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  1. AnalogKid

    Electronic Development

    What I hear: Rather than couple the moving lever to a disc that rotates near an optical switch, you want to mount an accelerometer directly on the lever and run the flexible signal wires to the processing circuit, eliminating the mechanical alignment needed for the slotted disc / optical...
  2. AnalogKid

    Need something for just switching between 3 lights

    Why is remembering the last active state when powered off a requirement? ak
  3. AnalogKid

    Need something for just switching between 3 lights

    Remembering the last state when powered off is the key req. For this you need something that remembers (duh), such as a microcontroller with a bit of flash or eeprom memory, a very low power battery-backed circuit, or latching relays. The relays are by far the most expensive way to go, but you...
  4. AnalogKid

    Delay Relay

    I think the OP is gone. Don't discount long wires as delay elements... Broadcast quality video recorders of the 60's-70's used a pulse-integrating FM demod. Older RCA machines had a coil of coax cable strapped down in the middle of the demod pc board. The reflection from the unterminated end...
  5. AnalogKid

    Electronic timer clock

    Re-thinking -- is reliable AC power available near the trap? Any AC-powered alarm clock will have a point between the power supply (where it gets its 50/60 Hz timebase) and the clock chip where a modification could be installed. ak
  6. AnalogKid

    Electronic timer clock

    Very. Someone probably already makes one, but where's the fun in that? The least hardware effort uses a small microcontroller to do the counting, drive the display, and interface with the light beam system. But that takes programming skill, a complier, device programmer, etc. If you don't...
  7. AnalogKid

    Delay Relay

    1. What is the control signal voltage: 5 V, 24 V, AC, DC, etc. 2. What are the characteristics of the relay being controlled: coil voltage, current, watts, manufacturer, part number, etc? ak
  8. AnalogKid

    Too good to believe...?

    I have no problem with the specs-per-dollar. Looking at the min timebase, memory depth, input impedance, screen resolution, and the probe connector, the whole thing might be nothing more than a PIC and a DSP. ak
  9. AnalogKid

    Power supply efficiency

    No. A supply of that type usually is around 75 to 80% efficient at full load. The 1.2 A input current is a way overestimated estimate. It might be the startup inrush current, bit it seems low for that. ak
  10. AnalogKid

    Hardware debouncing

    Yeah, how is that going to work? For a matrixed keypad, usually the system drives the rows and reads the columns (or vice versa). I suppose the system could continuously drive the rows while it has the 4 column signals going to 4 interrupt inputs. Or are you doing a software interrupt based...
  11. AnalogKid

    Hardware debouncing

    "in" the port expander, no (at least not in the ones I'm familiar with). It isn't all that smart. Often when a processor is involved, the debouncing is done in firmware/software. You are scanning the switch matrix anyway, so polling the returned signals to see when they stabilize is not a...
  12. AnalogKid

    Variable time on/off switch circuit, for model tree-house project

    If you want to build a timer circuit from scratch, this can be done with a CD4060 oscillator/divider, a couple of small diodes, and an output transistor. What is the peak current of the load being controlled? Is 4.5 Vdc the only power source available? ak
  13. AnalogKid

    Is the following a universal gate?

    Where did that come from? Of what use is a gate with external pins forced to a common logic level? The only condition that gives *any* gate usefulness is different logic levels on the inputs. No, any non-inverting gate cannot be a universal gate. The quote is technically correct, but implies...
  14. AnalogKid

    Is the following a universal gate?

    Agree, using the definition in post #1. ak
  15. AnalogKid

    Is the following a universal gate?

    With appropriate layers of DeMorgan's theorem, *any* gate with at least one inverting path between an input and the output meets your definition of a universal gate. The most common examples of parts you can actually buy would be a 2-input NAND or 2-input NOR gate. ak
  16. AnalogKid

    40 Floppy disks for...

    Too much. ak
  17. AnalogKid

    Short

    Is it shorted to ground because it is connected to ground, or is it connected to something else? Without you showing more of the circuit, and some information about its intended use to put things in some frame of context, it is very difficult to answer your question. What voltage AC or DC what...
  18. AnalogKid

    What solid state components can switch composite video (AV)?

    Normally I agree with 73, but not this time. I strongly recommend *against* CD4000 series analog switches for either audio or video. The on resistance varies greatly with signal amplitude, causing harmonic distortion in audio and differential phase / differential gain distortion in color...
  19. AnalogKid

    What solid state components can switch composite video (AV)?

    Composit video switchers are a thing of the past, but readily available on ebay...
  20. AnalogKid

    555 or one shot

    OR, let's assume 4 mA at 12 V for the LED. A 2.2K or 2.7K resistor and a 1500 uF capacitor will hold the LED on for the required time. The LED will fade away rather than snap off. No chips, no transistors, no PICs, no Arduinos. One R, one C, that's it. ak
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