I am sure many of you have tried this, but if you have the inclination and the opportunity you might put some small electrolytics in your circuit. Snub the LDRs with them. The sound quality goes up. I used 100uf. Some guys used 47uf and some only 10uf. Probably all values are overkill but just try it.
Seems the sound is more smooth.
Uriah
Seems the sound is more smooth.
Uriah
Udailey and Maximus-
Thanks for this. Maximus, would your VCCS schematic benefit from this? I would gather not as the IC2 is a buffer/driver?
Maximus- I find I need to click the volume button up quite a bit before I get sound; I gather I have too much resistance in R1-R4? Or am I getting it backwards?
Great circuit, BTW! Prob the last volume control I will ever use.
-Kent
Thanks for this. Maximus, would your VCCS schematic benefit from this? I would gather not as the IC2 is a buffer/driver?
Maximus- I find I need to click the volume button up quite a bit before I get sound; I gather I have too much resistance in R1-R4? Or am I getting it backwards?
Great circuit, BTW! Prob the last volume control I will ever use.
-Kent
May I see pictures of the wiring? I have 2 assembled and waiting for enclosures but have been hesitant.
Hi Kent,
I haven’t tried a cap bypass on the LDR LED so I can’t advise you from experience with this. In theory the LF347 op amps are unity gain stable so it may be possible without causing instability.
If you are using 39k resistors for R1-R4 you could reduce the resistor values to bring the volume up earlier. You will have to experiment with the resistor values to suit your system.
Hi Troy,
Sorry I have no pictures of the VCCS wired and I have changed the set-up in my system to include source selection switching with LDRs so my set-up is no longer the standard VCCS application. I think there have been several posts by constructors showing pictures of their wiring so have a look back through the thread. Quite a number of board sets/modules have gone out so maybe someone can post pictures of their wiring.
Regards
Paul
I haven’t tried a cap bypass on the LDR LED so I can’t advise you from experience with this. In theory the LF347 op amps are unity gain stable so it may be possible without causing instability.
If you are using 39k resistors for R1-R4 you could reduce the resistor values to bring the volume up earlier. You will have to experiment with the resistor values to suit your system.
Hi Troy,
Sorry I have no pictures of the VCCS wired and I have changed the set-up in my system to include source selection switching with LDRs so my set-up is no longer the standard VCCS application. I think there have been several posts by constructors showing pictures of their wiring so have a look back through the thread. Quite a number of board sets/modules have gone out so maybe someone can post pictures of their wiring.
Regards
Paul
Maybe but sadly none have posted a picture thus far. (of the VCCS modules assembled and installed)
Hi Troy,
Leo also posted some excellent pictures on post 2284 page 229. Between these and Kents photos you should be able to see what is connected where. Circuits and board layouts were posted on post 2738 page 274. If you are still unsure after looking at these get back to me with details of the sections you are not sure about and I will see if I can help.
Regards
Paul
Leo also posted some excellent pictures on post 2284 page 229. Between these and Kents photos you should be able to see what is connected where. Circuits and board layouts were posted on post 2738 page 274. If you are still unsure after looking at these get back to me with details of the sections you are not sure about and I will see if I can help.
Regards
Paul
kstlfido- Thank you for the reply and picture but I was looking for more of the finished install. Reasons to follow....
Paul- Leo's does look great and I will certainly use it as a reference but I was waiting for a complete example that included front panel controls. But his (and kstlfido's) DOES clear up the remote recievers wiring issue. I was thinking it required computer "type" ribbon cable to tie the PCB's together.
I will make a commitment to finish these controllers this calendar year.. 🙂
So I will have to source acceptable front panel switches.
A WAF grade remote (for Mr. G, I can use whatever).
and then go back and figure out what the requirement on the switch voltage / not to touch ground issue was.
Paul- Leo's does look great and I will certainly use it as a reference but I was waiting for a complete example that included front panel controls. But his (and kstlfido's) DOES clear up the remote recievers wiring issue. I was thinking it required computer "type" ribbon cable to tie the PCB's together.
I will make a commitment to finish these controllers this calendar year.. 🙂
So I will have to source acceptable front panel switches.
A WAF grade remote (for Mr. G, I can use whatever).
and then go back and figure out what the requirement on the switch voltage / not to touch ground issue was.
Uriah,
I have been reading up on snubbber circuits and am unsure where the cap would go, in series or parallel to the ldr? I have found on the S&B tranny website they put a snubber cap in series if needed.Other than that I couldn't find much info.
Stevens & Billington Limited Audio transformers TX-102
Thanks for asking that triode4, I was wondering myself but have been too reticent to ask 😱.
Uriah, how about a little sketch for us beginners ?.
Thanks...
