Wrong buzzer type lot's of strange problems

[Wob]

Hi, first post. Great project!

My kids have been asking me to build this project for years. Finally got myself a 3d printer (COVID hobby) so this was the first project I used it for. It went fine (except the cap, but learned about z-hop and what not due to that, so good experience).

Self sourced all my stuff from local shops (which get it from china).

TLDR: The active buzzer module Ky-012 should have been passive like KY-006?  Caused all kinds of beeping/twitching/BT issues. Even curling up so I could not reach the off button and had to remove the battery. After removing the buzzer it all worked fine! 

Q1  all passive buzzer boards I find only use signal and ground. They have a 3rd pin, but it is not going anyware. Is this as expected? A the wiring schematic wires VCC from servoboard to buzzer module

Q2, Could using an active 3 wire instead of an passive 3 wire cause all of this? 

Q3, bit unrelated, but is there currently anyway to get the scratch part working? My son has this idea of an maze using an distance sensor and whatnot.

Long story

The sourcing and build went ok-ish, the servo's were supposed to be genuine (NOT) there was one bad behaving BT module. While waiting on replacement module we had some prefun with the demo mode.

The BT module came last week, paired it with the other one, got it into the gamepad and set the robot to RC. The Buzzer went on continously. Turned robot off and on, and no more buzz, pressed the DPAD move buttons and it worked. 

Pressing any other button (up, or the numbered ones) resulted in big beep, curling of robot, twitching of servo's and/or unresponsiveness (had several combinations).
After debuging the gamepad and double checking the BT modules I learned about the app. Same behaviour. So took a closer look at the robot. Replaced the nano with a spare, replaced the BEC, replaced the batteries. Was about to order a new motor shield when my wife asked me to please stop that bloody buzzer. So I decoupled it, and boom, no more problems, all worked fine. Plugged it back in and problems was back.

Turns out the buzzerboard was labeled KY-012 which is an active module. Should have been an passive. Does it make sense? Anyway looking for a replacement, cannot find anything which requires 3 wire. Just 2 (signal and ground).

Regards,

-Wilco

[elto...@gmail.com]

OMG, your wife is a genius ;D. I set up my vorpal in December, and I had the same problems reported by you. I replaced bluetooth modules, arduino, motor shield etc. I had practically given up. When I saw your email, I came running to disconnect the buzzer. And the RC mode worked perfectly. Thank you very much.
Now we just need to find a solution for the buzzer.

[elto...@gmail.com]

by the way, I'm using a passive buzzer labeled HW-508 (similar to KY-006). So, I believe that the problem is not the type of buzzer.

[Wob]

Glad it helped.

So I read up on buzzers. the active one I use draws too much current for the arduino, it also backfeeds in possible higher voltages that the poor nano can handle. I should be happy I did not fry anything.

Your passive module  only uses signal and ground as well (I did not find a datasheet, just examples where they only hook up the signal and ground)1, just as mine active one.

I found a couple of passive modules which truely use the VCC pin for driving the buzzer, using a transistor to limit current draw on the arduino pin.

They also seem to have resistor on the module in series to the signal pin.

With your module you could use a 300-1K ohm resistor in series from signal to arduino pin, and only connect signal and ground.

If it draws too much also the transistor, optional with diode could be a solution.

Some links:
https://startingelectronics.org/tutorials/arduino/modules/active-buzzer/

https://startingelectronics.org/tutorials/arduino/modules/passive-buzzer/

https://www.hlhv.nl/Webwinkel-Product-253453074/3.3-5V-Passive-Buzzer-Alarm-Module-Geekcreit-for-Arduino-products-that-work-with-official-Arduino-boards.html

https://www.hlhv.nl/Webwinkel-Product-253448299/Buzzer-Module-3.3V~5V-PWM-Digital-Input-Board-RobotDyn-for-Arduino-products-that-work-with-official-Arduino-boards.html

@Vorpal

As a suggestion, perhaps the wiki could be updated with this information. Also perhaps list the model of the module(s) which are proven to work.

Regards,

-Wilco

[elto...@gmail.com]

Hi, Wilco as you suggested, I removed the VCC cable and left only the signal and gnd cable on the passive buzzer. In addition, I placed the 1K resistor on the signal pin. Everything worked out perfect. The only side effect is that the speaker sound is very low, but there is still audible feedback. Thanks again for the help.

[vorpalrobotics]

Well it's cool that the community responded with a solution before I had a chance to!

Yes, using the plans as published it has to be a three pin passive buzzer module. There's a picture of the one we use right on the Bill of Materials section of the assembly instructions and it definitely says passive. The part number is typically marked KY-006 on places like aliepress of banggood. The 2 pin versions are just the buzzers themselves, not the module, and I assume they have a small transister or maybe an op amp inside. The module power comes from the SD Driver, just the signal comes from the Arduino when using a module. If you try to use a 2 pin buzzer alone (not a module) then the power is coming from the Arduino, which can only supply 30 or so milliamps before it browns out or burns up.

Note that we see about 1 to 2% of KY-006 buzzers defective when we receive them from our suppliers. I actually have an employee test every buzzer before they go in our kits, and we throw away the bad ones. They can be defective in a way that shorts out the nano, or they can be defective in a way that they produce almost no sound.  We do this with most of our parts to reduce the number of kits with defective parts to a minimum. In fact quickbuild kit electrical systems are 100% tested before they get packaged up.