Easier, surely, to use a 555 and a relay?
Timer Switch for wallwart chargers
Jul 30, 2017
28 Replies
A good diy solution is as follows
Most coffee makers (eg cheap as chips
formatting link
) are required to have an energy saving timeout switch to cut off the hotplate after about 40 minutes. This is done with a simple electronic timer based on an oscillator and very long multistage counter which switches off after 2^n cycles. If you use one of these modified to use a timing capacitor of about 10x the value fitted, you will get a timer of around 6 hours (400 minutes instead of 40) Put in a box with a plug and socket and plug the wallwarts into that. There is a push button on the coffee machine with a light to give a push on, push off function if you want to terminate the charging period early.
Not by the time you boxed it up safely etc and certainly more expensive than a ready to go £5 mechanical timer. B-)
You can find a mechanical timer in a nice box for 5 quid?
B-)
Mechanical or electro-mechanical things (relays) have dropped out of fashion in favour of electronics. I suspect the skills and knowledge that produced things like a Creed 444 mechanical teleprinter have been lost.
The server here is ona UPS and shuts down 2 mins after the power goes to conserve the UPS battery for essential stuff. Trouble is it doesn't restart unless it actually loses mains on it's input, so if the power comes back before the UPS shuts down the server stays down. I've amde a solution using a couple of relays, one 5 V, the other mains. Ok the mains one is a modern time delay on type so has electronics to do the delay but I bet there is (was) a purely mechanical solution.
Pulling in against a dashpot and spring to a certain point before the contacts get too close. Then the piston drops out of pot and the pull makes the contacts close quickly. On release the spring opens the contacts quickly, to the dashpot and pulls the piston back in ready for the next on.
And how adjustable is the timer? 25 hours anyone ... or turn off at midnight no matter what time I press the 'Go' button ... (RTC)?
Whilst I'm no programmer even I appreciate how much flexibility you can get using some simple programming and something like an Arduino Nano.
Nothing to do with technology for technologies sake, more like if you want something flexible, programmability is king.
Ask Mr Babbage. ;-)
Cheers, T i m
How about 3 for £6.00:
formatting link
2
or a smaller one but still less than a fiver:
formatting link
Orginal spec is for wall wart chargers. How many devices need > 24hr charge?
A moded mechanical switch runs for the duration of the set "on" period then stops. It has no notion of the time of day.
What *useful* user programable features could one have for a wall wart battery charger timer?
Quite ...
Again, pass, but I was just throwing my 3dth in and an Arduino based solution could do exactly what your electro-mechanical one could do and a lot lot more (thinking outside your specific solution box).
And that's what I like about this group ... the *extra* stuff one learns outside the specific stuff (especially from the right brainers). ;-)
Cheers, T i m
Join the Discussion
Have something to add? Share your thoughts — no account required.
Didn't find your answer?
Ask the community — no account required