I would imagine parallel; if cap wired in series it would block DC to the LED!! 🙂
I'm not sure where S&B put the cap, but I gather a cap would be there to block DC from entering the TVA. Otherwise the core *could* saturate.
Or I could be wrong!
I'm not sure where S&B put the cap, but I gather a cap would be there to block DC from entering the TVA. Otherwise the core *could* saturate.
Or I could be wrong!
The LDR cap
The cap is there to reduce noise, etc on the LED and has no connection at all to the Variable Resistor.
The way used to describe this device has always been confusing - the Light Emitting Diodes (leds) shine variable amounts of lumens (light) onto the Light Dependent Resistor (ldr) so offering the electrical isolation .....
It's really a "light controlled variable resistor" and should be known as a LCVR, IMO!
The effect you get with adding a cap across the LED pins will vary with different types of circuits that control the LED current (or voltage) - sometimes no change at all, as George found in the original "basic" cct - sometimes not apparent in some systems - so simple to try it for yourself.
... 2cents
The cap is there to reduce noise, etc on the LED and has no connection at all to the Variable Resistor.
The way used to describe this device has always been confusing - the Light Emitting Diodes (leds) shine variable amounts of lumens (light) onto the Light Dependent Resistor (ldr) so offering the electrical isolation .....
It's really a "light controlled variable resistor" and should be known as a LCVR, IMO!
The effect you get with adding a cap across the LED pins will vary with different types of circuits that control the LED current (or voltage) - sometimes no change at all, as George found in the original "basic" cct - sometimes not apparent in some systems - so simple to try it for yourself.
... 2cents
Hi Troy,
This is also for any others struggling to understand the application of the VCCS module and the Infra Red Remote modules with regard to control function.
I haven’t fitted front panel switches to my unit so I can’t provide you with a photo. Instead I will try to explain the circuit operation for you in a way you can understand.
If you look at the circuit diagram for the VCCS module it shows the switch arrangement. The switches are floating above actual ground along with the DS1802, as they have to be referenced to the DS1802 pin 14 to work. If you look at the DS1802 data sheet pin diagram you will notice that pin 14 is designated AGND (analogue ground). The DS1802 has to be floated 3.3 volts above ground to fit within the common mode input range of the LF347 voltage controlled current source. This means that pin 14 on the DS1802 now sits at 3.3 volts above ground. Pin 14 is still the DS1802 chip reference point for all functional pins 16 to 19. Pin 15 is not used in this application.
Pins 16 to 19 are normally pulled high to pin 20 potential internally in the chip. To instruct the chip potentiometers what to do, the relevant instruction pin should be shorted with a momentary action switch to pin 14 even though this pin is not referenced to actual ground in this application. In fact connection of pins 16 to 19 to actual ground could damage the DS1802, as this would place the terminals outside their voltage operating range.
Referring back to the VCCS switch drawing and looking at the VCCS board layout you will notice that connector pins 1-6 are duplicated using a double row of connectors. This duplication allows both the Infra Red Receiver (IRR) board and the front panel momentary push button switches to be connected to the module at the same time. It does not matter whether you use the remote control or the front panel switches to instruct the DS1802, as either option will reference the control pins 16-19 to pin 14. The VCCS circuit diagram switch section shows which of connector pins 1-5 are connected to pins 14, and 16 to 19 on the DS1802 and the function of the pins referred to in the DS1802 data sheet. Pin 6 of the connector is only used to provide power to the IR Receiver board, which is also floating above actual ground along with the DS1802, and it is not involved in any switching actions.
You can use any insulated wire type you wish for the control functions, just make sure you get the pins matched correctly on the VCCS and the IR Receiver board and the front panel momentary switches match the required function pin of the DS1802.
I hope this clears any confusion regarding the connection of the control pins. I understand that some of you may be relatively new to DIY electronics and the operation of the VCCS module may not be easily understood. If my description above is still not clear do say so and I will try to explain in a way you understand. It would help if you can highlight any particular point that is not clear.
Regards
Paul
This is also for any others struggling to understand the application of the VCCS module and the Infra Red Remote modules with regard to control function.
I haven’t fitted front panel switches to my unit so I can’t provide you with a photo. Instead I will try to explain the circuit operation for you in a way you can understand.
If you look at the circuit diagram for the VCCS module it shows the switch arrangement. The switches are floating above actual ground along with the DS1802, as they have to be referenced to the DS1802 pin 14 to work. If you look at the DS1802 data sheet pin diagram you will notice that pin 14 is designated AGND (analogue ground). The DS1802 has to be floated 3.3 volts above ground to fit within the common mode input range of the LF347 voltage controlled current source. This means that pin 14 on the DS1802 now sits at 3.3 volts above ground. Pin 14 is still the DS1802 chip reference point for all functional pins 16 to 19. Pin 15 is not used in this application.
