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  1. K

    Electrocardiogram (ECG) "wave calculator"?

    Lots of stuff out there to pick from! Google: ECG microcontroller ECG Arduino ECG PIC ECG PICAXE Heart pulse counter circuit Ken
  2. K

    underground fault locator

    In determining how to determine were a fault is, you need to define what constitutes a fault: 1. Normal/degraded signal/current/voltage on the conductors 2. Fault Open (full or partial) 3. Fault Short (full or partial) to external conductors 4. Fault Short (full or partial) between internal...
  3. K

    Electrocardiogram (ECG) "wave calculator"?

    Most ECG monitors just display the "heart rate" digitally. This is calculated using the reciprocal of the time between QRS waves in minutes. They also may alarm on tachycardia or bradycardia, but that's just based on heart rate and alarm point settings. This would most easily be done with a...
  4. K

    Circuit for converting Fixed feed into single 'pulse'.

    You can use a 555 IC monostable circuit. A level change on the input will give just a single, fixed length, output pulse. Can you provide a sketch of the wiring of the current circuit, including voltages? Ken
  5. K

    Timer and Controlling a School bell

    Are all the clocks in your school controlled form a central clock? If so, this might be used to input to a microcontroller. The microcontroller can count seconds and ring the bell at the appropriate times. If not, you could use the internal pulses from a hacked, battery desk/wall clock the...
  6. K

    Is working with mains power supply safe for beginner, or should I hire a professional

    In the mean time...go on the web and see if you can find a schematic for the amp. Post the make and model here too. Those of use with a bit of search experience might be able to find it...too help your grandfather. Ken
  7. K

    Pulse Width control circuit

    Not going to happen. MIG welders are "constant voltage" devices. TIG/Stick welders are "constant current" devices. The internal components are very different. You don't just change cables, make a few tweaks, and the MIG is magically a TIG. Were that the case you would see MIG/TIG/Stick machines...
  8. K

    Is working with mains power supply safe for beginner, or should I hire a professional

    Unless the tube amp is a throw-away, go hire a professional. Connecting and disconnection things without knowing what or why you;re doing it is not only a waste of time, but dangerous with the high voltages present on tube amps. Yes, I started my childhood electronic career with tube...
  9. K

    transformer help needed

    mahone, You never said what circuit the transformers were being use in. Rewinding the primary without finding out what the cause the failure will only give you lots of practice in rewinding the primaries again...and again...and again. Ken
  10. K

    transformer help needed

    Unless there is something really special about this transformer, it seems like it would be more cost effective to just buy a new one...after figuring out why you're blowing windings. Since you pulled the primary off, I assume this isn't the type that have a thermal fuse buried in the winding. Ken
  11. K

    Automated Sliding Door

    You didn't say anything about how this door is to be used...for people?...for chickens? You might want to think about a safety mechanism/circuit to prevent someone of something getting stuck in the door as it closes. Ken
  12. K

    help with picaxe

    A R/C on the output! I thought you meant you were using an R/C on the ADC input to establish a varying reference voltage? Ken
  13. K

    help with picaxe

    Though I haven't done it, I would guess that you can fade an LED with an 08M2 in software. Use a timed up and down count controlling a PWM output. Ken
  14. K

    help with picaxe

    Take a look at the PICAXE manual. "button" is a built-in BASIC command to debounce an input. Ken
  15. K

    help with picaxe

    I agree with Steve. It's not a toy, it's a cheap, viable microcontroller. It may be a hammer compared to a belt-fed, pneumatic PIC nail gun, but it does what it does. I use them at work. Ken
  16. K

    help with picaxe

    PICAXE uses BASIC for programming. The real experts at getting you what you want would be at the PICAXE forum: http://www.picaxeforum.co.uk/forum.php Ken
  17. K

    RF project

    By "010101010" do mean just off-on-off-on-off-on-off like a remote switch, or is this a digital byte/word? Ken
  18. K

    need help with timing issue on an astable

    When you connect pin 4 high, the "reset" function that I described in post #2 is disabled. The timing is then set by internal comparators. Attached is a circuit I designed that turns the astable off by clamping the timing capacitor at 0.33 Vcc. When your logic activates the astable, the...
  19. K

    need help with timing issue on an astable

    When a 555 astable is normally oscillating, the timing capacitor ramps back and forth between 0.66 Vcc and 0.33 Vcc. Pulling the reset pin low discharges the timing capacitor to near 0V. So when you release the reset pin, that first time period is determined by the capacitor ramping from 0V to...
  20. K

    need help designing a circuit with time delay

    Google: PIR motion detector Ken
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