I am trying to build one ultrasonic mist IOT device for this github project. SO in the power supply part it needs to have almost 70V input voltage, so for more Voltage you can use boost converter series connections like this (USB 5VDC / Two series 35VDC by MC34063 DC/Dc Converter):

enter image description here

Also one try to build the schematic part of power supply:

enter image description here

So i like to know does this kind of schematic is correct and have your suggestion for making it better.


Based of the comments and .. this kind of connections seems dont working. but it could be done by the 555 IC to boost from 5vDC/100V similar to this schematic in this Video( dont find it calculation!) : enter image description here that i found the duty cycle and frequency calculation for IC555 for frequncy&Dutycycle (example 200khz and 90%DutyCylce) here as you can see:

enter image description here

and the output signal could be given to this circuit as you can see ( from here): enter image description here But this schematic is poor and betters to have feedback to 555 as shown in the described you tube links circuit.

ALso i possible like to know about other alternative circuits.


  • 2
    \$\begingroup\$ Your supplies are non-isolated, so as soon as you try to connect the "upper" one to the "lower" one, you'll short the "lower" one's output to ground and Bad Things will happen. You need to make one supply that boosts from 5V to 70V, or you need to make or buy isolated converters. \$\endgroup\$ – TimWescott Oct 17 '20 at 16:48
  • \$\begingroup\$ I was not sure about isolated ... but by seeing this video i get it, so i guess the answer of this question is no but i asked : do you know any isolating elements for this purpose (expect the Trans)? \$\endgroup\$ – el-ss Oct 17 '20 at 18:44

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