Search results

Search Forums New Posts
  1. BobK

    notch rf filter

    Are you sure you do not mean 1470 KHz, that would be in the AM broadcast band. Bob
  2. BobK

    Battery used up

    http://www.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_US_CT.pdf Bob
  3. BobK

    Another Joule Thief Thread

    I looked at my breadboarded Joule Thief again, and I was wrong before when I said the duty cycle was really low. I now remember that that was on simultion that I was seeing that. On the actual circuit with a 1.2V battery running a 3.3V LED the duty cycle looked like about 15%. This would...
  4. BobK

    ethernet to serial conversion

    I have never heard of mg (millgrams) as an electrical unit before... Bob Edit: I see you changed mg to Mb, that is a little better. Mb/sec is what I now think you mean.
  5. BobK

    How can I drop 12V to about 8.4V?

    What is the current rating of the motor? If it is not marked, use an ammeter to determine how much current it draws from your 8.4V battery. Bob
  6. BobK

    Building a digital clock

    Well, you do have to deal with other things, like being able to read a datasheet, setting up configuration registers, and how many PC programmers have ever written an interrupt handler? So, it is different in details, but the overlap (programming logic) is large and the same. Bob
  7. BobK

    Loading a blinker relay.

    A light bulb? Bob
  8. BobK

    Building a digital clock

    It is not completely different. You will not find c# on a micro. C, assembler and basic are the most commonly used languages. Bob
  9. BobK

    Electrolyte Testing for Homemade Batteries

    Um, I wouldn't recommend anything suggested on that web site... bob
  10. BobK

    Electrolyte Testing for Homemade Batteries

    KJEAD, Did you read the paper you linked to? Then down the page a little they show an LED circuit with a 3V battery and 1 1MOhm resistor! Bob
  11. BobK

    Electrolyte Testing for Homemade Batteries

    Keep the bleach away from the ammonia! Bob
  12. BobK

    People 'trading' their hardware hacks?

    Give an example of the kind of thing you think you could sell in small quantities at a profit. Bob
  13. BobK

    Another Joule Thief Thread

    I have built a "standard" Joule Thief, and looked at the waveforms on the scope. The duty cycle is extremely low, I would estimate a few percent from memory, so you are not getting that much light out of the LED. The efficiency is high because there is no resistor in the circuit, so most of the...
  14. BobK

    Transformer Question

    The coil has an inductance that limits the AC current going through it just as resistance limits the DC current. But the current in an inductor is out of phase with the voltage, which means the product of the two is 0 (when averaged over a cycle) and no power is used. So the only power used...
  15. BobK

    RS-232 PIC Communication

    I am not sure whether your call to OpenUart will do everything you need. I have always set up the registers myself, I find it less frustrating that trying to get a library function to do what I want. Bob
  16. BobK

    RS-232 PIC Communication

    Well, if your delays added up to 1M instructions and it is blinking at 1Hz, the clock frequency is 4MHz, because it takes 4 clocks to execute 1 instruction. Looking at your code, you have enabled the 4X PLL in OSCTUNE, which is why your cloock is running at 4MHz. Bob
  17. BobK

    RS-232 PIC Communication

    1. The baud clock is based on the clock frequency of your PIC, not the instruction cycle. If the instruction cycle is 1MHz the clock frequency is 4MHz because it takes 4 clocks to execute and instruction. 2. You DO need to understand the configuration bits and set them correctly to use the...
  18. BobK

    Automated Lead Acid Battery Capacity Tester

    It is hard to help you if you won't tell us what range of current you need. Bob
  19. BobK

    Increase in voltage, indicator lights stay the same

    You can use a single resistor, but you need to know the current that that the indicator draws at 12V. Once you know this, calculate the resistor that will drop 12V at that current (24-12), by Ohms low: V = I R R = V / I For example, if the indicator is using 50ma (0.05A) then the...
  20. BobK

    Automated Lead Acid Battery Capacity Tester

    What is the range of currents you require? An LM317 can make a good constant current source of up to 1 A with a range of 10.5 to 12.6 Volts input. But I suspect you are talking about higher currents than that, no? Adding external pass transistors can up the current output. Bob
Top