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  1. AnalogKid

    Changeover Switch Relay?

    I'd change it to switch the V+ rather than the ground, but I like yours better. ak
  2. AnalogKid

    Changeover Switch Relay?

    I agree with CDRIVE's concerns abut the limit switches. Pending additional information, here is a first pass at a motor reverser. The hard part is finding a power relay that will switch 24 Vdc at 10+ A reliably and doesn't cost a fortune. DC switching is very different from AC switching in...
  3. AnalogKid

    ADC to PC; best/better solution

    Nice part. The Atmel XMEGA series has more than enough I/O pins and horsepower to act as the interface between the ADC and USB. So will any of the FTDI modules, or even an Arduino depending on how long the gap is between data bursts. ak
  4. AnalogKid

    Sensor for automated retail kiosk

    It sounds like there is a motorized door. Does the door block the sensor area at any time? Can the product block the sensor area at any time? In other words, if an optical array sensor were free, would it be the perfect solution or could it be fooled sometimes? And, what is the product that...
  5. AnalogKid

    Getting a led to turn on when voltage is under 3 volts on a battery

    What is "a box mode for vaping"? ak
  6. AnalogKid

    Panic Alarm Project advice

    Is there any particular reason why a beeper or some other low-tech system is not applicable? Front desk / sales counter / bank teller alarms, silent or not, have been around for many decades, and the doorbell was invented over 100 years ago. Since you have to run wires to the button anyway...
  7. AnalogKid

    Changeover Switch Relay?

    CDRIVE - I think SW 1 connects to VS1 before any other connection, including a power feed to the relay armature. ak
  8. AnalogKid

    Voltage and current relation difference between Ohm's law and Power

    No, it doesn't. There is nothing to justify because your statement is incorrect. For a constant resistance, voltage is directly proportional to current. For a constant power, voltage is inversely proportional to current. ak
  9. AnalogKid

    Changeover Switch Relay?

    You can do exactly what you want with nothing but relays. What you want is a stepper relay, an old part way out of favor these days. Unlike a normal relay, a stepper relay armature does not switch the current to the load. It actuates a rotary cam that moves a switch that controls the current...
  10. AnalogKid

    FM headphones

    Any small digitally tuned FM receiver and ear buds will do this. $3 from china on ebay. ak
  11. AnalogKid

    Panic Alarm Project advice

    What is it you want this alarm to do? With audio files you need controls to select and play the file, an amplifier and speaker, etc. When I read panic alarm I thought of a very loud piezo beeper and a battery. ak
  12. AnalogKid

    Function Generators Role and Effect

    So this is the front end of a light beam communicator or audio transmitter? ak
  13. AnalogKid

    Common Cathode Triple digit display pinmap help!!!

    I agree with hevans, you're overthinking this. Make a table with 24 lines, one for each pin, and sit down with a power supply, one resistor, and a pencil. Mapping the entire device will tale less than 2 minutes, depending on how fast you can write 1a, 1b, etc. Note that you will be flipping...
  14. AnalogKid

    Function Generators Role and Effect

    In your image the scope shows a amplitude of 11 V, but Vcc is 5 V. How do you explain that? Also, connect the other scope channel to the input so you can see exactly what the transistor is doing. If the intent is to switch the LED on and off efficiently, with little or no intermediate dim...
  15. AnalogKid

    Sound activated switch advice

    Don't be tempted by the dark side...
  16. AnalogKid

    Sound activated switch advice

    The DC level on the Q1 collector is where you deal with the FET threshold voltage. Your circuit is a source follower, by definition *not* a level sensing switch. As mentioned above, if you want a more snappy response, change the output stage to be a saturated switch. It still might come on...
  17. AnalogKid

    Split Voltage for Driver IC & Backlight

    My guess is that you can do this with two 1.5 V AA cells in series. Picture them stacked vertically, the -end of the upper battery connected to the + end of the lower battery. Lower battery - terminal is system ground, connected to device pins 2 and 4. The center battery +/- connection is...
  18. AnalogKid

    Function Generators Role and Effect

    This discussion will go more smoothly if you post your schematic. In general, you are correct. The signal coming in from the function generator combines (adds or subtracts) with the DC bias at the base, and the combination determines the base current. The circuit you are describing can be...
  19. AnalogKid

    DIY UPS project

    200 Wh is not a lot of energy, meaning that you do not need a large UPS. In terms of 12 V batteries, you need 17 Ah. Unless you have a lot of ups component parts laying around, you probably cannot build this UPS for less than you can buy one. If you have an old UPS unit, then you need...
  20. AnalogKid

    Logic family selection

    Automatic handling of all possible error conditions is not possible. An absolute solution is not possible, because both failure logic states also are valid logic states for normal operation. If the input is a continuous waveform with a minimum frequency, you can add a monitor circuit to detect...
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