![]() I was not sure on how to accomplish this because of the current (amperage) needed but I decided to experiment and see what would happen. 3) Finally I thought that while the buzzer is working, it would be nice to light up some red leds also. ![]() In haste, in one of the positions of the switch I had to do nothing and the resistance was already the needed for one of the positions in the other position, the additional resistors would be in series with the base ones and the sum of them would give the value needed for the second circuit.Īctivities 1 and 2 are depicted in the picture. Then I've added a single switch (2 circuits - one for the timer and the other for the buzzer) and according to the switch position I've added the remaining resistors to have the maximum value of ohms needed when the switch was on each position (either Timeout or Warmup). Then I've looked for the equivalent fixed resistors and I've chose the minimum value needed for each circuit. I started by measuring the variable resistors value in each circuit to get the number of ohms needed at each circuit. ![]() I had some old leds at home, I've checked online if the voltages were the same and as they seemed to be, I just replaced the red led for the green led.Ģ) The second thing I did (and in order to reduce costs) was to try to do both the Timeout and Wamup settings using just a single circuit. I thought a green led showing it is working would be nicer. The video shows the final outcome.ġ) The kit had a red led that lights when it is counting down. If I was doing it for the Timeout counting, I might as well include the Warm-up period in the same device. Remember I wanted this to be very low cost, so the compromise I did (low cost assuming I don't have the visible countdown) seems pretty acceptable to me. This is even more important when sometimes some referees may be amateur (and perhaps shy), and they lack the authority to force athletes to respect the rules, so this will naturally help. I consider that the most important thing is to warn the players when the time is up. My approach does not include the visible count-down. The natural choice would be to use an arduino but to be honest I haven't done anything on that field yet, so I started a different route and used a 555 timer integrated circuit from a DYI kit that I found online. Being a maker, but not someone skilled enough in electronics, I had to find a way to speed up the process. ![]() So I decided to give it a try to build my on. Such a timer costs around $300 which I believe is bloody expensive. We can see examples from some of the most know brands in this sport in the pictures. That Timeout box basically is a timer of 60 seconds with a countdown. In bigger / richer clubs, whenever there is a timeout, the referee will put a Timeout Timer at the table. In table tennis, commonly know as Ping-Pong when practiced only for leisure, athletes have 2 minutes for the warm-up and 1 minute whenever they ask for a timeout (and each athlete can ask for one per match). HDRI Haven – CC0-licensed panorama skies.I practice Table Tennis at a local club called SC POVOENSE, in the beautiful city of Cantanhede in the centre of Portugal. ![]()
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