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  1. AnalogKid

    Need to draw 5 amps

    Note that while ATX power supplies do have overcurrent protection on the output, that protection does not kick in unto about 115% of the rated output current. So a 30 A output like the one in the photo will happily supply close to 35 A into whatever the load is if the load has a problem. ak
  2. AnalogKid

    Adding filtered signals from the same source

    I just took another look at your schematic. It will not work the way you intend. There is one single-pole 636 Hz highpass section and one single-pole 636 Hz lowpass section. When you combine these two the result will no change in tone whatsoever, but there sill be significant phase...
  3. AnalogKid

    Adding filtered signals from the same source

    What you are not seeing is that your circuit and the one in post #3 are functionally identical. By your description and schematic you start with one low output impedance voltage source and use it to drive three filter networks in parallel. That is what the first opamp and the three adjustable...
  4. AnalogKid

    Future

    There is nothing in you problem description that ties the motor to the alarm electrically. Can't you just start the blender and then start a timer? You can get a multi-stage kitchen timer for $10. My $100 microwave oven has one built in; it will time four stages with or without the microwave...
  5. AnalogKid

    Substitute transistor.

    There is nothing wrong with using another 3055 as the darlington driver. ak
  6. AnalogKid

    Relays - non latching or latching?

    If the lights get more dim as more are turned on, that indicates that the power source for the lights is not well regulated or is being overloaded. What is the 12 V source? manufacturer, model number, photo, etc. AC or DC output? Regulated? Max rated current? Number of lights? Power or current...
  7. AnalogKid

    POWER SUPPLY - REGULATOR

    When you get the supply, please rip off the lid and post a photo. I'd like to assess the design. ak
  8. AnalogKid

    POWER SUPPLY - REGULATOR

    4 A is too close to the pump rating; you don't want the supply running at 95% of capacity continuously. I'd go with the 5 A. The 7 A will run cooler, but will be more money. ak
  9. AnalogKid

    Trap Door Project: DC BATTERY BACKUP for 12VDC Linear Actuator

    http://www.powersonic.com/images/powersonic/sla_batteries/ps_psg_series/12volt/PS-1212_11_Feb_21.pdf Powersonic is my fav SLA company. They have excellent products and app notes. I still think a traditional charger is overkill for you and this application. So what if the battery is not topped...
  10. AnalogKid

    How do I easily convert a stereo power output to mono?

    Maybe you mean the output stages won't fight... I referred to Phil only in the context that Ringo (universally regarded as "worse" than Phil) was playing with a handicap and better than most people think. I'm not what you would call a big fan of his, but I recognize that the guy was perfect...
  11. AnalogKid

    Need input on design for LED circuit

    It looks like the switch on the far right and the six TIP31's form a multiplexer. If that is the intent, this circuit has several problems. Once the TIP31 base is connected to Vcc, its emitter will be fixed at about 0.8 V below that and will not move regardless of the varying analog signal on...
  12. AnalogKid

    Trap Door Project: DC BATTERY BACKUP for 12VDC Linear Actuator

    Sealed lead acid (SLA) batteries are built for long life in backup power applications. Depending on the motor energy required, you might not need anything more than a large capacitor, and at 12 V you can get a whole lot of capacitance for half the cost and 1/10th the effort of doing a small UPS...
  13. AnalogKid

    Headphones mute speakers when plugged in

    There are at least two different places to adjust the audio volume in a Windows system. Are you sure you have things turned up?
  14. AnalogKid

    Help with compatability

    Not necessarily. There is a difference between the maximum voltage headroom of a 4-20 mA output and the minimum voltage drop of a 4-20 mA input. Please post the datasheets (or links). ak
  15. AnalogKid

    'Chasing' LEDs

    0 for 2. Second, the 3915 is the VU-meter part. In terms of activating voltage levels, it's comparators are spaced apart logarithmically rather than linearly. First, both parts are based on comparators rather than linear amplifiers, so the visual effect in "bar" mode is the same as with a...
  16. AnalogKid

    Having trouble analyzing this power supply..

    Z2 and Z3, as conventional forward-biased diodes, combine with the transistor's base-emitter junction and the emitter resistor (100 ohms) to form a 6 mA current sink circuit. This presents a minimum load on the power supply even when there is nothing attached externally. The output of the...
  17. AnalogKid

    'Chasing' LEDs

    Another non-uC approach is a dual-opamp ramp oscillator driving two LM3914's in series. ak
  18. AnalogKid

    'Chasing' LEDs

    Ground rules: Diode Vf = Vbe = 0.6 V. Vcesat = 0.1 V. LED Vf = 2.0 V Rightmost transistor = Q1. Leftmost transistor = Q5. The leftmost transistor in a 15 stage circuit = Q15. Q1 comes on first. 0.6+0.1+(2x2.0) = 4.7 V, so the voltage across the 390 ohm resistor is 7.3 V and the current...
  19. AnalogKid

    'Chasing' LEDs

    While the circuit in post #5 can be expanded to 15 stages (barely), neither the timing between stages not the LED brightness will be a constant across one complete cycle. Two 8-bit shift registers in series requires a total of only two output lines from the microcontroller, and both the timing...
  20. AnalogKid

    Having trouble analyzing this power supply..

    Again, what are the values of the two unmarked zener diodes, and are you sure they are installed the way you want them? Again, what is the exact value of the capacitor marked 33 mf? mf is not a valid electronic component abbreviation. ak
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