After a 2 year on and off battle with these power meters ive fought with from badly failed microcontrollers to descretes to comparators, ive decided to go back to the LM3915 for my amplifier build that i have all but forgotten about.
Heres what i have drawn up so far.
[IMGDEAD]https://imgur.com/a/EfbOr1F[/IMGDEAD]
Ive really just been copying right from the datasheet.
Im going to cascade 2 of them but only use 15 levels. im having trouble with these parts, i want to meters to run on BAR MODE. heat dissipation isnt an issue i can slap some heatsinks onto the chips. 2nd is the rectifier AND "sensitivity" adjust to connect it to speaker level, about 200W into 8Ohm or 40V RMS (higher than the IC can take)
For the rectifier i was looking at "Figure 18 Precision half-wave rectifier" from the datasheet then i get stuck on what op amps to use because the LF351 isnt around anymore and it has to run on a single 12V rail.
Another issue that might be with that rectifier, maybe not but is with the rubbish ebay bit a have is low frequencies like 40Hz the entire bar can be easily seen flickering with the AC signal. i was able to fix it on a breadboard with a 22uF cap and a 1.5K resistor on the signal input to act as a filter.
Another part but isnt a must have is the brightness control seen in Figure 25. I Believe this allows me to adjust current for ALL LEDS at once for a brightness adjust but im not certain
The plan in the end is to get PCB's made and hopefully finally have a design that works like ive been planning for months and months
Heres what i have drawn up so far.
[IMGDEAD]https://imgur.com/a/EfbOr1F[/IMGDEAD]
Ive really just been copying right from the datasheet.
Im going to cascade 2 of them but only use 15 levels. im having trouble with these parts, i want to meters to run on BAR MODE. heat dissipation isnt an issue i can slap some heatsinks onto the chips. 2nd is the rectifier AND "sensitivity" adjust to connect it to speaker level, about 200W into 8Ohm or 40V RMS (higher than the IC can take)
For the rectifier i was looking at "Figure 18 Precision half-wave rectifier" from the datasheet then i get stuck on what op amps to use because the LF351 isnt around anymore and it has to run on a single 12V rail.
Another issue that might be with that rectifier, maybe not but is with the rubbish ebay bit a have is low frequencies like 40Hz the entire bar can be easily seen flickering with the AC signal. i was able to fix it on a breadboard with a 22uF cap and a 1.5K resistor on the signal input to act as a filter.
Another part but isnt a must have is the brightness control seen in Figure 25. I Believe this allows me to adjust current for ALL LEDS at once for a brightness adjust but im not certain
The plan in the end is to get PCB's made and hopefully finally have a design that works like ive been planning for months and months
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