Timed LED lights (like drag racing "Christmas Tree" starting lights)

Thread Starter

CaptStephan

Joined Feb 14, 2018
34
Hello,

I am new to the forum and have searched several places with no luck. I am an engineer, but not electrical, so have basic understanding of circuits, but could really use some help on this little project.

I am trying to create a series of LED lights that count down to a start in about 3 seconds or so. It would need to be adjustable a bit to make this work. Here is the actual project detail:

I have a deaf dog that loves chasing small tennis balls. She is pretty obsessed about it and we purchased a iFetch electronic ball thrower. She can bring the ball right next to it, and has put the ball in it a few times. The disconnect is that the device uses sound to indicate when the ball is about to be thrown. Other dogs use that as a cue, but she can't hear it. I want to connect a circuit to the existing device and have a set of LED's light up when she drops the ball into the device, then a series that "counts down" to when the ball is thrown. If you are familiar with the way drag racing is started, it would be similar.

If someone could point me to a reference or sketch up a quick circuit if you have that skill set, it would be most helpful and I would be very grateful.

The device has a standard US 120 volt plug / transformer that outputs 9v at 3A. I am assuming I can simply tie into the existing circuit that has the beeper. Photos show the device and the LED's on the back that indicate if it is on low, medium, or high. It doesn't look like I can post photos yet, so you can see the gadget on the manufacturers site here: https://goifetch.com/products/#ifetch-original
 

dl324

Joined Mar 30, 2015
9,111
I don't recall how drag racing lights sequence...

You could use a 555 timer to drive a CD4017 if you want a moving dot display or a CD4015 shift register if you want bar display.

You can adjust the timer for the desired timing, but the first interval is longer than the rest. That can be addressed if it's an issue, but it adds to circuit complexity.
 

Wendy

Joined Mar 24, 2008
21,906
Or You can do what #12 did and give me shout. I would be glad to help Early requirements needing to be determined. Power supply(Batteries? almost any thing will work.LEDs or Light bulbs? You will need a555 IC and a 4022 or a 4017 IC.Then there is the breadboarding technique you are most comfortable with.I once built a light tree for my combat robotics days (some one has to build infrastructure). Since dogs don't see colors light position is more important Maybe a heavy duty vibrator he can feel?

LEDs, 555s, Flashers, and Light Chasers
[URL='https://forum.allaboutcircuits.com/threads/wendys-index.112710/']Wendy's Index
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[URL='https://forum.allaboutcircuits.com/threads/wendys-index.112710/'][/URL]
BtW , Welcome to AAC!
 

#12

Joined Nov 30, 2010
18,159
IIRC, Drag racing lights go:
Red = You're in the "start" position.
Add a Yellow
Add a Yellow
Add a Yellow
Add a Green:eek:

This might or might not be exactly what CaptStephan (and his dog) wants. That is why I call this process a conversation.;)
 

Wendy

Joined Mar 24, 2008
21,906
Many deaf people enjoy feeling music via the vibrations they can feel. Depending on your floors you might be able to have a speaker face down an your pooch will pick up vibration through her paws dogs are smart critters Even a small transistor radio on her collar might que her. Low freq buzzes can be felt quit easily.I too am a dog person, so this promises to be fun.
 

Thread Starter

CaptStephan

Joined Feb 14, 2018
34
Some great ideas here! Thanks everyone.

Here is the sequence I promised, albeit a very bad drawing. It is very much like the racing light sequence above.

Some extra info, not necessarily required for the project:
  • The dog in question is a mini Australian Shepard female. Due to a bad breeder, she is deaf and a little smaller than she should be.
  • She is called PJ (short for Maison Perrier-Jouët) - all our female dogs are named after wine ;-)
  • She does respond to vibrations in the floor, but they sometimes seem to scare her.
  • She does know hand signs that I made up (nothing too official).
Thanks again everyone!!
 

Attachments

dl324

Joined Mar 30, 2015
9,111
What will trigger the timer? You show 7 or 8 LEDs (engineers notice things like that); which is it? What do the three dots represent? And the dot in the center of the ring of 7 or 8?

Since you want all of the LEDs on with them turning off one by one, that eliminates CD4017 and 4022.

Now we need to know your brightness requirement for the LEDs, and the color(s).
 

AnalogKid

Joined Aug 1, 2013
8,137
Looks like a 7-stage Johnson counter, with diodes OR-ing some of the stages together into the light groups.

What synchronizes the sequence to the ejection? If the beeper starts the sequence, is the idea that the sequence runs at a fixed frequency that is tuned to match the delay between when the beeper starts and when the ball is ejected?

I see the light groups like this. the circle is three groups, the two dots are the 4th, and the last dot is the 5th

All Off
Start
1 + 2 + 3
2 + 3
3 + 4
4 + 5
5
all off = eject
Stop

using a driver transistor array makes for less work:
1 - CD4093 - oscillator and control flipflop
1 - CD4017
1 - ULN2804
2 - 2N7000
something to detect the beep and set the flipflop. 4017 output 6 resets the ff and the 4017.

Are you thinking of detecting the beep with a small microphone or by direct electrical sensing of the beep signal?

ak
 

Thread Starter

CaptStephan

Joined Feb 14, 2018
34
Wow! Lots of info here. I will try to gather the parts for the set-up mentioned above. I was not really particular about the number of lights per stage, but I will work out what fits best and get back to everyone. I think the brightness will be limited to the power available in the device - right now that is 9v from the included transformer.

For the trigger, I was thinking wiring directly into the beep, so a hard wired start. That seems simpler to me, but let me know if I am off on that.
 

AnalogKid

Joined Aug 1, 2013
8,137
1. Check the wall wart to make sure the output is DC, not AC. There are many different markings, but we work well with photos.

2. For direct connection to the beeper signal we have to know what that signal is. The two options are DC switched on and off (because the beeper device has an oscillator built in), or a beeper signal, usually a square wave around 2 kHz.

3. For either of those options we need to know the signal amplitude and its relationship to ground. For your device, ground probably is the 9 V return lead. It might be marked as - or -9V, but that can be confusing in a world where there can be a true -9 V source.

ak
 

Wendy

Joined Mar 24, 2008
21,906
I've been thinking about how to trigger this gadget. I s there an LED that when this gadget starts it internal count down lights up?​
 
Last edited:

AnalogKid

Joined Aug 1, 2013
8,137
I was not really particular about the number of lights per stage
The most simple would be either up to 8 LED groups that did not overlap (no two groups on at the same time), or up to 4 groups with only two overlapping at one time:
1
1 + 2
2 + 3
3 + 4
4
Each of these options needs a max of 8 drivers, the number in one package.

If you do something like 5 groups of LEDs that do not overlap, that leaves two sections of a ULN2004 (7-transistor array) free to amplify or buffer the beeper signal in case something is needed, or act as a mic preamp if you decide on non-contact sensing.

ak
 
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