book collections email follower instructable user

Hello!

My hobby and passion is to realize physics projects. One of my last work is about ultrasonic sonography. As always I tried to make it as simple as possible with parts you can get on ebay or aliexpress. So let's take a look how far I can go with my simple items...

I was inspired by this a bit more complicated and more expensive project:

https://hackaday.io/project/9281-murgen-open-sourc...

Here are the parts you'll need for my project:

the main parts:

for the transmitter:

  • a step-up-converter for the needed 100V for 5 USD: 100V boost converter
  • a common step-up-converter supplying 12-15V for the 100V-boost-converter for 2 USD: XL6009 boost-converter
  • a LM7805 voltage regulator
  • monoflop-IC 74121
  • mosfet-driver ICL7667
  • IRL620 mosfet: IRL620
  • capacitors with 1nF (1x), 50pF (1x), 0.1µF (1x electrolytic), 47µF (1x electrolytic), 20 µF (1 x electrolytic for 200V), 100 nF (2x MKP for 200V: 100nF 20µF
  • resistors with 3kOhm (0.25W), 10kOhm (0.25W) and 50Ohm (1W)
  • 10 kOhm potentiometer
  • 2 pcs. C5-sockets: 7 USD C5 socket

for the receiver:

  • 3 pcs. AD811 operational amplifie: ebay AD811
  • 1 pcs. LM7171 operational amplifie: ebay LM7171
  • 5 x 1 nF capacitor, 8 x 100nF capacitor
  • 4 x 10 kOhm potentiometer
  • 1 x 100 kOhm potentiometer
  • 0.25W resistors with 68 Ohm, 330 Ohm (2 pcs.), 820 Ohm, 470 Ohm, 1.5 kOhm, 1 kOhm, 100 Ohm
  • 1N4148 diodes (2 pcs.)
  • 3.3V zener diode (1 pcs.)

Step 1: My Transmitter- and Receiver-circuits

Sonography is a very important way in medicine to look inside the body. The principle is simple: A transmitter sends ultra-sonic-pulses. They spread out in the body, are being reflected by inner organs or bones and come back to the receiver.

In my case I use the gauge GM100 for measuring the thickness of paint layers. Though not really intended for looking inside the body i am able to see my bones.

The GM100-transmitter works with a frequency of 5 MHz. Therefore you have to create very short pulses with a length of 100-200 nanoseconds. The 7412-monoflop is able to create such short pulses. These short pulses go to the ICL7667-mosfet-driver, which drives the gate of an IRL620 (attention: the mosfet must be able to handle voltages up to 200V!).

If the gate is switched on, the 100V-100nF-capacitor discharges and a negative pulse of -100V is applied to the transmitter-piezo.

The ultrasonic-echoes, received from the GM100-head are going to a 3-stage amplifier with the fast OPA AD820. After the third step you'll need a precision-rectifier. For this purpose I use an LM7171 operational amplifier.

Pay attention: I got the best results, when I shorten the input of the precision-rectifier with a dupont-wire-loop (? in the circuit). I don't really understand why but you'll have to check it if you try to reconstruct my ultrasonic-scanner.

stoppi71 (author) 5 months ago
I just wonder, why my last three useful instructables about arduino haven't been featured.. It seems that instructables has something against sophisticated technical/physical projects. I should have made a simple ring with my 3D-printer, then it would work with featuring...