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  1. AnalogKid

    Need Help - Timer to complete circuit

    The timer board draws very little power, even when the relay coil is activated, so just about any wall wart will work. For the short power cable that comes with the board, red is +5 V and black is GND. If you have a universal type wall wart with a jack for a USB cable, then the cord from an...
  2. AnalogKid

    Need Help - Timer to complete circuit

    I prefer ebay to amazon, but both have lots of little timer modules. For the same $10, some have a digital display which makes for much more accurate setting of long delay times. Lose the batteries. Any little 5V wall wart like a cell phone charger or anything with a USB output jack will...
  3. AnalogKid

    Improve Biometric Lock

    Based on the thread title, are you asking about how to improve the fingerprint scanner? If so, what is the problem with the scanner now? Is there one fingerprint scanner for the entire rack, or one scanner for each bike rack position? ak
  4. AnalogKid

    Improve Biometric Lock

    Does anyone here know what you are talking about? Probably not. Please explain what you are talking about, what the part or circuit is, what it is supposed to do, what are the inputs and outputs. Is this a purchased product? Post a link to data, the vendor, photos, etc. What do you mean by...
  5. AnalogKid

    Honeywell Vista-20 programming questions

    Outstanding response, even if I don't like some of the answers. Both keypads (I thought I scrubbed all of the errant "panel" references) are hard wired 6150's; no RF anywhere. Entering the "off" code twice cleared the CHECK message. I no longer will bounce power at a keypad. Construction...
  6. AnalogKid

    Honeywell Vista-20 programming questions

    To ChosunOne and anyone else experienced with the Vista 20 - For my home alarm system I have one Vista-20 panel (with some zone doubling) and two 6150 (fixed-word) keypads. As part of some renovating I need to add a third keypad and document more of the system. 1. Is there a way to...
  7. AnalogKid

    Countdown Timer with Alarm Trigger

    This can be done with a CD4060 as the timing generator and a few small signal diodes to decode the output state, inhibit, and reset. ak
  8. AnalogKid

    Reversing polarity on push of a button

    Something about my initial reading led me to think he wants the latest state to be latched even when power is off, so the car starts up in the previous state. LightShow - ? ak
  9. AnalogKid

    Reversing polarity on push of a button

    For long term reliability, contacts should be rated for twice the load they carry. ak
  10. AnalogKid

    Reversing polarity on push of a button

    This can be done with a latching DPDT relay (also called an impulse relay) and a SPST momentary switch. The problem is finding parts rated for 20 A DC. ak
  11. AnalogKid

    Logic probe

    There is no hysteresis in the circuit. The circuit is a window comparator with a wide dead band. However, there is an overcurrent condition with the LEDs. You need to add one current limiting resistor (220 ohms-ish) between the Vcc input terminal and the D1/D2 anodes. Since at most only one...
  12. AnalogKid

    Op Amp Troubles

    The 324, and it's dual version 358, are hugely popular because they were the first opamps with at least one "rail" capability - both the input stage and output stage can function near (output) or below(input) ground (or what ever the negative rail is). But the output cannot get closer than 1.5...
  13. AnalogKid

    Op Amp Troubles

    What you are seeing is a "personality quirk" of older bipolar opamp designs. If you overdrive the inputs below the negative rail, the output saturates against the positive rail. Beyond that whole saturated output thing, this is a very unwanted signal inversion that can have catastrophic...
  14. AnalogKid

    Calculating thermal/heat dissipation for enclosure

    The power dissipation of a power supply is not a constant, or even a constant percentage; it varies with the load current it is supplying. How did you calculate it without knowing the details of the combined load? ak
  15. AnalogKid

    Muff Pedal Distortion Repair

    There is no on/off switch. Plugging in the guitar completes the battery connection to GND through the input jack. This is very common in instrument pedals. When you plug a mono 1/4" plug into a stereo jack, the ring contact is connected to GND through the plug sleeve. ak
  16. AnalogKid

    Muff Pedal Distortion Repair

    ok, oops (but there is an opamp version of this product). The static current of the circuit is the LED current. ak
  17. AnalogKid

    Muff Pedal Distortion Repair

    Another thought is to put the LED in series between the battery and the circuit. The opamp static current limits the LED current. ak
  18. AnalogKid

    Muff Pedal Distortion Repair

    During normal operation, is the LED on continuously, does it flicker with the music content, etc? ak
  19. AnalogKid

    Electronic Development

    I had not pulled up the datasheet yet; I see that now. Turning the outputs of one or more accelerometers into the equivalent quadrature squarewaves is going to take some number crunching. I get the desire for something that is reverse compatible at the interface connector so it can just be...
  20. AnalogKid

    Electronic Development

    What are the signals going to the uC: 1 sine/square wave, 2 sine/square waves (quadrature), something else? ak
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