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  1. crutschow

    Audio . . . Delay? Buffer?

    I believe the video processing time is slower than the audio processing, so it's the audio that requires a delay My audio receiver has an audio delay that I set to about 30ms to synchronize my sound and video. I used a video and sound of striking a golf ball to set the delay. You might try a...
  2. crutschow

    What gauge of power and speaker wire?

    Typically you want the wire resistance to be a small percentage of the speaker impedance so it depends upon that and the length of wire. For example 20ga copper wire has a resistance of about 33mΩ per meter, so 3.5 meters of dual speaker wire would have about 7 * 33mΩ = 0.23Ω resistance, which...
  3. crutschow

    Astable multivibrator circuit making me astable

    Some tips: If you look at the Edit drop-down menu you will see the key shortcuts for common components, such as "G" for ground, "R" for resistor, "C" for capacitor, etc., and common commands such as F3 for Draw Wire, F4 for Label Net, etc. which save a lot of time when generating a schematic...
  4. crutschow

    Grounding a Ham Antenna

    The antenna looks like a nice, tall, ungrounded lightening rod, so no, it will not protect the antenna. If the lightening can travel several thousand feet from a cloud to your house, then it will have no problem also going a few extra tens of feet from the base of the antenna to ground. :eek:
  5. crutschow

    Astable multivibrator circuit making me astable

    Increase the value of R2 and R3 as I suggested (below): With the low resistor values and the higher gain of the normally oriented transistors, both transistors just tend to stay fully on. The oscillation frequency is lower, so you also have to increase the simulation time. You can also be able...
  6. crutschow

    Astable multivibrator circuit making me astable

    First rule of Spice. All Spice simulation circuits need a ground connection, so I added that. Also you had D2 in the wrong place. Note that you can use standard prefixes such as u, p, m, k, meg (not M), etc. for part values. And the circuit takes a few ms to start, so I extended the run time...
  7. crutschow

    Increasing the output voltage of a step-down transformer by reducing the number of coils

    Yes, if you can get at where the tap is made. An autotransformer has just one winding, and a tap is made on that winding to get the desired voltage. Thus for 120V from a 240V input the tap is about 1/2 from the bottom.
  8. crutschow

    Astable multivibrator circuit making me astable

    If it doesn't, post the .asc LTspice file and I'll take a look at it.
  9. crutschow

    Increasing the output voltage of a step-down transformer by reducing the number of coils

    Yes, since isolation is not needed for this purpose, it could likely be an autotransformer since they are smaller and cheaper to build. But you can still easily add windings to put in series with the output to increase the voltage. It doesn't appreciably affect the output voltage for a given...
  10. crutschow

    Increasing the output voltage of a step-down transformer by reducing the number of coils

    You are assuming that the transformer won't saturate from that, but that's iffy, since most commercial transformers run close to saturation in normal operation (to save on core cost). The label says 220V to 110V, so at 240V it will likely produce 120V out.
  11. crutschow

    Astable multivibrator circuit making me astable

    Falstad simulator may not properly model reverse operation of a bipolar transistor. Yes, LTspice does have a somewhat steep learning curve but there are many sample circuits and tutorials to help with that. You don't have to have a career in electronics, just a hobby interest, to find a good...
  12. crutschow

    A simple electric fence idea

    Yes. My point was, they use DC for that, not AC.
  13. crutschow

    A simple electric fence idea

    What exactly? Any amount of AC current the body above 10mA is dangerous. I would not count on a spontaneous recovery of the sinus rhythm from any value of AC current that has caused cardiac arrest. The defibrillator uses a large DC pulse.
  14. crutschow

    A simple electric fence idea

    Well if you go to the dangerous side of that, I trust you have good attorney to defend you against a wrongful death suit. :eek:
  15. crutschow

    A simple electric fence idea

    The impedance should be sufficient to limit the current to below 10mA. Also to be double safe, the applied voltage should be short duration of perhaps 100ms and interrupted periodically (once a second) to allow a person to let go of the wire and minimize the chance of electrocution. This can be...
  16. crutschow

    Astable multivibrator circuit making me astable

    Below is an LTspice simulation showing the characteristic curves of the same NPN transistor operating in both the normal and inverted mode: Note that Q2 still operates as a transistor when inverted, but the gain is very low with a Beta of about 3, versus over 130 for the normal connection. One...
  17. crutschow

    A simple electric fence idea

    The microwave transformer has about a 10:1 turns ratio whereas an ignition coil is usually 100:1, so the fencer output voltage would be reduced to about 800V, which may not be enough to get through the hair on an animal. My simulation also shows that the large inductance of such a transformer...
  18. crutschow

    A simple electric fence idea

    Certainly good to do if you have a Variac available. No slow electronikers allowed. :rolleyes: But it would need to go some above 100V before it starts stressing C2.
  19. crutschow

    A simple electric fence idea

    Since there is a possibility of overvoltage being generated on capacitor C2 if there is a component or wiring error, I recommend the following when you do your first "smoke test": Connect a battery powered multimeter set to the 100-200V DC range and connect it across C2 with clips so you don't...
  20. crutschow

    Lead acid battery minimum discharge level

    That shouldn't be a problem with most modern sealed (zero-maintenance) batteries.
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