Need guidance- Ultrasonic Humidifier Circuit Build

Thread Starter

cbrcco

Joined Feb 22, 2017
3
I need some advice. I am using the ceramic disc transducer at the first link below and built the circuit at the second link already. I connected everything up and re-checked my soldering for mistakes but haven't found any. When i plug the circuit in, I can measure voltages across different passive devices but I'm not getting any resonance from the transducer when it is placed in water. I do have the two water leads placed in water as well. I'm thinking I may not have enough amps to make this circuit work. But frequencies generators aren't my forte so I wanted to confirm with the community that this circuit will even generate the 1.65 Mhz needed for the transducer. I'm currently using 24vdc to power this circuit. The attachment i have is another circuit I was thinking about using for this circuit but I'm surprised at how different the designs are from each other. It is simple and also driven by 24vdc.

Transducer
http://www.farnell.com/datasheets/81205.pdfhttp://www.farnell.com/datasheets/81205.pdf

Circuit created
http://www.electro-tech-online.com/attachments/atomiser-driver-jpg.58313/

Thoughts on second circuit is the attachment.
 

Attachments

DickCappels

Joined Aug 21, 2008
6,374
Farnell won't let me see the specs for the transducer. Ways around this are to upload the file or link to the datasheet at a new location.

You show two driver circuits (one at a link the other attached) and they are different. Which one do you plan to use?
 

Thread Starter

cbrcco

Joined Feb 22, 2017
3
Thank you for the reply. I attached the pdf to this reply.
I already made the circuit in the .jpg from the original post but also found the much more simpler circuit in the attdriver.pdf attachment which I might try later.

I'm basically trying to figure out why the transducer I have isn't working with the .jpg circuit I made? I'm just trying to find a circuit to make this transducer work.

Thanks for your help.
 

Attachments

Thread Starter

cbrcco

Joined Feb 22, 2017
3
Unfortunately I don't have an oscilloscope. I am a mechanical engineer that doesn't really have a need for one until this one circuit lol Nor do I have experience in Psice or similar program to simulate the circuit. So any insight you can provide would be appreciated.
 

wayneh

Joined Sep 9, 2010
16,390
Unfortunately I don't have an oscilloscope.
That makes it tough.

One place to start would be to look at the voltages on the base pins of both transistors. They both need to be conducting for the circuit to work. Q1 needs to be fully turned on (I think), so it's base voltage should be at least 0.7V and I would expect even more because there needs to be a bias at Q2. So the Q1 base needs to be 3 diode drops above ground, or ~2.1 minimum. I wouldn't be surprised to the see the full power supply voltage there. Q2 needs to be oscillating on and off so I believe its base voltage will be near 0.7V. These voltages are the values from your meter in DC mode.

Some oscillator expert may come along and give us better value estimates. But in the meanwhile maybe you can collect some voltage data.

A good picture of your build could be helpful also. Another set of eyes may spot something you've missed.
 
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