Gadget Box

The gadget box is a 5"x3"x2" almunim minibox containing level-converter
and modem intended for use with host time servers supporting the Network
Time Protocol. It includes two circuits. One of them converts a TTL
positive edge into a 26-microsecond pulse at EIA levels and is for use
with a timecode receiver or oscillator including a one-pulse-per-second
output. The other converts the timecode modulation broadcast by Canadian
time/frequency standard station CHU into a 300-bps serial character
stream at EIA levels and is for use with the clk_chu.c or
clk_chu_STREAMS.c modules in the xntp3 distribution.

If only the pulse converter is used, the circuit is powered from the EIA
signal lines and needs no external transformer. The CHU converter
requires an external 12-volt AC transformer or 12-volt DC supply.

The schematic is shown in file gadged.s01 and an assembly drawing in
gadget.s02. Both files are in PostScript and were done using the Schema
schematic-capture program from Omation. Miscellaneous design data, pin
lists and bill of materials are in the ASCII file gadget.lst.

Dave Mills
University of Delaware
6 July 1992
