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  1. J

    IC 555

    No it is probably best to tie it to a switch so you can actually reset the circuit. But, it is a bad idea to leave them floating. So you would put a resistor in series with the switch from VCC to GND and then connect Pin 4 to the switch/resistor connection. This keeps the pin in either one of...
  2. J

    IC 555

    Why would you leave the reset floating? If pin 4 is an active low pin, then I would tie it to VCC for normal stable operation. Bad idea to leave pins floating that perform a definite function. Maybe it was you touching the circuit that grounded pin 4 and caused your problems.
  3. J

    IC 555

    to add to what I said, current flows when there is a voltage potential between two points. This voltage potential is what we call 'Voltage'. Just realize that no current can flow unless you have a voltage difference between two points. Think of the bird that stands on a 100k volt electric line...
  4. J

    IC 555

    Yes, if you look at the waveform in that diagram it clearly states that the output is HIGH when the capacitor is charging, since your LED is attached to VCC, pin 3 needs to be a LED voltage drop lower (plus a little more for the resistor) then VCC for current to flow and the LED to light. They...
  5. J

    IC 555

    Because no device is perfect. Resistors have a 5% error margin, capacitors have leakage, etc. Also your timing period is very long for a 555. The smaller the timing period the more accurate the 555 will be. Read this page...
  6. J

    I want to test this transformer

    Well first thing I would do is figure out which wires go to each coil and write down the resistances. The reason for this is to see if the coil is center tapped. Normally speaking in a step down transformer, the larger wires are the secondary and the smaller wires go to the primary. From...
  7. J

    Schematic to reality conversion

    You may want to invest in a multimeter. It will make your life ten times easier. Like not having to wait for an answer to a problem that you could have solved with one. :)
  8. J

    IC 555

    I am with Rleo, this thread has only got way more confusing then it ever needed to be. As someone who is starting out you should not be trying to understand the intricacies of an IC circuit. Instead you should just be understanding them enough to put them to use in other simpler circuits. That...
  9. J

    IC 555

    Did you look at the schematic? Trace Pin2 to Q22/Pin3. It should make some sense to yourself by now.
  10. J

    Greetings from Havana

    Good news, all the republican candidates agree with gonzo. You may have everything you need in short due time. :)
  11. J

    Capacitor values for opamp circuit and adjustable gain

    bobk is a sniper in his day job I presume. :D
  12. J

    Capacitor values for opamp circuit and adjustable gain

    Reason for the pot on the output is to act like volume control. I have seen it on the input and output but never in the feedback loop before. Though I can't give you a specific reason for it. I have an opinion on the caps, but I don't want to steer you wrong as I really don't know how it will...
  13. J

    What Devilry Is This??

    I appreciate this site a lot. First and foremost because of the professionalism of the people here. I don't mind the odd joke or poke, but it should come with a little bit of helpfulness to. I wonder what the avg age of people here is. I got it in my head that the avg age is older then I am. :)
  14. J

    What Devilry Is This??

    Before you make a joke you should ask yourself this. How would you like it if someone made a joke when you were frustrated and only wanted a bit of help? Personally I only been offended once by ravin. (even though he meant nothing by it I am sure, but I didn't find anything funny about it) But...
  15. J

    AVR for 3phase generator

    Let's try this one more time, maybe this time you will actually post something useful. What is an AVR?
  16. J

    I/O Expansion Of 16f877a

    Have you thought about shift register? An article about I2C I/O expanders. 9555 and the 9535. Porting the code should not be to difficult. http://www.neufeld.newton.ks.us/electronics/?p=241
  17. J

    how to learn to solder????

    plenty of youtube videos.
  18. J

    Boost converter

    You trying to tell me that the UC3843 is for FET driving just not optimized driving? The datasheet says sry, just a little confused on what exactly is an optimized driver. I guess that FET driver chip you linked to could be used in between any converter IC and a FET to give me the needed drive...
  19. J

    Boost converter

    This is what I come up with. But I have some serious doubts to whether this will work. Vcc = 14 - 16V transformer is 12VAC @ 50A 1. Datasheet says to set Rsense by the graphs, well none of the graphs are even close to the range I will be using. I used the 1R resistor in the schematic on PG 12...
  20. J

    Boost converter

    Thanks bob, I took a quick look on digikey. I found something that has a gate driver, but the specs look to low for what I need. Maybe I am interpreting it wrong? I think this one or the max773 will work for me. I am going through the datasheet now. The max773 datasheet has a schematic for a...
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