Alarm buzzer

Gary V

TVWBB Fan
quick question about this. Looking at past posts i have been trying to find out if while booting up, does the buzzer buzz. If it is supposed to then i come to the next question. The only way i have to test the buzzer is with my scopes 1volt p-p square wave calibration source. I can hear the buzzer, but it`s pretty faint. Anyone out there tested a buzzer using their scope calibrator and how loud was it when they tested it this way.

Reason for this dumb question is when i am outside, i would like to set the audible alarms to let me know if i have a problem.
 

Steve_M

TVWBB Guru
The buzzer shouldn't be activated while booting. You should be able to test the alarms with the "test" buttons in the Alarms section. The buzzer should be plenty loud. I find it annoyingly loud, so I don't even solder it onto my board :)
 

Gary V

TVWBB Fan
thanks Steve. I have never heard my alarm go off ever, and when i use test buttons, it does not alarm. I am suspecting the buzzer since even with the 1vp-p calibration reference used to activate it when removed, it should be louder than the faint buzz i get right now. BS170 measures fine , so i will set scope up and play around with the alarm trigger on the alarm page. Did order a couple of buzzers, so if circuit is working without alarm, then i can install one when they arrive. If too loud and i do not like it, i too will remove and just send alarms to computer and phone
 

Steve_M

TVWBB Guru
You need to drive it with a signal, not just voltage. I'm pretty sure the HM uses a 4KHz tone for it
 

Gary V

TVWBB Fan
i agree that i need to test with a signal. Thats why i tested the alarm buzzer with my scope calibrator which has a 1khz square wave at 1 volt level. Like i mentioned before, with the 1 volt calibration voltage i could hear a faint 1khz tone. Really low level because alarm buzzer needs a square wave of 3 volts for a loud enough level to be irritating. Where i am now is the system log says the alarm is ringing, but the alarm buzzer is not. So far i have not hooked scope up because it`s battery is low. Maybe tomorrow. With freq counter, when triggered i do not see a 4khz pulse train. I suspect it should last at least a second. Q2 from meter testing looks good. Voltages match what is shown on board diagram for 4.3.3 control board. I have ruled out the 328P chip by replacing with a never been installed chip. same results. So that leaves either the BS170 is bad which i am confident it`s good or maybe i am still setting up the alarms incorrectly. With the system log saying i am getting alarm triggers, i am now scratching my head a little more. I still suspect that the buzzer should be much louder even with the 1volt sqaure wave. Will have a new one next week.
 

Steve_M

TVWBB Guru
If the alarm is firing from the HM and you see voltage across the pins of the buzzer, but the buzzer isn't doing much of anything, my guess would be that the buzzer is faulty.
 

Gary V

TVWBB Fan
will see what the ATM chips shows when i get the battery charged up on my scope. I am hoping to see the same results on the scope as the log shows. Alarm buzzer triggered. There is always voltage across the buzzer, 1k resistor, it just pulses when the ATM send pulses to BS170.
 

Gary V

TVWBB Fan
So got the alarm stuff working. I guess i did not interprete how it works per software, versus how it did work when setting up. What i failed to do was to make changes to probe 0 when i had it selected. I assumed that whenever you toggled test key, not only does the log say you trigged the alarm, but i expected the alarm to sound. There is a bunch of conditions that had to be met to make audible alarm work. I like the feature, but testing the windows that you set up is a pain. I t would be nice to have either the alarm beep during boot, to let you know it functions, or another selection for the test key that generates a system log and audible alarm too.
 

Bryan Mayland

TVWBB Hall of Fame
Ironically, the "Alarm Test" button never makes the alarm beep, it just tests the actions you have selected. It's been something I've wanted to add for a while but wasn't sure where to put it, since when I solder HeaterMeters, I never test the buzzer as part of the testing procedure and it always bothered me.

I've posted a new AVR firmware 20200715B that now has a buzzer test in the engineering debug menu on the device itself. To get to this menu, use the right button until you get to "Manual Mode?" then hold the left button until the display changes. It starts in Pit Probe Debug so just go left one time to go to Bandgap / FanFeedback / Button Debug and the buzzer will beep for 200ms. Each time you enter this menu it beeps. I've also bundled this in the latest snapshot firmware image.
 

Gary V

TVWBB Fan
Thanks for the follow up Brian. Will update to latest image and test it out. Currently going through some thermocouple issues. All of them are flakey so made a couple from my stash of Kapton high temp couple wire. So far I have learned that they are accurate, but the response time is faster than the heatermeter thermocouple input tc. Will try with a piece of Kapton tape on weld. that should slow it down enough to use
 

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