General > General Technical Chat
Musical surprise
TerraHertz:
So, another day, another street-tossed large screen TV to disassemble. I like these very thin LCD side-backlit screens, and pick them up when I see them on the kerb. I have three or four (of their guts) now, with a project in mind to make a thin 'light table' using the side-illumination optics and LED drive electronics these provide.
The sticking point, is making a simple controller from an Arduino, to provide power on-off and LED lighting level control to the power supply board. Via whatever serial coms the TV uses between the main video board and the power board.
This is one I picked up on Monday. The usual - fractured LCD glass making interesting but useless patterns when turned on. Meaning the backlighting is working fine so go straight to disassembly.
Then turn it on again as bare boards on the bench, to see if the power board has a 'default LEDs on' mode if the main board is disconnected.
This one doesn't, but then... big surprise. After at least a minute it figures out it has been left on without a video source. Suddenly it starts playing music! A lengthy ambient piece, quite pleasant. Also the backlight LEDs fade up and down in brightness, matching the music.
What's good about that, is it means the LED brightness control serial line will be exercising continuously. All the better to protocol grab.
Speaking of which, it's about time I bought a modern small, relatively cheap lunchbox scope. One with various serial protocol capture and decode features built in. What models do people recommend? (He asks, hoping to avoid days and days of hunting and reading specs.)
Zero999:
I wonder if the audio amplifier is any use for a project? The speakers, tend to be pretty crappy, so no good in anything requiring decent sound quality, but fine for basic sound effects.
Regarding the oscilloscope, if it needs to be portable, go for the Owon SDS7102, with a battery. It isn't as good as the Rigol DS1054, which is a little more expensive, but I find the portability more of an advantage.
TerraHertz:
--- Quote from: Zero999 on March 17, 2021, 10:57:57 am ---I wonder if the audio amplifier is any use for a project? The speakers, tend to be pretty crappy, so no good in anything requiring decent sound quality, but fine for basic sound effects.
--- End quote ---
If you needed a speaker driver amp with only digital audio input, perhaps. Looks like that area of the PCB could be cut free and used by itself. The IC:
TI TAS5707
20-W STEREO DIGITAL AUDIO POWER AMPLIFIER WITH EQ AND DRC
https://www.ti.com/lit/ds/slos556b/slos556b.pdf
--- Quote ---Regarding the oscilloscope, if it needs to be portable, go for the Owon SDS7102, with a battery. It isn't as good as the Rigol DS1054, which is a little more expensive, but I find the portability more of an advantage.
--- End quote ---
Actually for something like a scope, I'd avoid batteries. Just one more thing to go bad. Don't need portability, it will always be used on a bench or close to power.
So far I can't see a list of serial protocols for the Rigol DS1054. I haven't paid much attention to new Rigol/Hantek scopes (or HP/Tek for that matter), but I do recall reading something about a model that could capture and decode many different serial bus protocols. Sometime in recent years. That's a major attraction for me.
Btw the TV was a TCL model 50P6US. Having a quick skim of the user manual (dl'd) just reminds me of why I avoid owning a TV these days.
tunk:
No expert, but for an inexpensive DSO, you could look at the Hantek
2000 series which comes with RS232/UART, I2C, SPI, CAN, LIN decoding.
http://www.hantek.com/products/detail/17182
tautech:
THz, will a 2ch DSO be adequate ?
Have a look at the 200 MHz SDS1202X-E.....SPI, I2C UART, CAN and LIN decodes as standard....and BTW don't let anyone tell you you can't decode SPI with a 2ch DSO as Clk Timeout settings allow expressly this.
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