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  1. foTONICS

    556 clock problem

    ya when i was building am/fm transmitters it was crazy seeing on the scope what an extra loop of wire would do to my signal
  2. foTONICS

    556 clock problem

    you're talking about radio and microwave stuff right?
  3. foTONICS

    556 clock problem

    I took a extremely blurry picture and posted it on the first page. I used an iPod as I don't have a camera so if I zoomed out to capture the entire schematic you wouldn't be able to see a thing. The setup is exactly the same for the other side of the 556 just with different values to obtain the...
  4. foTONICS

    556 clock problem

    I replaced the two 4.7k resistors and the cap and now the 10kHz pulse works, but now the 1Hz is gone side note, is it okay to replace SMD components with equivelant thru hole components?
  5. foTONICS

    556 clock problem

    I also want to mention that I work at a school. There are about 50 other boards with this same setup and they all work so I've narrowed it down to a defective component, I just don't know which one
  6. foTONICS

    556 clock problem

    The supply is a steady 5V fed in from a fixed power supply. I'm measuring the output with a tektronics oscilloscope and a 1:1 probe
  7. foTONICS

    556 clock problem

    When I said supply pin 1 with 2.5V I was referring to the discharge A pin not the power supply for the entire chip. pin 1 is getting it's voltage from in between the two 4.7k resistors. So in theory it should be 2.5V pin 1 is receiving right?
  8. foTONICS

    "wireless data transmission in the terahertz band"

    Well 10m coverage may be useful in coffee shops and internet cafe's. Maybe with a combination of microcells they could help spread wifi through the streets. What caught my eye was them mentioning that it's not as damaging as x-rays, well how much less are they talking about? People are already...
  9. foTONICS

    556 clock problem

    This is not a circuit I am building but one I'm repairing. The voltage divider was just to supply pin 1 with 2.5V from a supply of 5V. The pic is a little fuzzy but the two resistors on the left are 4.7k ohms and the cap is a 0.01uF. The pins , clock wise starting from the top left, are 1; 6...
  10. foTONICS

    556 clock problem

    I have a 556 timer set up to produce two different square waves (1Hz and 10kHz). The 1Hz signal coming off of pin 9 works correctly, but the 10kHz coming off of pin 5 just shows a steady 5V. I checked the voltage divider going into pin 1 (which controls the 10kHz) and it shows 5V. The...
  11. foTONICS

    6264 RAM IC

    ya you were right. Today I asked him about it and he showed me having both chip enables tied together to a switch but having one inverter going to only one of the IC's. This worked as turning the switch HIGH enabled one IC and turning it LOW enabled the other. Also the parallel A0->A0 etc, etc...
  12. foTONICS

    6264 RAM IC

    Hey all, my teacher gave us this problem of needing a 16k x 8 bit memory. He gave us an example of one 6264 and how to set it up but now he wants us to add a second one so that we can get the required 16k. I know how all the enable, read/write functions work and also how the data inputs are...
  13. foTONICS

    lightning arrester @ base station

    Hello all, We were having a discussion about lightning arresters at radio towers and their purpose (providing lightning a easier path to ground so as to not destroy the sensitive Rx). But someone brought up a good point, what stops the wanted RF signal from being shorted to ground? He...
  14. foTONICS

    DC electric motors

    They don't wind DC motors differently than AC ones do they? I'm trying to remember my electric machines course
  15. foTONICS

    Need help in LED lighting

    put the LED under a loop and look for a small brown/black spot on the diode in the centre of the LED
  16. foTONICS

    Need help in LED lighting

    +1 KJ6EAD
  17. foTONICS

    Subaru dash clock problems - pictures...

    did you clean and flux the joints before re-soldering, if not could this lead to failure in the future?
  18. foTONICS

    1200 Baud Modem

    What if you used some sort of low/high pass filter to activate inputs whose outputs manipulated NPN/PNP transistors?
  19. foTONICS

    PLC simulator

    I've been searching for a useful PLC simulator so I can sketch programs at home when I'm away from school. I've tried going to Siemens and downloading their version off their site but it doesnt seem to be compatible with Vista. Does anyone know of an easy to install basic PLC simulator program...
  20. foTONICS

    Is this the 'Tip & Ring' of the telephone system?

    Hey all, I am currently a student in telecommunications. I was painting my room and hence removed all the cover plates. One of them was a telephone jack and inside it there was a red, green, yellow, and black. I'm pretty sure the red is the -48VDC and the green is ground. What are the yellow...
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