Lightspeed remote control
Hi Vernon,
Under normal operation the mute button clamps the wiper at the low end of the pot track. There may also be an additional clamp across the signal line as the mute level is noticably lower than the minimum volume level spec. Anyway actuating the mute button will not mute the lightspeed, it will just set the lightspeed at minimum volume.
If you can do without the balance control function and use matched LDRs you would have a couple of buttons left for alternative functions like actuating the mute pin (track surgery required).
If you decide to design in a function that is external to the VCCS do remember that the IR receiver module power supply comes from the 5 volt shunt regulator that powers the DS1802 and this floats 3v3 above earth. You will have functional problems if you try to reference the IR receiver to earth without some form of opto-isolator to transfer the signal to an alternative system function that is ground referenced.
Regards
Paul
Hi Vernon,
Under normal operation the mute button clamps the wiper at the low end of the pot track. There may also be an additional clamp across the signal line as the mute level is noticably lower than the minimum volume level spec. Anyway actuating the mute button will not mute the lightspeed, it will just set the lightspeed at minimum volume.
If you can do without the balance control function and use matched LDRs you would have a couple of buttons left for alternative functions like actuating the mute pin (track surgery required).
If you decide to design in a function that is external to the VCCS do remember that the IR receiver module power supply comes from the 5 volt shunt regulator that powers the DS1802 and this floats 3v3 above earth. You will have functional problems if you try to reference the IR receiver to earth without some form of opto-isolator to transfer the signal to an alternative system function that is ground referenced.
Regards
Paul
I have decided to stay with the simple passive LDR so beautifully prepared fore us by Uriah (and George)
I will probably have a couple around the house
One dedicated fore a small "pure sonics" tubeamp setup, I hope to do in near future
The complex VCCS version, was intended fore a big 3way with horn/waveguide top
As it will need active crossover anyway, such effort would probably be completely wasted
Very different set of priorities to make such big design work
Sorry to waste your time on that issue
Simple is beautiful
I will probably have a couple around the house
One dedicated fore a small "pure sonics" tubeamp setup, I hope to do in near future
The complex VCCS version, was intended fore a big 3way with horn/waveguide top
As it will need active crossover anyway, such effort would probably be completely wasted
Very different set of priorities to make such big design work
Sorry to waste your time on that issue
Simple is beautiful
jkeny said:
I have not built this multi input version that someone posted, but I believe at a quick glance it's so the output of the source (cd player) doesn't get shorted directly to ground and blow it up when the relay mutes that input to ground, as it still has the first ldr unpowered (1megohm resiatance approx) between the sources output and the earth shorted relay.
Cheers George
BSP149
Salut
I'm having trouble sourcing the BSP149 here in France for Paul's VCCS. We have Farnel but they don't deal with the public. Is there an equivalent (google didn't help) or can someone help, please? I need at least two - three would be better as I'm sure to fry one.
Merci.
Vernon
Salut
I'm having trouble sourcing the BSP149 here in France for Paul's VCCS. We have Farnel but they don't deal with the public. Is there an equivalent (google didn't help) or can someone help, please? I need at least two - three would be better as I'm sure to fry one.
Merci.
Vernon
Does anybody else have trouble getting the right 32SR2 optocouplers from Farnell? By now I've tested 50 of them and at 1ma they are anything from 1k-7k ohms which is way too much. Stamp is 109. Out of the 50 only 3 are between 110-220 ohms@1ma.
I told Farnell the batch has a production fault and I would lilke another batch but they keep sending me new ones from the same batch.
Luckily I have another 25 with the most having a stamp 085 which measures notably better.
Made a new PCB with a constant voltage output so I can test 10 in 1 go because any small temp/volt fluctuation alters the outcome too much and makes it difficult to find proper pairs.
these are the ones sofar with the best specs:
0,01 ma 12-30k
0,1ma 800-1k2
0,5ma 260-310 ohms
1ma 115-220 ohms
25ma 23-30 ohms
Proper pair found:
25k-27k
1064-1072 ohms
294-295 ohms
161-162 ohms
28-29 ohms
Are these values OK to you?
