Joined: Jan 14, 2010 Posts: 6058 Location: Moon Base
Audio files: 728
Posted: Sat Apr 26, 2014 7:50 am Post subject:
TV PCB lamp Subject description: not really musical, although,...
A project I started on years ago inspired by this video:
I used a PCB from an old TV with most of the (larger) components removed and besides a CFL I also added some flashing LED's to it. I glued the LED's
behind holes that were already in the PCB and made a controller using some of the components that I had removed from the PCB. (The opamps and
orange caps came from it and if I remember correctly the 4052 muxes aswell but I'm not entirely sure about that). I also wanted it to make some
kind of sound but didn't really knew how to do that at the time, which is one reason why the project was put on hold.
I was already thinking of finishing it when I started on my Frankensynth, but it was a video of a nice pinball machine lightbox that RingMad sent me
that gave me the final push (thanks James ). I retraced the circuit and drew a schematic to see what I had actually build . I probably
have one of it somewhere but this was a faster method then trying to locate that. The 2 opamp oscillators look a bit unusual to me, but I think
at the time I just searched for some oscillators I could make with opamps and that's what I found. The output appears to be a sine so I wonder if it's
some sort of resonating filter setup
Here are some photos. The handle isn't secured yet and I'm not sure if I will use it. Makes it easier to move around but I can't really place anything
on top it I do. Not really visible in the photo is the perspex front with protective tape still attached. The wood I used for the case (same as the
sides on the Frankensynth) has some grooves in it to hold it in place. In the photo it still had 2 seperate cables for mains power, one for the CFL
and one for the LED's, but it now has 2 switches and one cable.
up next: the added 'sound' part,..
PCB TV flash LED demo.mp4
Description:
Flashing LED demo (backlight turned off)
Filesize:
2.12 MB
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1106 Time(s)
PCB TV LED Flasher.gif
Description:
LED flasher circuit
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100.48 KB
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PCB TV - 01.jpg
Description:
PCB TV lamp
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70.09 KB
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PCB TV - 02.jpg
Description:
PCB TV lamp
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PCB TV - 03.jpg
Description:
PCB TV lamp
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Joined: Jan 14, 2010 Posts: 6058 Location: Moon Base
Audio files: 728
Posted: Sat Apr 26, 2014 12:05 pm Post subject:
So I wanted it to make sound, or use it as some sort of controller using the circuit that controls the LED's. I tried some different setups first using
more 4052's hooked up the same as the ones that control the LED's but with some resistors attached to it to create a control voltage. I also did
some test with shiftregisters and resistors but it didn't really sound like what I was looking for.
So my next try was using a sample and hold to create some nice random blips. I wanted it to be in sync with the LED's so it has to sample on every
change of one of the squarewave oscillators (low to high and high to low). To achieve this I used XOR gates with a small delay circuit (LPF) between
the two inputs. By adding a small capacitor in series with the output it creates a very short pulse on every transistion. Now that I think about if I
used smaller capacitors for the delay circuit I wouldn't even need those caps on the outputs well, anyway two pulses are mixed
together to control one S&H that samples one of the sinewaves, and this circuit is repeated twice, with the control signals (squares, sine) grouped
in the same way as the LED's. The outputs of the S&H's are mixed together to create a semi random stepped control voltage that varies
between 0-5V.
I could put a VCO in there a small amp and a speaker, the transformer is more then sufficient for that, but I'd probaby never use it. Maybe just a
simple VCO would be nice (it's just one chip and a cap), so i might add that. No sound samples yet but I will record a short demo.
PCB TV CV generator.gif
Description:
stepped CV generator
Filesize:
63.42 KB
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Joined: Jan 14, 2010 Posts: 6058 Location: Moon Base
Audio files: 728
Posted: Tue Apr 29, 2014 8:20 am Post subject:
Yeah the video should work, it's uploaded straight from my mobile phone without any editing or re-encoding.
I just tested the link and it plays fine in VLC. Maybe your download got corrupted ?
(I do have that happen occasionally when downloading from this forum). _________________ "My perf, it's full of holes!" SoundCloudBandCampMixCloudTwitchYouTube The Golden Shrimp Guild
good call, was trying to open in firefux (sic) browser. works with VLC.
Nice project as always PHOBoS! _________________ http://www.youtube.com/user/borisandfef
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). I retraced the circuit and drew a schematic to see what I had actually build 
. I probably
well, anyway two pulses are mixed
.