Pins 16 to 19 are normally pulled high to pin 20 potential internally in the chip. To instruct the chip potentiometers what to do, the relevant instruction pin should be shorted with a momentary action switch to pin 14 even though this pin is not referenced to actual ground in this application. In fact connection of pins 16 to 19 to actual ground could damage the DS1802, as this would place the terminals outside their voltage operating range.
Referring back to the VCCS switch drawing and looking at the VCCS board layout you will notice that connector pins 1-6 are duplicated using a double row of connectors. This duplication allows both the Infra Red Receiver (IRR) board and the front panel momentary push button switches to be connected to the module at the same time. It does not matter whether you use the remote control or the front panel switches to instruct the DS1802, as either option will reference the control pins 16-19 to pin 14. The VCCS circuit diagram switch section shows which of connector pins 1-5 are connected to pins 14, and 16 to 19 on the DS1802 and the function of the pins referred to in the DS1802 data sheet. Pin 6 of the connector is only used to provide power to the IR Receiver board, which is also floating above actual ground along with the DS1802, and it is not involved in any switching actions.
You can use any insulated wire type you wish for the control functions, just make sure you get the pins matched correctly on the VCCS and the IR Receiver board and the front panel momentary switches match the required function pin of the DS1802.
I hope this clears any confusion regarding the connection of the control pins. I understand that some of you may be relatively new to DIY electronics and the operation of the VCCS module may not be easily understood. If my description above is still not clear do say so and I will try to explain in a way you understand. It would help if you can highlight any particular point that is not clear.
Regards
Paul
Here my value:
SERIES LDR
RX
MIN 7.30...7.57 kohm
MAX 57.8 ohm
SX
MIN 6.4..6.5 Kohm
MAX 55.1 ohm
SHUNT LDR
SX
MIN 49 ohm
MAX 2590 ohm
DX
MIN 156 ohm
MAX 725 ohm
Measured at 5volt, no audio signal
First, yes the cap is across, parallel with, the LED. Noise from the power supply comes across the LED and injects into the resistor side of the LDR.
Arnold,
Man DX is messed up. Can I see your set up? Odd that your system should be getting loud fast with these readings, but maybe that messed up DX is going from low to max instantly.
Either way, DX is broken or you have something wired wrong to it. Pics?
Uriah
Arnold,
Man DX is messed up. Can I see your set up? Odd that your system should be getting loud fast with these readings, but maybe that messed up DX is going from low to max instantly.
Either way, DX is broken or you have something wired wrong to it. Pics?
Uriah
Uriah -
1 - the link to google docs in post 3458 seems to be broken.
2 - with regard to the snubbers: should they go on all 4 LDRs or just the series??
This thread is always interesting.
Thanks,
1 - the link to google docs in post 3458 seems to be broken.
2 - with regard to the snubbers: should they go on all 4 LDRs or just the series??
This thread is always interesting.
Thanks,
Ray,
I posted another a few pages back. That one works fine.
Snubbers. Interesting. I use them on the 4 but who know? Maybe series only would be fine. Either way its a 40 cent investment. I highly doubt audiophile caps are needed here and also dont use big caps, just 100uf or less.
This one is fine https://docs.google.com/fileview?id...DUtZTkyOS00YjU2LTk1ZDEtZjZiYjg1OTNjMzdm&hl=en
Uriah
I posted another a few pages back. That one works fine.
Snubbers. Interesting. I use them on the 4 but who know? Maybe series only would be fine. Either way its a 40 cent investment. I highly doubt audiophile caps are needed here and also dont use big caps, just 100uf or less.
This one is fine https://docs.google.com/fileview?id...DUtZTkyOS00YjU2LTk1ZDEtZjZiYjg1OTNjMzdm&hl=en
Uriah
Hi Paul, where can one find out more about the VCCS modules and boards and prices?
thanks!
The pot
I have tested a number of potentiometers in my Lightspeed attenuator. The result shows that the sound varies greatly from one pot to another.
The tested pots are the cheap carbon film, ALPS blue case, Sfernice ceramic, TKD 2CP601 conductive plastic, and so on. What I found is that the more expensive the pot, the better the sound. The TKD is much better than the ALPS or so in every aspect.
In my humble opinion, the pot still plays the major role even in the LDR scheme.
I have tested a number of potentiometers in my Lightspeed attenuator. The result shows that the sound varies greatly from one pot to another.
The tested pots are the cheap carbon film, ALPS blue case, Sfernice ceramic, TKD 2CP601 conductive plastic, and so on. What I found is that the more expensive the pot, the better the sound. The TKD is much better than the ALPS or so in every aspect.
In my humble opinion, the pot still plays the major role even in the LDR scheme.
