Re: converting line-level audio signal to resistance?

Question

Then I wrote:---Zero ohms is tough, but here's a start:                      +---[R]--+        +---->OUT                      |        |        |                      |      [LED]--> [LDR]AUDIO>---[C]----+-----+--|-   |        |                |        |  >--+        +---->OUT               [R]    +--|+/                |     |GND>------------+     |                |     |              [POT]------------+Maybe there's a better way.  What's your application?-- John FieldsProfessional Circuit Designer ---Then he wrote:---Then I wrote and crossposted to sed:Not really.  Just view it using a fixed pitch font like Courier andif it still doesn't make sense post back with what you don'tunderstand.-- John FieldsProfessional Circuit Designer

Mad Scientist Jr · Accepted Answer

AUDIO> is positive or ground or both?[C} is capacitor? how much?[R] is resistor? how much?what is [LDR] ? is this a light sensor ?[LDR] has 2 outputs, do these go to the +5v and gnd of the paddle?What is the [POT] between Gnd and Vcc? Is this to adjust the gain ofthe audio driving the LED?What is Vcc?thanksNot really.  Just view it using a fixed pitch font like Courier andif it still doesn't make sense post back with what you don'tunderstand.                      +---[R]--+        +---->OUT                      |        |        |                      |      [LED]--> [LDR]AUDIO>---[C]----+-----+--|-   |        |                |        |  >--+        +---->OUT               [R]    +--|+/                |     |GND>------------+     |                |     |              [POT]------------+ -- John Fields Professional Circuit Designer

John Fields · Answer

Then I wrote:---Zero ohms is tough, but here's a start:                      +---[R]--+        +---->OUT                      |        |        |                      |      [LED]--> [LDR]AUDIO>---[C]----+-----+--|-   |        |                |        |  >--+        +---->OUT               [R]    +--|+/                |     |GND>------------+     |                |     |              [POT]------------+Maybe there's a better way.  What's your application?-- John FieldsProfessional Circuit Designer ---Then he wrote:---Then I wrote and crossposted to sed:Not really.  Just view it using a fixed pitch font like Courier andif it still doesn't make sense post back with what you don'tunderstand.-- John FieldsProfessional Circuit Designer

John Fields · Answer

---AC referenced to ground (GND)------1000µF. Maybe 16 V?------620 ohms------Light-Dependent-Resistor/Photocell------You asked for a resistance which varied as a function of some audioinput, not for a pot, and that's what you've got.  If you want a potyou'll need to build two circuits with the photocells wired inseries and the LEDs illuminating them out of phase.  Like this:              Vcc       |         |    [LED1]--> [LDR1]       |         |               +----->     |         |   [LED1]--> [LDR2]     |         |              GNDOr, since it appears what you _really_ want is a voltage whichvaries between 0 and 5V depending on what?  How loud your stereo'splaying?  Too bad you didn't say that's what you wanted in the firstplace, since that's easy to do.--- ---No, it's to set the zero sinal operating point of the LED-LDR pair--- ---The supply voltage. 5VDC.---Just for grins you might want to go to:Download their simulator, copy the following file as ASCII text,name it  and run...

Re: converting line-level audio signal to resistance?

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