Mechanically Scanned Clock

Bob Blick's "Propeller" Clock

The enclosure is done! pc1201.jpg (64245 bytes)
(Click on the image for a bigger view)

More pictures:
 Here's what it looks like w/o the strobe...

 "printf" feature for debugging spinning hardware! 

Artie Schleifer contributed the woodwork and the machining to modify the DC motor.
Motor modification details

backside.jpg (37140 bytes)    Back side of clock.

rotorback.jpg (37997 bytes)    Back side of propeller.


My version (3) of Bob's clock is designed to be turned on to display the time on demand.
To do this, I need a way of keeping time when the propeller isn't spinning.
A 3V lithium watch battery is used to run the real time clock on a Rabbit 2000 core
module running eForth (see Rabbit Forth). Now running gForth. Note that the Propeller Clock uses RCM2300 serial port A to talk to the display and serial port C for control commands.

When the propeller starts, the display processor (a PIC16F873 on the back side of the
propeller) receives the current time from the Rabbit via a RF link.
The display processor then keeps track of the time based on its 16.0 MHz crystal for the duration of the run.


If you are interested, you can read about some of the technical problems and their solutions in Propeller Clock Design, and design calculations for the DC-DC converter.


The clock must be balanced.


Control and Communication.


The display modes presently supported include:
Standard digital clock (12 or 24 hour format)
L-mode (1 Hz display of all digits in the same position)
Message window (12 characters in 180 degrees)
printf (displays the contents of any data address at positions 0,1)
A-mode (2 Hz serious jitter)

The display modes to be completed:
Analog hands

Version 3 files:

Display Processor Schematic
Wiring harness to LED Drawing
Display Processor source code (PIC16F873) pclk3_r5.asm 

Control Processor Schematic 
Control Processor source code (gForth for Rabbit2000) rabbit_PCLK3.fs 

Python code to communicate with the Control Processor via Bluetooth to display the date and module to convert strings to display index


Forth code for the CP LED & switch rabbit_io.txt

How to make an In-System Programming cable

Power Supply Schematic
Power supply pinouts: LM317, LM340-5, LM2941
How to skywire the power supply


More clocks: Nixie

Previous versions

rev2_pic1.jpg (29827 bytes)
Version 2

rev1a_pic1.jpg (21547 bytes)
Version 1

| © 2005, 2009 Ken Staton