I've obtained a vane/flip clock which has 4 digits, but the controller is long gone. I plan to control the clock using a Raspberry Pi and the usual relay boards you get for them - I've done something similar before and know this works.
However, given the relays would have to operate every minute, I doubt they'd last long before needing replacing. I'm therefore seeking a way of running the clock in the same way but without relays. Does anyone have any ideas?
There's more info below on how the relay solution works.
On each digit, each segment has Common (C), Reset (R) and Display (D) connections. On each digit, the segment Commons are connected together to form a digit Common.
So to display a segment, you'd apply +12V to the digit Common and -12V to the segment's Display terminal. To reset it, the -12V would go to the Reset terminal instead.
There are four digits on the clock, and the segments of each are connected together so the R of Segment A on the first digit connects to the R of Segment A on the second digit, etc. The R of Segment B connects to the R of Segment B on the second digit and so on. The same applies to the D connections.
There are therefore fourteen relays for the segments (7 for displaying + 7 for resetting).
Each digit has its own relay for the digit Common (so there are 4 digit Common relays).
So to display '0123' on the four digits, you'd do this:
- Activate digit Common relay for the fourth digit
- Set the segment display/reset relays appropriately to display a '3'
- Deactivate the segment display/reset relays
- Deactivate digit Common relay for the fourth digit
- Activate digit Common relay for the third digit
- Set the segment display/reset relays appropriately to display a '2'
- Deactivate the segment display/reset relays
- Deactivate digit Common relay for the third digit
- (Then do similar for the first two digits)
Each segment needs 280mA to operate, so the maximum current draw at any one time would be 1,960mA (280mA x 7)