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 Forum index » DIY Hardware and Software
LED-O-SCOPE
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PHOBoS



Joined: Jan 14, 2010
Posts: 5591
Location: Moon Base
Audio files: 705

PostPosted: Sun Jan 26, 2014 8:39 am    Post subject: LED-O-SCOPE
Subject description: low resolution oscilloscope
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In 2012 I used a mini portable TV to create the Dronoscope and I kept the backcover of the TV for some future use, maybe for a synth or something.
I came across it again while looking for a suitabe housing for a project and when I saw it I got the idea to combine it with something else I had still
laying around: a 10x10 LED matrix that I soldered up > 10 years ago.

Originally I made it to be used for an audioscope circuit using 2 LM3914's, but I never got to that (probably because the LM3914's were too expensive).
So I looked on the web for some inspiration for what I could use it for which led me back to this site, and this thread where Fenris posted the following
schematic:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

So I gave that a try it and worked pretty well. Very Happy
But the input needed some boosting and I wanted it to be usefull with AC and DC signals (positive and negative), external time (X) input, a better
offset control and see if I could make it somewhat useful to measure a voltage too.

X / time section:
I started with an oscillator made with a 40106 followed by another inverter as a buffer. The output is connected to the switch contact of the X-in
jack, buffered by a transistor (so it can be used with lower input sgnals) and then turned into a pulsewave which is fed to the CLK input of the 4017.
I used the reset input for the hold switch instead of the clk enable input so when put on hold it will always stop on the first column. The sync input
was added because I had a spare opamp and inverter and it's made with a comparator buffered by the inverter to get a clean CMOS signal. This is
then turned into a short pulse to reset the CD4017.


Y / input signal section:
There's an attenuator on the input for a wide voltage range, followed by a voltage divider which pulls the voltage up. This way AC and negative DC
voltages can be used aswell. I added diodes for protection but they're probably not necessary with the 1M input resistor. The signal is buffered
by opamp u2a and then amplified (+ inverted) by opamp U2d. According to the dataheet the LM324 can swing between 0V and Vdd-1.5, so with a
9V supply that woud be 7.5V, I choose 7V to be sure and biased the opamp at ±3.5V. The signal is then amplified some more by opamp U2c
and this one also has offset control. The offset control is needed for negative DC and AC signals and there's also some offset change when the
input signal is attenuated so that can be corrected aswell. There also a capacitor in the feedback loop to create a lowpass filter which is mostly
there for when it's used as an audioscope. But it also creates nice vertical lines on squarewaves Laughing The output then goes to the input of
the LM3914 that is set to a range of 0..5.1V (zenerdiode).

There's a 9V regulator on the DC input to provide a stable voltage and to make it somewhat useful to measure a voltage I made it so that with an
unattanuated input signal the full range is 1V, and there's a difference of 0.1V between every row. But I'll probably use it as a nice audio visualizer
most of the time Shocked


PHOBoS - LED-O-SCOPE.gif
 Description:
LED-O-SCOPE schematic
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PHOBoS - LED-O-SCOPE.gif



LED-O-SCOPE - 01.jpg
 Description:
TV housing
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LED-O-SCOPE - 01.jpg



LED-O-SCOPE - 02.jpg
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TV housing
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LED-O-SCOPE - 02.jpg



LED-O-SCOPE - 07.jpg
 Description:
LED-O-SCOPE front
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LED-O-SCOPE - 07.jpg



LED-O-SCOPE - 08.jpg
 Description:
LED-O-SCOPE back (with sync input and trig. level control)
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LED-O-SCOPE - 08.jpg



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Last edited by PHOBoS on Sun Jan 26, 2014 2:26 pm; edited 4 times in total
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PHOBoS



Joined: Jan 14, 2010
Posts: 5591
Location: Moon Base
Audio files: 705

PostPosted: Sun Jan 26, 2014 8:42 am    Post subject: LED-O-SCOPE
Subject description: wiring pic and animated gifs
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wiring pic and some animated gifs Laughing


LED-O-SCOPE - squarewave.gif
 Description:
LED-O-SCOPE - squarewave (animated)
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LED-O-SCOPE - squarewave.gif



LED-O-SCOPE - sinewave.gif
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LED-O-SCOPE - sinewave (animated)
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LED-O-SCOPE - sinewave.gif



LED-O-SCOPE - 04.jpg
 Description:
wiring pic for RingMad
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LED-O-SCOPE - 04.jpg



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Cynosure
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Joined: Dec 11, 2010
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Location: Toronto, Ontario - Canada
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PostPosted: Sun Jan 26, 2014 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

You are my hero. Hail the Master
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isak



Joined: Dec 13, 2009
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PostPosted: Sun Jan 26, 2014 1:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi PHOBos

Ones I thought your crazy, now I know your crazy!
Beautyful piece of work!

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PHOBoS



Joined: Jan 14, 2010
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Location: Moon Base
Audio files: 705

PostPosted: Sun Jan 26, 2014 1:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

thanks jake,. and it isn't even valentines day yet Razz

isak wrote:
hi PHOBos

Ones I thought your crazy, now I know your crazy!
Beautyful piece of work!


Laughing thanks,.. check the build thread in about 5 minutes from now,. just to make sure Wink

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LFLab



Joined: Dec 17, 2009
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Location: Rosmalen, Netherlands

PostPosted: Mon Jan 27, 2014 4:09 am    Post subject: Reply with quote  Mark this post and the followings unread

effing great! That's really nifty.
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RingMad



Joined: Jan 15, 2011
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PostPosted: Mon Jan 27, 2014 11:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Cynosure wrote:
You are my hero. Hail the Master

Mine too!

James
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analog_backlash



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PostPosted: Wed Jan 29, 2014 8:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Sorry for the late reply PHOBoS. It looks great! I remember buying an electronics magazine (in the '80s) which had a very similar idea, but I was put off by the thought of buying 100 LEDs Laughing . They were much more expensive then... I've long since lost the mag, so thanks for the schematic. I suppose that you could extend it by cascading 4017s and LM3914s (but the LED count then rockets upwards).

Gary
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PHOBoS



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PostPosted: Thu Jan 30, 2014 12:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

thanks James, Gary Very Happy

Yes, it could be extended, some extra 4017's would be pretty easy but adding
more LM3914's would need some changes to get the full range. Also with
more 4017's the LED's would be less bright, you could increase the current,
but if the clock is turned off and there is no signal only 1 (or 2 depending on
the offset) LED is on, so you can't make the current too high.

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SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube

Last edited by PHOBoS on Thu Jan 30, 2014 6:46 pm; edited 1 time in total
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JovianPyx



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PostPosted: Thu Jan 30, 2014 6:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice work. I like the look from the back too. Fun stuff to be sure.

I have a 256x128 black and white LCD...

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roglok



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PostPosted: Tue Feb 04, 2014 10:49 am    Post subject: Reply with quote  Mark this post and the followings unread

BEAUTIFUL!
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KnobHell



Joined: Jan 28, 2012
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PostPosted: Sat Feb 08, 2014 10:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Very cool
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The Bad Producer



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PostPosted: Sun Feb 09, 2014 6:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Wow Very Happy I love that!
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