Hi Elektor fans. I finished my alternative software for the Nixie Clock kit. It is necessary to change the supplied toggle switch to a push button, in order to access and change the configuration parameters.  Other modifications are optional but usefule I think... The software adds: - date diplay (EU or USA format)  (USA format only unless PCB is modified) -EU or USA DST correction -Anti poison display -Alarm clock function -WS2812 type LED backlight control -night time dimming of the backlight It is ready to handle the next GPS Epoch if needed next year. Have a look at the youtube clip first to see if it would be suitable for you... The documents should help to program your clock, but read out the exisiting program first so you can roll back if you don't like it! (Usual disclaimer of course:  I don't take responsibility for any damage caused by using my instructions or software.) Andy

Referenzen : (1) https://www.dega-akustik.de/fachausschuesse/ma/dokumente/vibro-psychoakustik/ (2) Elektrogitarren - Technik und Sound, Helmuth Lemme, Elektor Verlag 2003 (3) Cadfaels – Passive Schaltungen für E-Bässe, http://www.ak-line.com/medium/Bassschaltungen.pdf (4) „300 Schaltungen“ Schaltung 18  

Thanks Nick for your input. I've done my best to rule out mistakes on my part. I have double and triple checked placement of all parts. My solder joints are good. I set up a piezo speaker and a signal generator to produce an ultrasonic audio signal and then I traced the signal through every part of the circuit with an oscilloscope. Everything seems to be functioning as designed from front end to back end. But the sensitivity is miserable. I have two other bat detector kits that I've built that perform far better then this kit. When I set them up at dusk, the sky is just chattering with bat noises near and far and I have to turn down the volume just to keep my ears from hurting when a bat flys overhead. But with this kit, occasionaly I'll get some scratchy sounds with a close flyby. I guess it's just a bad design. What a dissapointement. Money wasted. 

I've built two of the kits - they're both deaf by comparison with my old magenta kit ... I built 2 because the first kit was incomplete and I left it - bought another and got it going, then built a second to see if it was any better - it wasn't. Nick

I have completed the kit. Everything seems to be functioning. I am able to get a signal and speaker output from the local bat population but the sensitivity is just horrible. Only the closest bats are picked up and the sound is scratchy and poor. Measured voltages are correct. I've tried adjusting the sensitivity and hysteresis to optimal settings. I've tried the various DIP switch options. And yet the performance is just abysmal! I thought that this kit with its sensitive mems microphone and unique method of detection would be an vast improvement over my other unit which uses a simple electret micophone and scanning heterodyne detection. But it turns out that my old detector performs very much better and with greater sensitivty and resolution than this kit does. I'm going to start trouble shooting by following the signal with an oscilloscope as it goes through the unit but I don't know if I'll be able to determine the reason for such poor performance. Is it possible that the Mems microphone is damaged or in some way defective? Did I damage the SMD while soldering it to the board? All of the component seem properly placed. I'm very dissapointed with how this has all worked out. If anyone has any ideas please let me know.