Have you run into any reliability issues in all your versions? Had any relays wear out?
At a cycle per second, I suppose it would take a while, but I'd assume in the long term, the relay(s) switching the flashing dot would be the first to go, since they're switching 60 times for every minute hand switch. If you end up doing another version some time, you could use two relays to switch each flashing dot, SPDT or similar where one input for each relay is high and one is low. Then if you had a pair of LEDs in opposite polarities between the two relays, you could drive each relay half as many times per minute, so long as they are offset in phase by 90 degrees, and get the dot to light whenever one relay is connected to power and one to ground.
Anyways, with the lifetime of a relay and a one cycle per second switching, it may be entirely unnecessary. Neat project with a very satisfying sound!
Yes, I have run into reliability issues with the hand wired designs, and everytime I had the relays in regular IC sockets on the hand wired ones. They often lost contact because the perfboards were quite flexible.
Also, if you look at earlier posts in this thread, you see how much wireing is needed to make one of these work - something has to fail at that point.
with the relays, I purchased used relays from ebay at 0,20€/piece, so I don't know how long they will last - some have failed already, some came unuseable right away. You pay cheap you get cheap.
as for getting the 1Hz signal and the blinking dot:
to get these clocks somewhat accurate, I have to use a crystal and some ICs, they put out a 1Hz signal with 50% duty cycle, the blinking dot is connected to that output through a transistor(so no problems there). But, the counter modules require a duty cycle of 15 to 20% (on time), so there is a circuit with 2 relays converting that.
It works like this:
The first relay is turned on by the output of the ICs, shortly after that, the second relay turns on and breaks the connection between the first relay and the IC. With the other set of contacts of the first relay and a power connection the short pulses for the counter modules are created.
So every seconds 2 relays turn on, which would obviously fail first.
I am not worried about contact failures inside the relays, since they only have to switch about 100- 200mA, which is 5 to 10% of their maximum rating. So either the coils go weak or the mechanical parts fail.
If I find a way to replace this duty cycle converting circuit with something, I might do it - but that would also mean it loses some of the ticking noise. It's what you hear most of the time.
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