Electronics > Beginners
Is this ultrasonic insect repeller actually ultrasonic?
Zero999:
--- Quote from: John_doe on June 27, 2019, 02:42:09 pm ---
--- Quote from: Zero999 on June 27, 2019, 09:10:46 am ---You'll need to connect this circuit via an isolation transformer or use a differential probe, to safely connect the circuit to an oscilloscope.
--- End quote ---
I have neither...
What will happen if I just connect the DSO138's terminals across the piezoelectric transducer? Of course, I will do it very safely - I will solder leads to it and affix everything with good isolation before I'll connect it to the power.
I should also mention that the DSO138 is not a normal scope, it's more like a toy, and mine is powered from a battery and is not connected in any way to the house earth/ground.
--- End quote ---
That's a bad idea. The oscilloscope will float at the mains voltage and could give you a nasty shock, if you touched it.
How about placing a microphone and amplifier near the piezo and looking at the waveform with the oscilloscope? That's much safer and will actually show you the sound wave being produced, rather than the electrical signal to the traducer, which might not match it perfectly.
Ysjoelfir:
--- Quote from: John_doe on June 26, 2019, 09:09:02 pm ---
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Hey, that thing is gorgeous! Its Nno toxic, environment-triendly, Sare and dorless! :-DD
Also it is moisture proof and waterproof, but don't clean it with water or a damp cloth, it may break!
And don't forget to not make strong striking on it. Not-so-strong striking is ok.
:-DD
What a pile of crap. Dispose of this thing, the best it will do is light up your friends house.
John_doe:
--- Quote from: Ysjoelfir on June 28, 2019, 07:01:59 am ---Hey, that thing is gorgeous! Its Nno toxic, environment-triendly, Sare and dorless! :-DD
Also it is moisture proof and waterproof, but don't clean it with water or a damp cloth, it may break!
And don't forget to not make strong striking on it. Not-so-strong striking is ok.
:-DD
--- End quote ---
That's standard Chinglish, I've grown used to it by now so it's barely amusing (Well, except for this photo from a hospital in China which had me laughing out loud).
--- Quote from: Ysjoelfir on June 28, 2019, 07:01:59 am ---What a pile of crap. Dispose of this thing, the best it will do is light up your friends house.
--- End quote ---
Unfortunately, it is not mine to dispose of.
--- Quote from: Zero999 on June 27, 2019, 08:58:40 pm --- That's a bad idea. The oscilloscope will float at the mains voltage and could give you a nasty shock, if you touched it.
How about placing a microphone and amplifier near the piezo and looking at the waveform with the oscilloscope? That's much safer and will actually show you the sound wave being produced, rather than the electrical signal to the traducer, which might not match it perfectly.
--- End quote ---
Thanks again Zero999, I took your suggestion and tried to connect an electret microphone to my scope but I struggled to get a clean signal. Nevertheless, even with a "dirty" output you make out enough:
It looks like the signal is occurring every 5 divisions, so, exactly 100Hz (2ms per division), but the signal isn't clear enough to differentiate 1 cycle of the resonant frequency, even though 0.25 of a division (2KHz) seems about right.
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