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  1. AnalogKid

    What to do with all these chips?

    Basically, it is two sets of time-or-day counters, one for the display and one to hold the alarm value. The outputs of both counter strings drive the two sides of a bunch of magnitude comparators (7485 or equivalent). The A=B output from the comparators drives the alarm device. If a basic...
  2. AnalogKid

    What to do with all these chips?

    Any time-of-day clock project is a good way to suck up lotsa TTL parts. For something different, consider a binary clock. Six columns of LEDs (on/off, red/green, whatever). If in your pile of parts there are two analog meters, another variation is a meter clock: TTL counters > discrete D/A...
  3. AnalogKid

    Circuit with an integrated FLIP FLOP

    Start by making a chart called a truth table with three columns: A and B for the inputs, and C for the output. List all possible combinations of A and B, and the resulting C condition for each one. Many flipflop datasheets have tables like this to summarize operations. ak
  4. AnalogKid

    555 timer

    What is your desired LED current? A bipolar 555 (not CMOS) can source or sink enough current to drive a normal little LED directly, so there is no need to invert the output. Any online 555 calculator will give you component values. If the LED must be driven by pulling the anode up to Vcc...
  5. AnalogKid

    Wind Detecting Circuit

    Not to be confused with a wind bag detector. ak
  6. AnalogKid

    measuring time and distance

    Taking samples based on wheel rotation means the samples are taken at fixed distances along the track. Normally a system like this would collect data at fixed time intervals, but your way will produce similar results. Either way (fixed time interval or fixed distance), there will be an...
  7. AnalogKid

    Sky Boxes.

    Good project cases are always good to have stored away. Photos? ak
  8. AnalogKid

    Sky Boxes.

    I suggest you add more detail to your question. For example: What is a sky box? ak
  9. AnalogKid

    Changing a positive and negative audio signal to positive only

    Note that the battery in the clamp circuit can be just about anything, such as a single AAA cell, coin cell, etc. Even a watch battery (309, 393, whatever) will work, though it won't last very long. ak
  10. AnalogKid

    Bistable Multivibrator

    Hard to believe a uC-based switch interface would not have debouncing built into the firmware. Link to the board vendor site so we can read all about it? ak
  11. AnalogKid

    4011 IC

    The CD4093 is a drop-in replacement for the CD4011 and is the right part for this application. The timing will change slightly because the 4093's transition levels are different. If you want to stay with the 4011, add a 7.5M - 10M resistor from the output of the 2nd one to the inputs of the...
  12. AnalogKid

    SHUNT resistances value

    First thought - Add four Shottkey signal diodes, one each anode to the tops of R22-25. The junction of the four cathodes represents the peak value of the four currents minus one diode drop. This plus a comparator gives you a first-order error signal. For example: If the diodes come on at...
  13. AnalogKid

    SHUNT resistances value

    Looks good so far. But ... What if the current sharing among the four FETs is unequal? Worst case would be all 60 A through one FET. As I read the schematic, the circuit would not see this condition as an error, and the lone shunt resistor would be hit with 58 W - ish. ak
  14. AnalogKid

    Two relays in series with flyback diode.

    Tha is correct. I slipped over to the 1/2 A line. oops. ak
  15. AnalogKid

    Two relays in series with flyback diode.

    I'm sure that if you compare an automotive (32 V) fuse with a generic 1/4" (250 V) fuse, the timing characteristics could be quite different. But most of that is because automotive fuses are designed for a specific application environment. You have to be careful when comparing different fuses...
  16. AnalogKid

    Two relays in series with flyback diode.

    Also, 5 mm fuses are available with welded-on leads so they can be soldered onto a pc board as a through-hole component. ak
  17. AnalogKid

    Two relays in series with flyback diode.

    Incorrect. The voltage and current ratings of a fuse are independent. The 250 V rating means that it can interrupt a 250 V circuit without internal arcing or bursting the case. A 0.063 A / 250 V fuse will work just fine at 5 V, 12 V, whatever. 63 mA, 80 mA, and 100 mA are common values; also...
  18. AnalogKid

    PAL vs NTSC?

    In round numbers, a single PAL frame has higher resolution, but NTSC has few motion artifacts because of the higher frame/field rate. ak
  19. AnalogKid

    PAL vs NTSC?

    I'm not sure what you are asking. Your use of lines per frame, frames per second, and overall video bandwidth all are incorrect. Are you asking about the frequency of the laser light used to read a DVD? ak
  20. AnalogKid

    Momentary Switch to directional DC motor

    Given the high currents involved, can you post a schematic or wiring diagram of the current system so we can see the rules of the road? ak
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