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  1. gorgon

    Help with checksums

    I don't think 1280 has much to do with it. The checksum adds up to an 8bit rest of 00. Since the checksum is only 1 byte you can't have a total of more than one byte. I would think that the start value is 00, and then all header and data bytes is subtracted from that and the rest is the...
  2. gorgon

    PIC10F200 and I2C communications?

    How about changing the DAC to a SPI version, since you are using SPI already. If you have hit the memory roof already, you need to revise your selection of PIC variant, or how you use memory. If you program in C, you may save some memory going through the data types in use, and the grouping...
  3. gorgon

    need HELP! with figuring out my LED/Resistor problem!

    If you feed a motor directly from these sockets, you'll have problems when you turn the motor off, or maybe also when it runs. This is due to the induced reverse voltage you'll get from it. Place a reversed diode (like 1n4001) in parallel over the LED and you should protect this from the...
  4. gorgon

    Parallel port relay problem

    Have you tried to use a different monitor? Could be that the monitor is backfeeding some voltage. Will this happen even if the parallel output is turned off when you turn off the PC?
  5. gorgon

    LED ammeter circuit

    You could use the ina139 to monitor the current and then the 3914 to display it.
  6. gorgon

    Inverter Circuit

    Hopefully it is 44 milliohm, not megaohm. To calculate the voltage drop over the IRF, multiply the resistance with the current through it. If you multiply again with the current you will get the power loss in the IRF. If it is activated only half the time, you can divide by 2.
  7. gorgon

    component for Serial data

    What's the distance between the Arduinos? Basically you could add a noninverting buffer after the optocoupler. As long as you only listen, or use the Rx input on the Arduinos you don't need more, if the distance is not too great. If you also want the Arduinos to Tx, you'll need more logic...
  8. gorgon

    need help finding a male terminal block

    Don't think there are room for normal ribbon cable headers on the shown pcb. They all need extra space on the sides(ends). The picture indicates little room at the ends of the blocks, between the green block and the other. TOK ;)
  9. gorgon

    I'm being really dim here

    Another question, the reset vector is set to main()? How do you know that the chip is programmed properly? You have linked the program to release mode?
  10. gorgon

    I'm being really dim here

    I suppose this is stupid, but you do use portc bit0 for the output?
  11. gorgon

    I'm being really dim here

    Are you sure that the 'for' loop is running, why not use 'while' for this?
  12. gorgon

    Help with code (c language)

    You could use a 'switch' / 'case' structure to sort and process on different conditions of the same variable. To separate the key presses, use a 'no-pressed key' condition between keys to reset to an idle condition. You should also add an overall timer to reset any partial counts if no...
  13. gorgon

    New LED light fixture is too bright

    Based on some datasheets 0.5W will give 25-50K + ambient, from 50C to 75C at 25C ambient. It depends on how they are mounted.
  14. gorgon

    Could this circuit work?

    I just wonder where you get the 20uA from in this circuit. What you say is like pulling yourself up with the hair, speaking in a metafor. If I understand you correctly, you say that the photodiode is biased from the 1M over 3V? The bias current can then only be max 3uA, if you drop all the...
  15. gorgon

    Could this circuit work?

    So in effect this virtual 'current generator' is in fact a voltage generator of around 3V in addition to the current in question. A 5mA current through the 100 ohm resistor and the LED will remove 0.5V of the minimal headroom available. I wonder how you manage to get 20uA through a 1M...
  16. gorgon

    New LED light fixture is too bright

    The 22-30W @.7A indicates that the minimum output voltage is 31.5V. The OP should measure the output voltage with a full LED ring, and the voltage dropped over each LED assembly. Replace or shunt each LED assy with a number of 1N400x diodes in series, adding up to a voltage slightly less than...
  17. gorgon

    Could this circuit work?

    You will never get 20uA through there, since the 1M resistor will limit it to 3uA(@3V). (The symbol is also wrong, indicating a voltage generator.) The hFE is typical 270 for this transistor and I can't see that the LED will more than glow if turned on at all, in this design. With a Vf of the...
  18. gorgon

    AM Radio Interference

    If there is a dimmer cicuit on the lights, you may have a HF field generated that blanks out other AM signals. Or just a bad connection in the light circuits.
  19. gorgon

    confusion over LED forward voltage rating

    If you design a mass produced product using this LED, you should design it with a current limiting resistor value that will give you a current not exceeding the max continuous current allowed at the minimun guarantied forward voltage. The max forward voltage will then return the minimum current...
  20. gorgon

    confusion over LED forward voltage rating

    Normally you should have 3 values, min, max and typical.
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