Neat idea. I have some of these devices so I breadboarded two in series. Enough current through the LEDs (also in series) to make the total resistance 5K more or less. Tap to ground just about 2.5K as expected. Applied 2 volts signal to the pot and measured distortion at the tap. 0.06% distortion at 1 KHz. It is largely third harmonic. This is about ten times the distortion through my home built system from CD all the way through to speaker terminals!
The BDX53C transistor at power supply section heats up, case worst in split supply whereby it gets heated up tremendously even thru I put up heatsink. CHecked the circuit, all connection properly soldered. Can any one check and share the experience? Thanks
Shunt supply will put all the current through the BDX53, if there is no load connected (that's the worst case for shunt regulator if we're talking about heating). If there is a load, part of the current will flow through it, and part through BDX53.
23rd October 2010, 07:00 AM
The Poor Serbian Man's Optical Attenuator
Manu
Great article ...
And a real pleasure to read
Sincerely admirative
Manu