Build Your Own Countdown Regatta Box




An countdown "box" is a box with horns. When a regatta starts the box sounds the horns at predetermined intervals: 5 minutes before the start, 4 minutes before the start, 1 minute before the start and at the instant of the start. There are two types of sequences: 3 minute and 5 minute. In this instructable me and Chris LaBorde will show you how to build one by yourself. Because marine salt and water environment of boats, the box must be at least splash proof. Using the box will release two volunteers.

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Step 1: Components Needed

This photo shows an LCD shield and one realy module.

Arduino UNO from dfrobot

One LCD Shield from (see photo)

Two relay modules from

One YUASA deep cycle 12 V 7A battery

One charger for the Battery of 8A

One piezo buzzer

Three push connect only switches

One toggle switch

One on/off interrupter

One splash proof box

A set of two horns and a compressor with the air tubes.

One Tupperware small

Cables, shrink tubes, solder (optional)

Step 2: How to Charge

1. Open the box to charge the battery when needed.

When battery charging push the red toggle switch to charge mode. When not charging push back to 'normal'

Step 3: How to Use

The big green button starts the countdown.

The small button sounds the horn manually (override in case of emergency)

The yellow button inside the box toggles the sequence type between: three minute countdown or five minute countdown.

Step 4: How to Wire

1. Stack the lcd shield on the arduino board.

2. Connect the relays inputs to pins D11 and D2, connect relay D11 to piezo and D2 to the compressor.

3. Connect the big green button to the lcd push buton 'LEFT' (solder cables to the switch pins in the LCD board, the push button will override the lcd 'LEFT' button)

4. Connect the yellow push button the the lcd push button 'SELECT' (same as 3)

5. Connect the small green button between compressor + and battery + poles (to sound it manually)

6. Connect battery to charger via the red switch and baterry to compressor and arduino power input via the 'normal' position of the red switch.

Step 5: The Splash Proof Box

Find a splash proof box with rim seal. Use foam at the bottom so nothing is loose. Once the wiring is done put the Arduino and relay modules inside a Tupperware for added waterproofing. Make holes for the tubes that power the horns. And fix the horns as in the picture.

Step 6: Programming the Arduino

To program the Arduino: Download the Arduino IDE to your laptop. Upload the code to the Arduino with a usb cable. Source is here: the time units is 100ths of second and the time resolution < 10ms approx.



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20 Discussions


Reply 4 years ago on Introduction

The layout is Chris design. Now we are working on a leaner version with no battery. We shoudl attach a sticker that says "sounds hazard - wear protection" LOL


Question 7 months ago on Introduction

I’m building the Ollie regatta horn. I’m having trouble uploading the code (sketch 8a912bc) to the Arduino Uno. It keeps giving me multiple errors that a function definition is not allowed before ‘{‘ token.
it’s a straight upload of the Audrini.ino file (not the “production” version.).

It creates an error every time there is an opening bracket ‘{‘ in a definition line, such as at
Line 138. void mymenu(){
Line 171. Void activate_sound(int a) {

I’m surprised the compiler doesn’t accept the audrini.ino file. I even reloaded the Audrino IDE software and tried again on both the audrino.ino and the production files found on Instructabless.
any ideas?

2 answers
Jose OriolLTaorasbk

Answer 3 months ago

Becuase raspberri pi has become so convenient to program -- I think its better to move to Pi... in the next iteration I ll try to implement in pi. What version of arduino are you using?

TaorasbkJose OriolL

Reply 13 hours ago

Jose, Thank you for your reply. I'm using the Arduino UNO, but I'm not sure which version, I thought they were all the same. I know virtually nothing about the UNO or writing code.
I worked out the download issue I had and was able to watch the countdown sequences on the screen. So I know the program works, although slightly different than the sequence we use on Lake Erie. I had a few glitches in that the 5 min seq could not be restarted (would default to the 3 min seq) and the buttons on the UNO did not seem to correlate to the program. Unfortunately I ruined the UNO board while soldering wires to it. A replacement board did not function exactly the same way upon booting up. That's when sailing season started here (Ohio, USA) and I put it all away for the summer. I will return to it in the fall after sailing season. I have all the components and look forward to completing it.
I just learned of the Raspberry Pi - my brother gave me one. But I know nothing about them. I'll keep tinkering with the Uno because I think I'm closer to completing the horn with it instead of switching to the Pi.
Warmest regars,


Question 1 day ago on Introduction

Can I program any sequence of horn blasts?
What Amp for the relay module?


4 years ago

Love this and would like to make one for my club. I'm good with the wiring, but not code writing. Your code for the 3 minute start seems to be different than what we use. We use 3 long blast at 3 mins, 2 at two mins, 1 long 3 short at 1:30, 1 at 1 min, 3 short at 30 secs, 2 at 20 secs, 1 at ten secs, and count down from 5 secs to start. Could you lead me through changing the code to achieve this. Thanks for any help

4 replies

Reply 3 years ago

modify the vector

unsignedlong sch_3[] <-- indicates horn or buzz time in 10x ms units

h_or_b3[] <-- code: buzz = 0, short horn (sh) = 1, long horn (lh) =2 extralong horn 3


Reply 1 year ago

Ryan's 3 min. ver should be the standard 3 min start. Also, we and most clubs roll over the 5 min start, with no break. The start horn is the next class's 5 min horn, and it continues that way until stopped.

Can you modify code for each change?


Reply 1 year ago

I made the code changes for the 3 minute start and works well. Had no reason for the rolling five as our club doesn't use. I will need to see if I can find which drive i stored it on. If I locate I will post.


Reply 1 year ago

Thanks Ryan. A rolling 5 should be standard code, and in your case just turn it off after first start. We start 5 classes on Thurs, and JAM and Race on any weekend. I'm not a coder, but should be just a couple of lines?


1 year ago

I have succesfully loaded the program onto the Arduino UNO3. The problem is where do i solder the pushbuttons to on the LCD screen. I know that the select and left switches do all the nessasary functions, I just need to wire the momentary push buttons and am not a computer expert but the soldering is no problem. help me with a simple diagram, or do I solder to the pins on the back side of the board behind the switches? It appears that each switch has 4 pins or is A0 used with other connectors on the LCD board.

1 reply

Reply 1 year ago

Solder your momentary Switches to the back of the LCD Shield on the points next to the board edge. You don't need to do anything with A0


1 year ago

I notice that you've not bothered with a schematic... is there one?


2 years ago

This is great but our club uses a combination of lights and horn. I wonder if I could modify this to do our start sequence?

Advance Notice - Two lights flashing and repeated hornApprox 1 minute before warning signal (short duration)

Warning- One light, single horn and flag 5 minutes before start

Preparatory - Two Lights, single horn 4 minutes before start

One Minute - One light, single horn 1 minute before start

Start - No lights, single hornAt start

1 reply

Reply 2 years ago

Hi I am also wanting to build start regatta system to include lights and horn, very similar to your start sequence New to electronics and will be buying first UNO

if you move forward with your project let me know :-)


4 years ago on Introduction

Thanks so much for posting this. Going to make one for our J/22 class and if successful one or two more for our junior program. Im pretty good with mechanical things but have no experience with electronics. I've tried to source all the things on your list - but there are a lot of options for each item. Would you mind proofing my shopping list to be sure Im buying the right components? Here is a link to the list I've assembled with SKU's on each item (you can comment on the document)

Also I couldn't find the "on/off interrupter" for the toggle switch -there are many options - could you give me the details on the toggle switch?

Thanks again


3 replies