Search results

Search Forums New Posts
  1. AnalogKid

    help needed on first project, led counters with key reset

    While this certainly can be done with a PIC, AVR, Arduino, etc., it is not too large for an all discrete design. The displays and their drivers are a constant. That leaves 12 chips: 4 counters 4 latches 4 magnitude comparators ak
  2. AnalogKid

    help needed on first project, led counters with key reset

    What you describe sounds more like one counter group that drives its own displays, plus it drives a latch group with its own displays. How many days max? ak
  3. AnalogKid

    How to subtract 10 ohms from a 200 ohm resistive load?

    or 4.22 K at 1%. ak
  4. AnalogKid

    Alternating relays momentary closure

    Because your circuit drives the timers with latched outputs, there is no reason for a true monostable. A simple pulse differentiator gets you the same output pulse width for the same components. Since you have one gate in there, one more gate can replace each 4538 section and eliminate the...
  5. AnalogKid

    Alternating relays momentary closure

    I just noticed that in your original schematic the 4013 flipflop does not toggle. To do so, the -Q output is connected to the D input. Also, there is no switch debouncing. ak
  6. AnalogKid

    Alternating relays momentary closure

    First pass. Since all gates are acting as inverters, the 4093 can be replaced by a Schmitt-input hex inverter such as a CD40106. If the relay coil current is below 100 mA -ish, R5/Q1 and R6/Q2 can be replaced by 2N7002's. Multiple switches can be connected in parallel with SW1. Use twisted...
  7. AnalogKid

    Alternating relays momentary closure

    Unfortunate, but not a deal breaker. It comes down to availability and reliability. Which is better for you, two relays with contacts rated for at least 4 A DC, or two power darlington transistors (TIP125)? BTW, I wasn't suggesting changing the solenoid power supply, just the connections to...
  8. AnalogKid

    Alternating relays momentary closure

    That was based on running the solenoid current through the switch. Can the solenoid coils be pulled to GND? This makes it easier for the solenoid voltage to be different from the circuit voltage. ak
  9. AnalogKid

    Alternating relays momentary closure

    More thoughts... 1. If you use the button press as the timer for the relay coils, you eliminate both monostables and replace them with gating. Now it's just one toggle and some NAND gates. 2. BUT - If one end of the switch does not have to be grounded, now it's just one CD4093, two...
  10. AnalogKid

    Alternating relays momentary closure

    Sorry, I misread your first post and thought the twin-coil latching thing was a relay. oops. I'll look for my other circuit. ak
  11. AnalogKid

    How To Detect When A Line Goes Low

    You should post your circuit. A 555 is designed specifically to reject supply voltage variations. ak
  12. AnalogKid

    Alternating relays momentary closure

    I have a circuit from another thread that does all of that with one hex inverter. This is much less work:
  13. AnalogKid

    How To Detect When A Line Goes Low

    I'm not an expert on bike electrical systems, but based on my auto designs I don't think you need a voltage regulator for the 555. Power transient protection should be good enough in a 6 V world. The relay part makes this thread make sense. And I agree that there is no substitute for getting...
  14. AnalogKid

    How To Detect When A Line Goes Low

    It isn't harder than you thought, we're just coming up to speed. Just to be clear, you are after a total replacement for the original series flasher - yes? If so, then the circuit has to be such that the turn signal switch both enables the flasher and directs its output to the correct bulb...
  15. AnalogKid

    How To Detect When A Line Goes Low

    It sounds like the flasher is a series bi-metal switch, and your LEDs do not draw enough current to make it cycle. You can test this with a resistor in parallel with one of your LED bulbs. Something sized to pull 1 A should make the original flasher flash. If that works, it tells us more...
  16. AnalogKid

    is this correct!!! or there is any other way?

    Rated Voltage = 27 ??? Part number?
  17. AnalogKid

    Solid state solution advice

    Long-term, I've found that bipolar power transistors are more reliable then power MOSFETs in 1-off automotive projects. The TIP29 and TIP30 are complimentary bipolar power transistors rated for 1 A collector current, and make excellent low-current power switches. If the peak current being...
  18. AnalogKid

    Solid state solution advice

    Would 1 A transistors, such as a TIP29/30 be safely overrated for this application? ak
  19. AnalogKid

    Solid state solution advice

    Not counting the coil current of another relay, are any of the relays controlling significant power, such as more than 1 A? What does N/S/F stand for? ak
  20. AnalogKid

    Circuit that sends 1 pulse when input goes high, 2 pulses when input goes low

    For a 50 mA output stage that pulls a +12 V load down to GND, add a 2N7000 or 2N7002 to the output in post #25. ak
Top