I've bought a cheap Chinese LED clock. I'd like to hack the device so I can make it a counter that can be updated via a button (and eventually via MQTT)
Is this feasible?
If not... I'll use this as a clock.
I've bought a cheap Chinese LED clock. I'd like to hack the device so I can make it a counter that can be updated via a button (and eventually via MQTT)
Is this feasible?
If you remove the chip, the display can certainly be used.
It should not be difficult to reverse engineer the PCB and determine the display connections. Some multimeters, when used on the "continuity" setting, will cause an LED to light up weakly. The polarity of the leads has to be correct.
In reality I say no. Sucha a project needs lots of experience and experienced people would not go for it. They would buy well documented circuitry.
Reverse engineering is very difficult.
It is a multiplexed 7 segment display. You can clearly see the following:
The 7 x 100R resistors are connected to 7 consecutive pins on the IC - they will be the current limiting resistors for each of the 7 segments.
The 4 x 2k resistors are base resistors for the 4 x 2SC8550 (or equivalent) pnp digit driver transistors.
There is a tutorial showing how to multiplex 7 segment common anode LED displays here.
Their schematic shows all the components that i identified in post #5.
use it as clock.
Get an Arduino UNO/NANO and a 4 digit display with a driver IC (search for MAX7219, HT16K33 or TM1637 with 4 digits) write a short program and you are ready.
is pretty handy! If the chip is a PIC, it can easily be reprogrammed. Get a PIC programmer, download MPLAB and away you go. Otherwise, remove it and use the port pin pads to access the display.
Hi,
Also show the other side of the board.
Ah, so those are the ‘segments’.
Thank you all for the advice... I dont want to use the shitty looking 4 character 7 segment digit boards... they look so "Back to the future". (nothing wrong with BTTF, but it is 40 yrs old. I like the look of this display and its brightness and size will be ideal where I plan to use this counter, and so if you know a similar looking display that could be used, then I maybe swayed.
I think, bypassing the chip and adding my own, will be something I have to look into. I need something reasonably fast to implement. (More due to the fact I dont have much time being a new dad and bloody work takes up most of my week days).
Cheers again everyone who has given input.
Yup... these small LED's work well and are nice and bright. Which will be useful for the counter as I plan to be over 5-10metres away from the counter.
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