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  1. hevans1944

    Hi

    Welcome to Electronics Point, Victor. We have quite an eclectic gang of the usual suspects here, but yours is the first virtual pinball project that I have seen. Soooo... I went web surfing to see what that was all about. Amazing stuff out there, some of it commercial quality, built by amateur...
  2. hevans1944

    measure the current of a short pulse

    You may have problems trying to measure the voltage across a current-sensing resistor with an oscilloscope if the resistor is placed in the pulse output line to the PCB. There will be a large common-mode 6.5 V pulse at the resistor and you want to measure the voltage drop across the resistor...
  3. hevans1944

    Control stepper motor with PIC, maximum output frequency of PIC

    You are absolutely correct! I would estimate that 90% of the problems people pose here could be easily solved by the original poster if they had correct documents and took the time to read and understand the contents of those documents. It is fortunate that there is so much information available...
  4. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    Your code looks pretty tight! Good job, Adam. It does not appear to me that the WDT is used for anything except the 64 ms LED on-time. The off-time (used to charge the capacitor) appears to be a programmatic count-down, unless I am missing something reading the delay functions... The 12 μA...
  5. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    No hurry on getting one of the drivers to me. You did mention in post #44 that you had no idea how much off time was required to change modes, so that is what I want to test, eventually.. Until I am convinced I understand how to program my breadboard version (PIC10F206 SOT-23 devices) using the...
  6. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    Still on the learning curve using the MPLAB X IDE. I did take a "time out" to review the PIC 10F200 datasheet current requirements for the PIC in sleep mode. My hope that the current would drop to just a few microamperes during sleep mode was confirmed. The watchdog timer (WDT) current, Ipd...
  7. hevans1944

    Creating a latch circuit with logic gates

    Try the SN54AS109A series of positive edge-triggered J-K flip-flops. See attached data sheet. Note the K input is active low while the J input is active high. That means if you tie the two together it acts like a D-type flip-flop.
  8. hevans1944

    Creating a latch circuit with logic gates

    Well, I suppose you have to work within the constraints imposed by your customer (or worse, your boss). Maybe you can make a pitch for the PIC microcontroller + keypad idea, and if that is acceptable, save yourself a lot of time and effort.
  9. hevans1944

    230v Transformer, 115v input.

    Applying half the primary voltage to a transformer with a 240 VAC-rated primary will work, and the secondary voltages will be halved, but the transformer may not be able to deliver its rated current to the secondary windings.
  10. hevans1944

    Creating a latch circuit with logic gates

    What!? This is a homework assignment? I thought you were doing this for the pure fun of it, and as an intellectual challenge.
  11. hevans1944

    Charging a 450v 6800uF DC capacitor

    The resistor power rating was conservative because (1) I also recommended that it be used to discharge a fully charged capacitor and (2) I was too lazy to calculate how much power it would dissipate in a single discharge cycle (about two watts). So, I agree with you that a 5 watt resistor should...
  12. hevans1944

    Charging a 450v 6800uF DC capacitor

    Okay, in that case all we need is one 1N4007 rectifier connected across India's 240 VAC power line in series with the 6800 μF capacitor, anode of diode to phase side of line, cathode of diode to positive terminal on capacitor, capacitor negative terminal to neutral side of power line. It would...
  13. hevans1944

    Creating a latch circuit with logic gates

    It appears that any permutations of the code containing all the required digits (including the repeated digits) will "open" the lock. In your example, code 121992 is the valid code, but so is 119922, 219219, etc. Is this what you really want to do (after fixing the problems with the J-K...
  14. hevans1944

    Charging a 450v 6800uF DC capacitor

    From the nature of the query it is clear that the original poster has absolutely no idea of what they are attempting to do. This size capacitor charged to its rated voltage is capable of serious injury or even death. If I were moderating this forum I would close this thread.
  15. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    Oops! This appears to be a new requirement: pressing the switch for less than 500 ms and then releasing it to indicate a mode change to the LED driver module. One could hope that the release interval has some minimum requirement, say on the order of 500 ms, to avoid the 1 ms LED OFF duration...
  16. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    Roger on the switch actuation force being largeish. And I suppose that gigantic device near the top edge is the Schottky diode? And the little speck mounted next to the push button switch is the energy-storage capacitor? And the little part on the right side is a 220 resistor connected between...
  17. hevans1944

    flux / soldering paste..

    Maybe you loosen the screw and adjust the spacing of the prongs to be slightly less than the length of the part you are trying to remove. Tighten the screw and place the prongs on the device, allowing them to spread slightly so as to provide a "spring" grip. Now heat the part with the hot-air...
  18. hevans1944

    Help getting started on new project

    Seriously, a determined and highly competent individual with a lot of time available and no time-to-market deadline staring them in the face, could design and package something on the same size order as a Fitbit bracelet. It is fairly inexpensive to have someone manufacture and populate...
  19. hevans1944

    Microcontroller controlled by pushbutton for LED flashlight

    I just now got caught up reading this thread. All my tools for working with PICs and SMT components have now arrived, including a populated board and syringe of flux that Jeff mailed earlier this week that came in the mail today. Last week, I received the PICkit and four SMT PICs plus four...
  20. hevans1944

    I can't see how this will work

    Yep. And the CdS LDR is soooo non-linear. That is why I suggested earlier placing it inside a short tube with a tinfoil cap on the end that you punch a small hole into to let in some, but not an excessive amount, of light. As for artificial versus daylight, you might want to take a gander at the...
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