8pcs. LED timer PCBs remaining

Discussion in 'Marketplace' started by takao21203, Mar 27, 2013.

Thread Status:
Not open for further replies.
  1. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    This is a microcontroller PCB I made some years ago, I think 2008 or 2009.

    Back then I had high expectations for the dc/dc converter on the PCB, since it is discrete, it is not so much efficienct. But, the PCB works for a week or two from one AA battery.

    Later I did not add parts anymore for the dc/dc.

    It is a LED display PCB + PIC 16f716. Good for timers, counters, temp. display or for experiments.

    Some of these were sold even without controller at all!

    Routing the serial pins for the 7seg. display only takes one solder bridge. Simple 3 wire, but not doing the multiplex refresh on the PCB (without controller).

    I sold these for about $10 and that's below my cost + working for nothing.

    With controller, I think about $15 would be good for the efforts to build them.

    And, I can also ship them with clocks, timers and counters already programmed!

    If there is any question, you are not left alone with a PCB + no information how to make it work.

    Originally 32 pcs. were manufactured, these are the last 8 pcs. remaining.

    And by the way, also there is space for a DS1307 Realtime clock, or a EEPROM. I can also patch the PCBs, adding dc/dc converters. MC34063, MCP1640, or LM2576. All available.

    The original converter is not so much efficient.

    Adding a small dc/dc converter for either single cell or 12V, 30V, etc. can be done at low cost, I have experience with these.

    Would be nice to sell off all remaining PCBs, and it is a useful circuit. At other places, you may have to pay more than double of my price.

    I can either preprogram them with a specific software, or you'd need a FLASH programmer for PICs, and some experience.

    Even having some 7805 here, and yes, there is extra space to add such a thing.
  2. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    Patched the PCB, now including:

    -DS1307 Realtime Clock IC
    -LM2576 DC/DC converter
    -CR2032 Lithium battery for the realtime clock

    -2x LEDs, 2x pushbuttons
    -4 digit LED display
    -PIC 16F716, 12.288 MHz or 8 MHz or 500 KHz

    -Realtime clock software preprogrammed with source code

    All this for only $24.95

    Actually the CR2032 battery holder is placed where originally a discrete dc/dc converter existed on the PCB. So that is now hidden.

    The LM2576 converter is placed where originally a LED bargraph display existed. The driver IC for that is simply not soldered into the PCB.

    6 ICs on the PCB, and a big effort to assemble.

    All brand new parts, and none of the PCB bugs are visible or affect functionality at all.
Thread Status:
Not open for further replies.