Of course this is not necessary in this application, as the power consumption of the ESP module is greater by some magnitudes. If not they adjust the drive pulse length automatically ![]() I think this chips measure back EMF to decide if the motor really turned with the right power. They are designed to use just the right amount of power to drive the hands but not waste any energy with overdriving so it gets the maximum battery life. I know of clock driver ICs which do that to compensate for a depleting battery. And a transistor is typical 10 times more expensive than a resistor.īut instead of using a series resistor and wasting some energy in it, you can adjust the length of the driving pulse so that – together with the inductivity of the motor winding – the current reaches exactly the right value. If you use the emitter followers you waste not less energy than with the resistor. ![]() I am not absolutely sure about the ESP, but normally CMOS outputs have protection diodes which serve as freewheeling diodes for this small current. If it is then “open” again you have reached the 12 o’clock position. So it will be activated by the hour hand just before it reaches 12 o clock for at least “5 minutes” (300 impulses on the motor), then as the hour hand leaves it, very soon after that it will be activated by the minute hand for “1 minute” (60 impulses). ![]() with a good position (NOT the 12 o’clock point) you can distinguish this in software.Īssuming the clock mechanism needs second impulses (60 per minute) I think it would be good to set it on the 1 minute before 12″ position. If it is triggered by both hands, then you get a pulse every 3600 pulses from the minute hand and an extra one from the hour hand. I would just add a serial resistor to the motor coil (or use very short pulses) because the ESP works with more than 1,5V).Īnother idea: Use something like an SFH900 reflexive opto coupler for reference detection. The GPIOs of the ESP8266 are stronger than that. +/-4mA at a motor coil resistance of 200 Ohm. the H1344 (first google hit) specifies min. A typical clock chip drives the clock motor with several mA, e.g. Posted in clock hacks Tagged clock, clock movement, ESP8266, ntp, Quartz Post navigation If you’d like to go to the opposite extreme of cost and complexity, how about a DIY retro atomic clock? Or if you’re in need of a wakeup, we’ve seen a ton of alarm clock posts in the past few weeks. Still, even with that small fault, it’s a great build and a great exploit of what can be done with a cheap quarts clock movement. ![]() Instead, the time is just set assuming the clock hands started off at 12:00. says the project needs a bit of work – there is no feedback on the clock to determine the position of the hands. Once the ESP8266 gets the time, it starts hammering the coil in the clock movement until the hands are where they should be. The software for this clock first connects to the WiFi network, then checks an NTP server for the true time. The coils in these quartz movements can be easily controlled by pulsing current through them, and with a few a few transistors and diodes set up in an h-bridge, an ESP8266 is quite good at setting the time on this clock. This clock uses a standard quartz clock mechanism, powered by a single AA cell. The clock chose for this build is an extremely cheap clock pulled right from the shelves of WalMart. decided to experiment with the ESP8266 to turn a cheap analog clock into something that will display network time using a bunch of gears and motors. With a cheap WiFi module and a connection to an NTP server, any clock can become an atomic clock. Even in the face of an Internet of Things grasping for a useful use case, an Internet-connected clock is actually a great idea.
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