In previous post I created circuit that could show audio spectrum on one 10 segment led bargraph display. Also in previous post I encountered problem with signal strength, so I have to implement solution on adjusting audio signal level.
But before creating amplifier, I decided that I should stack up another led bargraph, so i would have 20 led segments in a row.
This way I will have bigger range to test audio amplifier performance.
The fundamentals of getting it done is wiring two LM3914 IC so that they would work "hand-in-hand". I.e. when signal is 0, both LED bargraphs should be blank (not lit), when signal is to the max, both LED bargraphs should be lit fully.
While searching through the Internet, I saw different versions of combining these IC, but believe it or not, the best diagram can be found in official LM3914 datasheet. :)
I recreated the diagram so it would be a bit more understandable taking out mode switch and rearranging LM3914 IC placement in original scheme.
This is what I got:
Using this scheme, I created circuit on a breadboard:
Don't pay attention to the resistor across the led bargraph. I rearranged it afterwards.
And this is the video of what I got:
As you can see, signal from computer is only strong enough to light only one LED bar graph. So next step will be signal amplifier implementation.
At this point I was wondering, is the second bar graph actually working or is there a problem in my circuit. But when I disconnect audio jack, both led bargraphs light up. This is a good sign as I can see, that both ledbars are working. But, I will have to find out, why is it lighting up when I disconnect signal and how to prevent it.
Problems:
1. Implement pot to adjust LED brightness.
2. Implement audio signal amplifier.
3. Find out why both led bargraphs are lit when audio jack connector is disconnected and how to prevent it.
4. I should order few LM3916 ICs and try them instead of LM3914 as they are more suitable for audio signal metering.
4. I should order few LM3916 ICs and try them instead of LM3914 as they are more suitable for audio signal metering.
a nav tā, ka tev vnk jāpazemina kkas tur? spriegums/strāva?
AtbildētDzēstjoa.. tev tas ledbars pie klusuma močī ne pa jokam... tobiš - es nesaprotu otro punktu - signal amplifier? vai varbūt tev vajag tieši pretēji? signāls baigi močī un trokšņi lieli - tāpēc klusumā kkādas indukcijas figviņzinkas..?
ā un otra lieta - esi mēģinājis to savu shēmu virtualizēt..? tobiš visupirms palaist projektu virtuāli uz emulatora kāda, kompī?
AtbildētDzēstĪsti nesapratu Tavu domu par to "pretēji signal amplifier".
AtbildētDzēstPalaižot audio no kompja, kad kompim skaļums ir uz max, neiedegas vairāk par 10 lediem (no 20). Tas ko es gribu panākt, ir lai ar vienu poci es varu regulēt ienākošo skaņas signālu no 0 līdz 20 lediem, neatkarīgi no tā kāda līmeņa audio nāk iekšā.
Par to gļuku, ka iedegas 20 ledi, kad ir izrauts vads, iespējams, ka tiešām tie trokšņi, kas nāk iekšā bez vada + signāla pastiprinātājs spēj iedegt visus 20 led. Man liekas, ka jebkurā audio ierīcē, ja izrauj jack konektoru, nostrādā kāds slēdzis, kas nogriež to ķēdi, lai nedūktu.
Ja tā padomā, tad man mašīnā nebūs momentu, kad vads būs izrauts. Tad, kad maģi izslēgs, tiks pārrauta strāva arī uz šo parikti. Tāpēc laikam to pat nav jēgas risināt.