useable volume range that we want and voila.
So now we know that the dials on the front panel when at the same number (dB?) mean both channel LDRs have the same resistance.
Now that I've written all this I see that what I'm actually talking about is a resistance readout on the front panel for each channels LDR and separate mono mode vol control
This readout or dial would be on the front of the preamp & there would be one for each channel. We would adjust it once-off by having attaching a DMM to each channel's LDR and we would adjust the VCCS until both channels resistance was the same - then we set the front dial to the same number (dB or whatever). We do this for enough points in the useable volume range that we want and voila.
So now we know that the dials on the front panel when at the same number (dB?) mean both channel LDRs have the same resistance.
Now that I've written all this I see that what I'm actually talking about is a resistance readout on the front panel for each channels LDR and separate mono mode vol control
Programmable, precision voltage to current converter -- from Texas Instruments (about 5 or 6 years ago) -- it was designed for nano-Amps but is shown here scaled for milliamps -- the INA121P will do a bit more than 10 mA -- but for an LDR
I searched for a precision current source for a transistor curve tracer I worked on several years back...helps if you have a drawer full of diff-amps.
Here's how the Vactrol relates to temperature:
And THD+N% at loads of 100K, 600R and 300R:
An externally hosted image should be here but it was not working when we last tested it.
I searched for a precision current source for a transistor curve tracer I worked on several years back...helps if you have a drawer full of diff-amps.
Here's how the Vactrol relates to temperature:
An externally hosted image should be here but it was not working when we last tested it.
And THD+N% at loads of 100K, 600R and 300R:
An externally hosted image should be here but it was not working when we last tested it.
Hi JKeny
The DS3901 will be of no utility if used without a master device.
Once programmed, you have only access to two settings per inbuilt resistor, full range can't be selected with a push button.
Those kind of chips are usualy programmed at factory and used in place of a trimmer.
Cheers
Francis
The DS3901 will be of no utility if used without a master device.
Once programmed, you have only access to two settings per inbuilt resistor, full range can't be selected with a push button.
Those kind of chips are usualy programmed at factory and used in place of a trimmer.
Cheers
Francis
Lightspeed remote control
Hi Folks,
I am not offended by inquiring minds. Without this we would never learn. Also I don't have the time to research every possible option available to provide a specific function. In fact I am being educated by some of the posts on the forum thread. I may never try the various options put forward, as I am happy with the performance of the VCCS for my application, but it is interesting to see what you come up with.
Keep posting your ideas for the benefit of all.
Regards
Paul
Hi Folks,
I am not offended by inquiring minds. Without this we would never learn. Also I don't have the time to research every possible option available to provide a specific function. In fact I am being educated by some of the posts on the forum thread. I may never try the various options put forward, as I am happy with the performance of the VCCS for my application, but it is interesting to see what you come up with.
Keep posting your ideas for the benefit of all.
Regards
Paul