Found this AMF LED Lap Timer on Ebay for the princely sum of £12.
It's not quite a stopwatch, as you can only capture lap times while the counter continues in the background. The top button starts the timer, and each time you press it subsequently it reports the current elapsed time. To return the moving counter you press the display button. You can't stop it completely without resetting it.
Still, it's an interesting piece and a tactile delight.[/img]
No idea, they all seem to have a different functions? Using "4" seems to be closest to a normal stopwatch. Start/stop/reset. It's still an enigma for me, no usable info to be found....
The Ruhla stopwatch is based on the Intersil 7045 clock/stopwatch chip. This has a 24 hour clock and four stopwatch modes. The stopwatch modes are;-
1. Standard; Counter starts when start button pressed and stops when pressed a second time (cannot be restarted). Resets when reset button pressed. 2. Sequential; Timer starts when start/stop is pressed and when pressed again display freezes, counter resets to zero and immediately starts counting again. Reset halts and zeroes the count. 3. Split mode; Same as sequential except that each press of the start/stop button freezes the display (a lap time) but counter continues to run in the background. 4. Rally mode; Counter starts when stop/start button is pressed and stops when pressed a second time. Restarts when stop/start is pressed again etc etc. The three operation buttons on the watch are start/stop, display and reset. I doubt the clock option has been enabled on this stopwatch. Pretty sure the Omega SP100 used the same chip as the operation is identical.
What isn't immediately obvious is that this is a true 1/100th second chrono- uses a 6.5536Mhz crystal to derive the timebase so no 1024Hz fudging! Also, along with the Omega, made it usable in Olympic/International events for timing purposes.
Hi old Tom, thank you for that valuable information
About the leds, no idea if they are dot matrix, they seem to look the same like the leds on the pile of vintage HP led calculators I used to have. (sold) I stored the lap timer somewhere.... (removed the batteries) I'll try to find it again :)