SK207 Heterodyne Detector

Schematic Diagram


eagle sch file*.

*Eagle is a layout editor from CADSoft, a freeware version is available (Win & Lin)

Parts List

component  description/value
SG1              Ultrasound transducer (receiver), 40 khz
SPK1             Audio speaker

IC1              CD4069   Hex inverter
IC2              LM386    Audio amplifier

D1, D2           1N4148   High speed small signal diodes

R1                  1 k-ohm      Resistor 1/4 Watt, 5%
R2, R3, R5          1 M-ohm      Resistor 1/4 Watt, 5%
R4                100 k-ohm      Resistor 1/4 Watt, 5%
R6                470 ohm        Resistor 1/4 Watt, 5%
R7, R8            470 k-ohm      Resistor 1/4 Watt, 5%
R9                 10 k-ohm      Resistor 1/4 Watt, 5%
R10                10 ohm        Resistor 1/4 Watt, 5%

VR1              0-10 k-ohm      Variable resistor
VR2             0-200 k-ohm      Variable resistor
C1, C2, C3, C7      0.01  uF     Ceramic capacitor, 25V
C4                 20     pF     Ceramic capacitor, 25V
C5                220     uF     Electrolytic capacitor, 16V
C6, C13             0.04  uF     Ceramic capacitor, 25V
C8, C9              0.022 uF     Mylar capacitor, 50V, +/- 10%
C10, C11          100     pF     Ceramic capacitor, 25V
C12               100     uF     Electrolytic capacitor, 16V
C14                10     uF     Electrolytic capacitor, 16V
C15                47     uF     Electrolytic capacitor, 16V

Ultrasound Receiver

RadioShack ($4.95) no more?
Gibson Tech Ed ($3.19)

A small 40 Khz ultrasound receiver (Velleman / MA40A5R). The bandwith of these piezo-transducers has a narrow peak around 40 khz. A group of students at UNN has measured it.

usound transducer

CD4069 hex inverter

"The CD4069UB consists of six inverter circuits and is manufactured using complementary MOS (CMOS) to achieve wide power supply operating range, low power consumption, high noise immunity, and symmetric controlled rise and fall times."

Fairchild CD4069UBC.
datasheet (pdf)


LM386 audio amplifier

"The LM386 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value up to 200."

National LM386
datasheet (pdf)

Last updated Sat Mar 13 14:59:18 CST 2004