40 and 25 kHz Transmit Piezo Transducers
The following parts are provided for your convenience in prototyping and exploring ultrasound.
40 AND 25 kHz Receive Piezo Transducers
This Kobitone receiver PZT, #400SR16, is ideal for experimentation, and is used in our ULTRA-RX1 Receiver Kit and ULTRA RX TEST JIG1 Kit. It has a diameter of 0.65 and a depth of 0.50 inches. The two pins are spaced 0.4 inches apart and have a diameter of 40 mils. The center frequency of received pressure is 40.0 kHz +/- 1.0 kHz. Sensitivity - the voltage received at the center frequency - is specified to be -65 dB relative to 1V per ubar. Bandwidth is specified as -6dB at +/- 2.5 kHz. See our article "40 kHz Piezo Transducers," which describes typical values for PZT parameters.
This Fastron ferrite choke, #07MFG-682X-50, has an inductance of 6.8 mH and is useful in broad-banding the response of some 40 kHz PZTs. It has two 0.025 inch diameter radial leads spaced at 0.150 inches and has a body diameter and height of 0.35 and 0.46 inches.
High GBP 8-Dip OP-AMP
The high gain bandwidth product (GBP) OP-AMP, NJM4580DD, is ideal for 40 kHz work. While transistors can be used in circuits at 40 kHz, it is often useful to use op-amps, i.e. for making synthetic inductors. Typical audio op-amps don't have an adequate GBP for 40 kHz circuits; and, we suggest op-amps with a GBP of at least 10 MHz. The JRC4580DD in an 8-DIP package meets this need.
Pin assignments are the same as the generic 8-DIP dual op-amp IC: Pin 1 = U1 out; Pin 2 = "-" U1 input; Pin 3 = "+" U1 input; Pin 4 = Minus Supply or ground (for single-supply operation); Pin 5 = "+" U2 input; Pin 6 = "-" U2 input; Pin 7 = U2 out; Pin 8 = VCC (+ supply).
40 kHz Capable Ferrite Toroid: FT-87A-J
Ferrite toroids are often used as a form for winding a coil or broadband transformer, enabling a large inductance or xfmr in a small space. The FT-87A-J is suitable for 20 kHz to 1 MHz electronic circuits, corresponding to ultrasonic work. For a desired inductance, the number of turns required is calculated as follows: For the FT-87A-J, N (# turns) = 1000*SQRT(L(in mH)/6040). Hence 18 turns provides for an L of 2 mH. The equation varies for different sizes and types of ferrite materials. The core has the following dimensions in inches: OD, 0.870; ID 0.540, and height, 0.500.