Cambridge Kits
Time wrong ?
MSF CLOCK
is
EXACT
 msfclock.gif
Never gains or loses, SELF SETTING at switch-on, 8 digits show Date, Hours, Minutes and Seconds, 0.5" and 0.3" red LEDs, larger digit Hours and Minutes for easy "quick glance" time, 24 hour format, automatic GMT/BST and leap year - and leap seconds, expandable to Years, Months, Weekday and Milliseconds or use as a stopclock to show event time, also parallel BCD (including Weekday) output for computer or alarm and audio to record and show time on playback, precise minute and seconds pulses, uses 4000 series CMOS so no microprocessor interference, receives Rugby (callsign MSF - "standard frequency") 60 kHz atomic time signals accurate to 1 part in 10^13 (300µs in 100 years), built-in antenna, 1000 km range (provision for external antenna beyond), narrowband (100 Hz) superhet receiver, 50dB agc range, can drive "S" meter, 3 kHz (audio) IF, receiver board (antenna, serial data output, 10 mA supply) can be remoted (3 wires), serial data output 8 V = carrier, 2 V = break, Seconds, Minutes and BCD outputs 0 - 10 V, Weekday as Wednesday = 3 etc, connections by terminal block, polarity protected, needs 12 V at 150 mA, 5 x 8 x 15 cm, 400 g.

"complete and well documented", Radio and Electronic Constructor.
"particularly satisfied with the pcbs", BIL in Rochdale.
"neat looking", CMT in Malta.
"interference immunity higher than other makes", RAF in Sussex.
"worked first time ... superb kit", MDA in Luton.
"very good signal", RWD in Saudi Arabia.
"well made, very interesting", PC in Eire.
This fun-to-build kit includes all parts* as well as detailed assembly and operating instructions, all decoding details and needs only a meter and speaker to tune.
The kit includes a ready-cut piece of copper laminate and full size foil pattern for easy drawing, etching and drilling of the RF board. The RF board is 146 mm long, single sided with wide tracks and generous spacings as shown here
and the kit includes ordering details for etch resist pen and ferric chloride.
The other 3, more intricate, digital boards in the MSF Clock are ready etched and drilled.

* The receiver board needs
  • a 3.5mH inductor for L2, Toko part number CAN1A350EK which sales@modecomponents.co.uk can supply,
  • 2 dual gate mosfets such as 3SK85, 40673, 3N201 or BF988A (Farnell stock number 663-712).


If someone wants to offer a PCB (drilled or undrilled) for the RF board of this kit, then their contact details can be announced here.
BST to GMT Converter
BST to GMT (or any other time zone) converter circuit in Wireless World, 1981 Aug, page 56.
 
Analogue Display of MSF Time
Use the Seconds and Minutes outputs of the MSF Clock to drive analogue stepper clocks from the MSF Clock's internal 11 V supply as follows.
SYNCHRONOME needing 2 pulses/minute - adjust the potentiometerfor 2 pulses on the minute.
 60circ2.gif
SYNCHRONOME with 3000 ohm coil needing alternate polarity 24 V each minute (just works with 11 V)
 60circ3.gif
Domestic QUARTZ movement, 1.5 V battery driven, 60 ohm coil needing 1 pulse each second.
 60circ4.gif
Telephone Answering
Find the date and time of every telephone call you receive. Record the 3 kHz audio output of the MSF Clock with the message, then play it back through the MSF Clock to see the Date and Time. Play back through a Tunable Audio Notch Filter set to 3 kHz to hear the message.
 
Stopclock
Find the date and time that an event occurred. Change the connection between "Data 1" on the RF board and "Data 1" on the Logic board to the diode gate consisting of the 2 diodes and 18k and 82k resistors shown for displaying Milliseconds. Use the event to connect 11V to the junction of the diode and the 82k resistor to freeze the display.