Infra Red Remote Control LDR Volume Control.
I have been using LDR volume control for many years in the form of an L-pad with a series resistor and a shunt LDR without knowing anything of George Stantscheff’s Lightspeed volume control. This was the same configuration George used in his early products. George had a further idea of making the series element of the L-pad an LDR too and this improved the performance even further. A couple of years ago I came across a thread on DIY Audio that was devoted to George’s Lightspeed design and decided to try his latest configuration in my system. It was an immediate upgrade on the previous series resistor/shunt LDR design. As far as I am concerned it is without doubt the best method of volume control I have ever used with respect to sound quality.
Please note that Lightspeed is the name George has been using for his production volume controls and this should not be used for any of the LDR volume control clones that are now available. For those interested in George’s product he can be contacted at email@example.com
The Lightspeed volume control uses a standard dual potentiometer to adjust the current in the LDR LEDs thus varying the signal attenuation by controlling the LDR resistance. There is no remote control option on the Lightspeed. I am used to the convenience of remote control so decided to design one for myself using voltage controlled current sources interfaced with infra-red control modules. I mentioned this on Georges Lightspeed thread on DIY Audio and a lot of interest was shown. I decided that it would be a good DIY project to add to the thread and with George’s blessing offered a group buy to those who had shown interest. The circuit was published around a year and a half ago and a printed circuit board run was commissioned. I offered a set of boards for those with suitable DIY skills and also built and tested modules for those with less experience with a soldering iron. The boards and modules were priced to cover the provision costs with no additional business profit added.
The VCCS LDR current source drivers can be configured for single ended or balanced signal processing and provide Volume up/down and Channel Balance left/right. The VCCS can be controlled with four momentary switches fitted to your preamp front panel and/or used with the Infra Red Transmitter and Receiver modules to give the remote control function. The LDRs are not provided with the module. They should be purchased in matched sets from Uriah Daily at http://www.buildanamp.com/
Some technical information and photos :-
VCCS circuit http://i700.photobucket.com/albums/ww7/paulhynes/VCCS1C.jpg
IRT circuit http://i700.photobucket.com/albums/ww7/paulhynes/IRT1A.jpg
IRR circuit http://i700.photobucket.com/albums/ww7/paulhynes/IRR1A.jpg
VCCS photo http://i700.photobucket.com/albums/ww7/paulhynes/VCCS1A1.jpg
All modules photohttp://i700.photobucket.com/albums/ww7/paulhynes/LightspeedRemoteControl.jpg
VCCS with ultra low noise regulatorshttp://i700.photobucket.com/albums/ww7/paulhynes/Picture2019.jpg
LDR remote control reviewhttp://www.tnt-audio.com/accessories/ph_ldr_volume_control_e.html
There is still plenty of interest for the VCCS control system and because of this the boards and modules are still available for anyone wanting to set up a DIY infra-red remote controlled LDR volume control.
The prices are still the same as when they were introduced and are :-
VCCS (voltage controlled current source LED control)
Built module £60
IRT (transmitter module) and IRR (receiver module) sold as a matching pair
Built modules £49.60
Low noise regulators for the VCCS (2 x shunt and 1 series)
Built and tested modules only - £96 for the three.
Insured air carriage and packing will be charged at cost and is subject to destination. This can be quoted at the time of enquiry.
If you have any questions about application of the modules post them on this thread for discussion and this will also act as a knowledge source for others considering LDR volume control.