Schematic design and PCB layout can be found on EasyEDA.
The DCF antenna doesn't work well when it's in proximity to EM-noise sources. Possible noise source are the rest of the electronics of the clock or a laptop. The solution is to put the DCF-antenna and the decoder in a separate housing. It might not be necessary to use the separate housing once the clock is properly designed instead of using the breadboard and flying wires.
Steps to follow:
- Using the Hammond 1593NBK.
- Converting the DWG file to DXF using CloudConvert.
- Cleaning up DXF using LibreCAD
- importing in EasyEDA.
- DCF antenna : HKW AFET 77.5 - 10x100/70
- DCF decoder : HKW EM6 DCF 3V
- Output drive capability is only 30µA!
It should be easy for the customer to find a suitable cable assembly to connect the box. The connector should also be small and low profile.
- Stereo audio jack cable :
- flexible, cheap, readily available
- user might be tempted to connect headphones. This must be avoided. At the least, the headphones shouldn't be damaged.
Modular jack cables:
- 4pins, 6pins, 8pins, common use in POTS telephony and ethernet.
- Ethernet cables are not that flexible.
- Big connector. Might not fit inside the housing
The initial idea was to mount a TRRS audio headset socket directly on the PCB, Doing this would make it hard to correctly drill the needed hole in the front panel. Moreover, such a connector, which needs to be placed against the wall of the housing would require a longer PCB than stated in the datasheet of the box.
Two JST XH connectors will be used instead. One connects to a panel mount TRRS audio headset socket. The other connects to a panel mount LED.
Many audio cables are constructed as two pairs of two wires. So the left and right channel each have their ground wire in close proximity. The ground wire is connected to the sleeve. To take advantage of that cable configuration, the GND signal is here also connected to the sleeve.
|JST XH||Signal||Audio jack|