audioguru Posted March 3, 2006 Report Share Posted March 3, 2006 Can i use any average detector instead of the one in data sheet? I have some LM358. can i use them to build average detector for my LM3915? Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 4, 2006 Author Report Share Posted March 4, 2006 every ( inverted signal)circuit need dual supply? is this what do you mean? do you mean integrator Op-amp? hemm this mean i need another circuit for integrator? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 4, 2006 Report Share Posted March 4, 2006 Your circuit doesn't need a "perfect" integrator. just a capacitor charged and discharged by the same resistor, and a high resistance load for the capacitor will be fine for your circuit. Decrease the value of C8 for a quicker response time: Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 6, 2006 Author Report Share Posted March 6, 2006 Hello, i cannot figure out how the average detector work. It seem kind of half wave rectifier to me? well i'll try this out today.What value of the Rhi should I set? 2.5v? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 6, 2006 Report Share Posted March 6, 2006 The opamp that feeds the average detector is a half-wave rectifier because without signal its output is at 0V.The average detector has its rise and fall times the same and its response is slow so its output is the average of sounds picked up by the microphone.Peak sound levels must be allowed to be amplified normally without clipping so the average voltage will be much less. Perhaps a voltage of 1.6V should be used for Rhi to allow the peaks to be 10dB (3.16 times) higher than the average voltage. Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 7, 2006 Author Report Share Posted March 7, 2006 Hello, The circuit work very well using the Average detector. figure bellow show how i supply my Rhi. When i change the R1 to smaller value (20k), the first 2 LED will lights. When i use 220k, the first 5th LED wont light up (dot mode). It starting on the 6th LED. Playing with the R1 value can give me a good result without knowing what is the true Voltage or current for the Rhi. Any comment about the diagram above? how i can supply my Rhi with 1.6v? btw, the capacitor seem does not affect The Rhi? am i right? How do i make the LED to discharged slowlly? i meant, the LED suppose to light up quickly(sensitive) but light off slowlly? increase the C8 value will do the job? Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 7, 2006 Author Report Share Posted March 7, 2006 Hello Again. I come up with a new question. I'm planing to connect the 14th or13th (or 12th) LED to trigger the interrupt on my PIC16F84. I think that we can generate needed voltage for interrupt by connecting the signal form an LED to an logic gate. Here i use an AND Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 7, 2006 Report Share Posted March 7, 2006 The circuit work very well using the Average detector.Good. When i change the R1 to smaller value (20k), the first 2 LED will lights. When i use 220k, the first 5th LED wont light up (dot mode). It starting on the 6th LED. Playing with the R1 value can give me a good result without knowing what is the true Voltage or current for the Rhi.The datasheet says that the resistance at Rhi is typically 28k. You can measure the voltage of Rhi or calculate it. With a 5V reference and 20k in series with the 28k, the Rhi voltage is 2.92V. Using 220k, the Rhi voltage is 0.57V. how i can supply my Rhi with 1.6v?The voltage reference pin of the LM3915 Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 8, 2006 Author Report Share Posted March 8, 2006 CMOS Logic is new to me. I haven't have any experiance with it. Now i'm reading about it. okey. now the question arise, which Cmos logic to use? i never uses any before. What is the model number? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 8, 2006 Report Share Posted March 8, 2006 Why use a logic gate? It wasn't gating anything. Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 8, 2006 Author Report Share Posted March 8, 2006 how about comparator? we can use comparator to compare 2 current right? comparator such as LM393 has a very low bias current.http://www.onsemi.com/pub/Collateral/LM393-D.PDFif logic not possible,do you have any suggestion? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 8, 2006 Report Share Posted March 8, 2006 You need to detect when an LED blinks, since your LM3915 is in the DOT mode.A logic gate or a comparator isn't needed. The LED to be detected operates with current, not voltage.The LED of an optical-coupler could be connected in series with the LED to be detected and its phototransistor could drive the interrupt of the microcontroller, if the LED "blink" duration is long enough. A monostable might be needed to extend the duration of the "blink". Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 8, 2006 Author Report Share Posted March 8, 2006 how if i operate the LM3915 in bar mode? is there is any method else then you have mention above? Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 8, 2006 Report Share Posted March 8, 2006 In the BAR mode, an LED will remain lighted when the sound level is reached and is exceeded. The current in the detected LED can still be detected with an optical isolator.The battery won't last very long when many LEDs light in the BAR mode. Quote Link to comment Share on other sites More sharing options...
ryeeson Posted March 16, 2006 Author Report Share Posted March 16, 2006 i have this idea. Can i connect the signal to a ADC converter? let say i connect it to a PIC's ADC pin. we run the program to check the level of the converted signal. Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 16, 2006 Report Share Posted March 16, 2006 i have this idea. Can i connect the signal to a ADC converter? let say i connect it to a PIC's ADC pin. we run the program to check the level of the converted signal.Sure, your picis fast enough to check the level of an average-detected and rectified signal. Quote Link to comment Share on other sites More sharing options...
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