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  1. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    I see what you mean. There was a fault in my original row selection. Here it is modified and corrected , with the output at the collectors and a single resistor, that was actually my intended idea for activating only a single row of LEDs and sensors at a time.
  2. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    My circuit already has "open collector row selects". Did you mean "Column selects"? Even so , It will not "take all of the sensors not activated out of the circuit" The Row or column selected will activate all sensors in it. To select a single element in the matrix you would need a "selector"...
  3. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Bob, I don't oppose it,I do think it is not needed. It increases the devices needed for an NxN matrix to N^2 instead of the order of N. That is a big disadvantage.
  4. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    The fact that the room is dark or not has no effect. The sensor has a "Daylight blocking filter",(this "coating" is a must in that type of device,otherwise a single "isolated" device will not work properly anyways). That means only IR light passes through to it. see the TCRT5000 datasheet.
  5. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Bob , the ULN2803 driver is an "open collector" device,effectively a tri-state driver. i.e. when row is selected(in="1",out="0") when row is de-selected(in="0",out=tri-stste) only one row selected at a time. Thus R2=R/19 is not present.
  6. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    It is a good idea to make it modular. Modularity here lends itself to powers of 2 I would use an 8x8=64 as a basic building block. To use a block requires: For the rows drive => one 8bit shift register + one 8bit driver =2 ICs. For the columns mux tree => one 8bit analog mux = 1 IC. A total...
  7. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    It absolutely does, look at post #18 combined with #27.
  8. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    A single ULN2803 is an 8 bit driver,you can drive 8 rows with one device. for 20 rows 3 ULN2803s are needed. No need for circuit protection. Capacitors may be added on the 5v to GND line. Say a 22uF/10V tantalum + a 0.1uF ceramic one at each Row, but it is not absolutely needed. I would try...
  9. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Bob, What you are suggesting is the brute force way. It isn't the way to go...
  10. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Look at post #18 it explains how to read the columns with MUXs . You need 5 control bits to select from the 20 columns (can be done with a shift register or directly). For the 8 --> 1 you can use the CD4051B or similar. For the 4 --> 1 you can use the CD4053B or similar.
  11. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    1. Is it is possible to light all LEDs at once,but I explained why you shouldn't do that (too much current). 2. The answer to the identification of the IR LED and sensor is found in the TCR5000 data sheet, In general,you should never use any device without reading and understanding it's...
  12. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Steve, It looks like you did read post #18,but it hasn't quit "sank in". I think it would be the way to go and recommend you re-read it. A breif explanation: Assuming each Led is driven by 10mA . Driving all 400 LEDs all the time will require 400x0.01A=4A which is a waste of energy and a...
  13. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    As I said before ,the way to go is with a matrix. Row activation and Column read ,or vis versa . The basic is a square NxN matrix such that N^2 >400,thus N=>20. In general , it can be done with an NxM matrix ,such that N is not equal to M. Since commercial Analog multiplexers come in powers of...
  14. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    Steve, What voltage and current are you planning to operate each sensor(actually the diode)? Are you looking at 5V/10ma ? other values?
  15. dorke

    Cheapest way to get data from multiple(100s) of sensors?

    If what you actually need to get from the sensor is "digital information" only, i.e. Is it sensing "proximity" or not. Then the way to go cheap is like a "PC keyboard" implementation. That is an I/O expander(matrix type,actually only input expander) with a serial interface. The serial...
  16. dorke

    new app

    I tried it. It is agonizingly slow.
  17. dorke

    Amp keeps going into protection mode

    You are welcome. Good luck with the other amp. If you would need help with it ,we are here.
  18. dorke

    Amp keeps going into protection mode

    It should be protected against output over current(or short). That should happen by the amp going into protection without any fuse blowing.
  19. dorke

    Amp keeps going into protection mode

    I agree with you on both the diodes and the capacitors. The fact that you have the voltage change with the music/bass/treble suggest the caps aren't filtering well the AC. The transistor Q2 is fine. As it is,I think you could operate the amp. with the wire cut as we did before. Inserting...
  20. dorke

    Amp keeps going into protection mode

    About the Transistor "diode test". Put the "Red probe" on the Base and check with the "Black one " (without moving the Red) once to the Collector and Once to the Emitter,what do you get? About the effect of the music that plays on the reading on R3: With Q2 and D11 disconnected. Get the volume...
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