wg48temp9
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DIY doppler ultrasound for listening to blood flow.
I curious as to what may be involved in building such a device.
I suspect it would not be too difficult. I found the following project:
http://www.n5dux.com/ham/files/pdf/Doppler-Ultrasound%20Hear...
Ok that needs updating but its not too complicated. There may be an almost one chip solution available these days.
Here is the actual PDF that should remain valid for longer than the link
Attachment: Doppler-Ultrasound Heart Monitor.pdf (691kB)
This file has been downloaded 507 times
[Edited on 11/8/2019 by wg48temp9]
Perhaps a Fetal Doppler Heart Monitor, £13.95 on ebay, could be used or canablized for the transducer.
[Edited on 11/8/2019 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Sulaiman
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I guess that the main problems are getting the two specified piezo crystals and the four transformers.
You could use currently available transducers
e.g. https://www.ebay.co.uk/itm/2-4MHZ-Ultrasonic-Mist-Maker-Atom...
and make tuned amplifiers to match them using toroidal cores and variable trimmer capacitors
e.g. T50-2 https://www.ebay.co.uk/itm/Genuine-Micrometals-USA-Toroid-T5...
but you would have to experiment a little.
missing in the circuit diagrams but present in the pcb artwork are connections from 0v to the transmitter transformer secondaries.
P.S. the 'Ultrasonic Detector Fetal Doppler Prenatal Heart Rate Heartbeat Monitor' on eBay is probably as good as, or maybe better than, the project
circuit.
[Edited on 8-11-2019 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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wg48temp9
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Posts: 784
Registered: 30-12-2018
Location: not so United Kingdom
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5MHz is or was a common IF frequency in FM radios so IF transformes could be used. Its simple to lower the frequency with extra C.
That design was way back when transistors where expensive and you had to design for the maximum possible power gain for each transistor stage.
Now you would use one or two video op amps. I have a TV receiver in a USB dongle. The radio receiver part is probably a single IC and no IF
transformers even ceramic ones that I could see. Mobile phones do some very exotic things to get the signal they want, well exotic for an old ham
radio guy.
I know someone with a baby heart beat monitor she claims no more children so she may be happy to let me have it or borrow it.
The blood sound are fascinating. You can hear the initial rush of blood due to the heart beat followed by a second sound of the back flow from the
elasticity of the arteries. People with hardened arteries get a weak or no second sound. Some very fit people get three sounds. I only have two sounds
both quite loud so my arteries have not hardened very much.
Sorry I could not find a sound file of them.
[Edited on 11/8/2019 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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