Well, we are attempting to make things perfect now aren't we? If so then we need to look at everything.
If you are referring to the audio signal side Yes, one of charming features of audio purpose LDR's they are on their signal side a simple a variable resistor. that is then arranged as a conventional L pad.
However the anode and cathode side, to cause more or less light intensity to make that variance, is a different story altogether.
Your varying the intensity of an LED. How complicated is that? The intensity is changed by the pot.
Explanation of LED wiring per the internet
The LED's cathode is connected to the negative terminal of the battery. Connect the positive terminal of your battery supply to the left lead of a 1,000 ohm resistor. Connect the right lead of the resistor to the left lead of the LED. Connect the right lead of the LED to the negative terminal of the power supply.
Explanation of LED wiring per the internet
The LED's cathode is connected to the negative terminal of the battery. Connect the positive terminal of your battery supply to the left lead of a 1,000 ohm resistor. Connect the right lead of the resistor to the left lead of the LED. Connect the right lead of the LED to the negative terminal of the power supply.
Varying the intensity is not too complicated. The location of the pot to achieve change in volume is instead in the cathodes - The anode to cathode relationship has the anode /cathode of the LDR at a potential difference sufficient to achieve ideal attenuation as a volume control.
Signal side resistance is 62 ohms fully on, which is very close to the manufacturers specification of 60 ohms for a NSL32SR3
This is achieved with just 11ma of current total,with current consumption in the quiet listening range just 1.6ma and just 0.73ma at half volume.
http://lunainc.com/wp-content/uploads/2016/06/NSL-32SR3.pdf
The cathode is in this circuit some 9v above DC ground, vastly distant from signal ground, so quite different to the above explanation of an LED that has the cathode directly grounding being fed by a current source. Rather
the circuit can be described as a current source and current sink with the anode and cathode between the two.
Signal side resistance is 62 ohms fully on, which is very close to the manufacturers specification of 60 ohms for a NSL32SR3
This is achieved with just 11ma of current total,with current consumption in the quiet listening range just 1.6ma and just 0.73ma at half volume.
http://lunainc.com/wp-content/uploads/2016/06/NSL-32SR3.pdf
The cathode is in this circuit some 9v above DC ground, vastly distant from signal ground, so quite different to the above explanation of an LED that has the cathode directly grounding being fed by a current source. Rather
the circuit can be described as a current source and current sink with the anode and cathode between the two.
Sorry, I don't buy it.
Still has no effect on the audio portion of the circuit in my opinion. If an engineer wants to step in here I'm willing to listen. I've read a lot of stuff from people wanting to sell a product before. What I'm hearing about a supposed difference between the performance or your product such as increased bass as a result of this different "circuit" is very questionable. Its a simple circuit I'm not an engineer but I've done quite a bit in 40+ years however I'm not ready to consider this circuit any different than several others out there.
Still has no effect on the audio portion of the circuit in my opinion. If an engineer wants to step in here I'm willing to listen. I've read a lot of stuff from people wanting to sell a product before. What I'm hearing about a supposed difference between the performance or your product such as increased bass as a result of this different "circuit" is very questionable. Its a simple circuit I'm not an engineer but I've done quite a bit in 40+ years however I'm not ready to consider this circuit any different than several others out there.
Last edited:
This is where it gets interesting with LDR's . You need to hear what they do.
Stereo Coffee preamp compared to Lightspeed Attenuator
Stereo Coffee preamp compared to Lightspeed Attenuator
But have you heard one LDR vs another vs other passives ? as I think it would be a pity to resign your interest without even hearing them.
I wish it was a simple circuit but its plainly not a simple circuit, is the basic answer. With over 40 active components 6 resistors, and three capacitors each have been carefully tailored to do what they do with many carefully chosen component choices, all related to audio result.
On occasion I have de constructed sections to see if can be done more simply and every time it guides me back to the same or very similar layout.
As for an engineer stepping in, I designed the circuit. Can you honestly think of anyone better to be discussing this with ?
It looks like George Hifi was first to use a pair of LDR's as a voltage splitter/ volume control. Others have copied the idea with their little tweeks.
I can remember seeing optocouplers in both Electro voice and Altec Lansing products in one model of mixer that I can remember from the early 90's.
you have an actual engineering degree? From where?
I can remember seeing optocouplers in both Electro voice and Altec Lansing products in one model of mixer that I can remember from the early 90's.
you have an actual engineering degree? From where?
When I first read this thread I took a piece of paper and drew up how I thought the circuit would have to work. Guess what? I was right and I'm no engineer. I also figured out without a problem that your little tweeks were a simple attempt to make someone think you had come up with something different. Which of course you haven't.
Son, you can draw up an extensive power supply with additional components extra filtering and such and you really haven't done a damn thing except over complicate things and add additional parts. The operation of the LDR is quite simple. The resistance changes with light I can prove that. The LED is separate from the resistance and I can prove that. Any thoughts as to the LED injecting any noise into the circuit that can be heard are pure horse hockey. The supposition that one design gives more bass or better sound stage is pure nonsense. Its called marketing hype. The circuit is simple the audio is routed thru a simple voltage divider and it acts like a pot with a wiper without actually having a wiper both sides of the divider change when you vary the intensity of the LED. Anything else is pure nonsense. The supply to the LED needs only not to fluctuate when the control isn't being turned.
Hell, maybe I should start selling a LDR control like this. I can throw in a couple of diodes in the power supply put it on a ground plane circuit board and claim it has a lower noise threshold. Count on my putting one of these together and when I'm done I'll take it to where I was employed for years and dig out some test gear and do some actual testing.
The stereo coffee circuit has always used a single gang potentiometer
and a op amp, it has never borrowed anything from the circuit George provided to DIY audio. I find such assertions quite insulting, with a circuit that has never had any resemblance, and never will.
The single gang pot being wrongly delivered to me in 2008, where i set about
designing to use only a single gang and every circuit since other than balanced boards, has used a single gang.
The op amp presently a LM833 dual, serves purpose to bias the bases of 2n5088 transistors from DC at each opamp output, being 1.4v
relative to the opamp negative rail, which itself is not grounded
A engineering degree is thankfully not necessary to be involved in audio design. It would just hold me up.
This is nothing more than another audio forum with a member or two saying they think brand B sounds better than brand A. There is absolutely no proof other than the I think this one sounds better.
The stereo coffee circuit has always used a single gang potentiometer
and a op amp, it has never borrowed anything from the circuit George provided to DIY audio. I find such assertions quite insulting, with a circuit that has never had any resemblance, and never will.
The single gang pot being wrongly delivered to me in 2008, where i set about
designing to use only a single gang and every circuit since other than balanced boards, has used a single gang.
The op amp presently a LM833 dual, serves purpose to bias the bases of 2n5088 transistors from DC at each opamp output, being 1.4v
relative to the opamp negative rail, which itself is not grounded
A engineering degree is thankfully not necessary to be involved in audio design. It would just hold me up.
If you had a degree this might be interesting. Like I said added parts that contribute nothing. Just a different way of playing with the LED lighting that adds absolutely nothing to the audio simply because you cannot change the audio.
- Status
- Not open for further replies.