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  1. C

    Questions on power supply

    "If you want to be "extra careful" with first-time-power-on then start with a series resistor in the 10ohm-1kohm range..." A 10R resistor would be just like a set of old cells and you are "canning" a set of old cells. What you have said is EXACTLY what I have said but you have obviously not...
  2. C

    refresh rate for dot matrix

    Firstly you have break your requirement into a "run-of-8" as this is the maximum number you can scan. So, 32 x 64 becomes 8 x 64 plus 8 x 64 plus 8 x 64 plus 8 x 64 so you are loading 64 bits into the first quarter of the display and 64 bits into the second quarter and 64 bits into the...
  3. C

    refresh rate for dot matrix

    You are talking to a beginner. Why make things complex with interrupt timing when all he needs to do is produce a scan routine. "For a display of 8 lines by 8 columns, each column has 1/100*8 or 1.25ms of display time." This is completely WRONG.
  4. C

    US based PCB manufacturer

    I am just satisfying all those US manufacturers who tell me you cannot trust a Chinese manufacturer to make my boards . . .they only produce RUBBISH.
  5. C

    US based PCB manufacturer

    "Colin, have you used Smiery? Any comments about them? thanks" I have used Smiery 10 times and they are perfect. The only thing is they send you a .pdf and you then send payment by PayPal and this requires them to be at work. This may take an extra day. But http://www.elecrow.com/ is automatic...
  6. C

    US based PCB manufacturer

    The secret to making a PC board is 1. Get a CAD file and "pull it apart." 2. Start with a simple board, and 3. Get someone to help you all along the way. There is a lot of skill in making (designing) a PCB board. That's why you need the simplest CAD program. Many of the sophisticated...
  7. C

    US based PCB manufacturer

    The problem with ExpressPCB and all those "free" program is this: you are tied to one PCB manufacturer. And they charge 10 times more than the Chinese. The US PCB manufacturers say they will make 3 boards for $30.00 But the boards are one inch by one inch. WHO WANTS A BOARD ONE INCH SQUARE...
  8. C

    US based PCB manufacturer

    EasyTrax DOS Freeware version 2.06 - Complete PCB layout package with output support for printers, pen plotters and Gerber. System requirements: PC-compatible; DOS 2.0 or later; 640K RAM; 2Mb of hard disk space. Download (ZIP 485 KB) http://techdocs.altium.com/display/ALEG/Easy+trax...
  9. C

    US based PCB manufacturer

    I get 10 panels made each week 10cm x 10cm doublesided PTH green overlay and HASL for $15.00 plus $10.00 postage I still use the very first PC CAD program ever produced in Tasmania 45 years ago as it has never fallen over and is not frustrating.
  10. C

    Negative Trigger mode on O-scope used for?

    Basically the trigger control allows you to adjust the horizontal position of one waveform on the screen so you can match it up or compare it with another waveform. (dual trace situation)
  11. C

    Alternative Energy.....

    You cannot store 1400 watts. You cannot even store 1 watt.
  12. C

    Alternative Energy.....

    You cannot convert 100 watts x 14 hours to 1400 watts.
  13. C

    Help, transistor circuit not working

    "But you have the transistor connected the wrong way." That's why you have to draw a circuit according to CONVENTION. You cannot expect to see a fault in a circuit if you draw it "up-side-down," "inside-out," "back-to-front" or with crayons.
  14. C

    Questions on power supply

    Many supplies don't provide enough filtering for a pre-amp and the result is a lot of background hum. "Some of us burnt out resistors and other components," That's the very point I am making. You could spend an hour finding the burnt-out transistor(s) in an amplifier - especially a DC coupled...
  15. C

    Questions on power supply

    You should always test a new circuit on a set of old batteries. This way nothing will be damaged. Measure the voltage and current and then you can go to newer batteries and then to a rechargeable battery. Finally you can go to a power supply and see if it works on a power supply. Many...
  16. C

    Faulty Signal Generator

    Do WE get a "Masters Of Electronics" after answering all your test questions. Even after being in electronics for 50 years, I have never heard of a signal generator producing an inaccurate output frequency or switching off and I would have absolutely NO IDEA where to start. That's why you...
  17. C

    refresh rate for dot matrix

    See this article for the principle: http://www.talkingelectronics.com/projects/15x7Display/15x7Display-1.html You don't need any interrupt
  18. C

    refresh rate for dot matrix

    Firstly, it is not a refresh rate, but a scan rate. The only thing you can so is break up the display into 8x 128 and 8x128. But you can already buy modules with this sort of display capability for a few dollars. Why re-invent the wheel?
  19. C

    refresh rate for dot matrix

    If you are driving the display as a "run of 16" you are going to get very poor brightness.
  20. C

    Sound triggered LED project

    You can get 15 outputs from a PIC16F628 is that enough?
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