Bert
I told Farnell the batch has a production fault and I would lilke another batch but they keep sending me new ones from the same batch.
Luckily I have another 25 with the most having a stamp 085 which measures notably better.
Made a new PCB with a constant voltage output so I can test 10 in 1 go because any small temp/volt fluctuation alters the outcome too much and makes it difficult to find proper pairs.
these are the ones sofar with the best specs:
0,01 ma 12-30k
0,1ma 800-1k2
0,5ma 260-310 ohms
1ma 115-220 ohms
25ma 23-30 ohms
Proper pair found:
25k-27k
1064-1072 ohms
294-295 ohms
161-162 ohms
28-29 ohms
Are these values OK to you?
Bert
Last time I tested I had LDRs from 3 different batches. You will have the best matching within one single batch. To have all 109 is a good thing.
Please show a picture of your test setup. You have 50 LDRs this should be easy to get a match from.
I dont know how your test setup is but I take 5V and feed that to at least 12 and usually 24 different trimpot. All trimpots are trimmed to exact same resistance. Then LDR in series with trimpot and then to shared ground or 0V.
Then wait 15min in still room no air moving. Come in and test while they are still powered up.
I dont care at all about mA although it all translates. But you know with 5V in series with 40k I can get anything from 300r to 22kOhms. Thats extremes over 300 or so LDRs but you should usually with 40k and exactly 5V get a bunch of them grouping somewhere between 2k and 5k.
So, how are you doing it and what resistors are you using.
I am off to the zoo and will read your reply tonight.
Uriah
Please show a picture of your test setup. You have 50 LDRs this should be easy to get a match from.
I dont know how your test setup is but I take 5V and feed that to at least 12 and usually 24 different trimpot. All trimpots are trimmed to exact same resistance. Then LDR in series with trimpot and then to shared ground or 0V.
Then wait 15min in still room no air moving. Come in and test while they are still powered up.
I dont care at all about mA although it all translates. But you know with 5V in series with 40k I can get anything from 300r to 22kOhms. Thats extremes over 300 or so LDRs but you should usually with 40k and exactly 5V get a bunch of them grouping somewhere between 2k and 5k.
So, how are you doing it and what resistors are you using.
I am off to the zoo and will read your reply tonight.
Uriah
I wouldn't be too worried about the variation at that extreme. That was with .01ma, which would require a 300K ohm resistor in series (assuming 5v supply with a 2v LED dropout), or a 150K with two LEDs in parallell. That's about the full range of the pots most people are using, and the resistance of the other LDR would probably be so low (1000:1 ratio) that it wouldn't matter.
what I use now to test it with is a LM317 with a resistor att. circuit fed into a selector and feeding the optocouplers in parallel, although each has a 100ohm resistor in series to measure the current, and measuring the output LDR resistance on a fluke multimeter.
At 10uA the 25-27k difference is small.
It is within 1%
I find that the only way to do an exact measurement is to use as many LDR's as possible in 1 go.
There just are too many variable elements otherwise.
I will post a circuit diagramm of the test circuit used tomorrow.
Its nearly 1 o'clock at night now. So I have to go to sleep
At 10uA the 25-27k difference is small.
It is within 1%
I find that the only way to do an exact measurement is to use as many LDR's as possible in 1 go.
There just are too many variable elements otherwise.
I will post a circuit diagramm of the test circuit used tomorrow.
Its nearly 1 o'clock at night now. So I have to go to sleep
Bgt said:
Very true. This is the most important part. If for instance you decide you are going to measure them with 1k in series then do ALL your LDRs at that time for that single measurement. Set aside a great deal of time for each measurement. Coming back tomorrow to do the same one will result in bad matching.
Uriah
As I promised
http://www.grotel.nl/photo/LScontroller.jpg
just testing the level controller now with a scope to see if channel symetry is ok. It looks ok anyway so time to build it in a preamp.
http://www.grotel.nl/photo/LScontroller.jpg
just testing the level controller now with a scope to see if channel symetry is ok. It looks ok anyway so time to build it in a preamp.
working unit
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
