Yes! The kit is complete and it works! ( photo 1 )
I wired up the pcb to the battery contacts, speaker, power-on LED. I left off the sensor at this stage
I first fitted the VFO IC ( TL071 op-amp ) and checked that it oscillates and hooked up the output to my scope and determined the frequency range. It goes from 20.8kHz to 147kHz and the waveform is triangular.
Next are the audio amp and the mixer ICs. I temporarily connected a signal generator to the input via a co-ax microphone lead and inputted ultrasound frequencies to it, it was very sensitive and I suspected I was hearing clipping so I decided to secure the sensor.
The instructions stated, "..take care to fit the microphone board so that the microphone is central in it's hole and does not touch the case." Obviously to avoid the sensor picking up handling noise! Because the sensor is secured to the case with 2 layers of sticky sided foam, I needed to get it right first time so I wrapped the sensor with a strip of scrap paper and pushed the lot through the hole, the paper acting as spacer ( photo 2 )
It was easy to assemble the whole case apart from a small mistake on my part. I covered the back of the speaker with a piece of 30 thou thick plasticard to prevent the solder joints touching the speaker but the clearance inside the case is so tight that it wasn't possible to get the rear half of the case on! I sanded the plasticard down and the case fits! Should have used 10 thou plasticard!
The battery holding foam block was stuck in and the unit powered up from a PP3 battery, the foam holds the battery and prevents rattling though the battery lid is rather fiddly.
Testing...
Rubbing dry finger tips together got a response, so does rattling keys. Key rattling probably produces broadband ultrasound so I tuned the VFO across the band and noticed that the peak sensitivity is at 40kHz which is what I expected for that type. I also pointed it at a CRT television set and computer monitor and could "hear" the line coils!
I was concerned that the unit would pick up the 60kHz MSF atomic clock radio signal but I did not hear any emf pick-up at that frequency.
To check the range, my father operated a ultrasound distance measurer whilst I moved backwards and the detector was able to detect the measurer at a range of at least 30 metres at 40kHz and was able to pick up 20 metres when set to 100kHz! A pretty good range for something inexpensive!
It is nearly 9pm BST at the time of typing and it's getting dark soon, so hopefully a bat will fly about within the hour.....
My conclusion, it's a nice easy project to put together but then I have a lot of experience of soldering and electronic assembly. The pcb mounting was the only real problem with this but I was able to overcome it with some thought. I might get one for myself or I'll design a better one using a sensor with a broader frequency response - most probably a condensor microphone.
Overall THUMBS UP!