Search results

Search Forums New Posts
  1. crutschow

    A simple electric fence idea

    Only for the person that is building and testing it, if they feel uncomfortable working on a main's circuit. As Minder noted, the waste-spark dual output coil will provide isolation from the mains to the output.
  2. crutschow

    A simple electric fence idea

    The Q1, D4 combination will actually limit the voltage to below 90V if the SCR fails open (I view the chance of the primary of the auto coil failing open rather remote.) But an added Zener to protect the circuit is probably a good idea.
  3. crutschow

    A simple electric fence idea

    That's a little too simple. A fencer powered directly from the un-isolated 220Vac is inherently dangerous and not allowed. Also the electrical power should be periodically interrupted (typically about once per second) to allow the person/animal to escape the fence. Below is the LTspice...
  4. crutschow

    Lead acid battery minimum discharge level

    See no reason for that. There has to be a current path between the two battery terminals to discharge it, and just setting it on concrete wouldn't do that. Sounds like an "old wives tale".
  5. crutschow

    Connecting a LED directly to a 230v isolation transformer

    An efficient way to limit the LED current is to use a series capacitor of the proper size, instead of a resistor. For example for 20mA of peak current at 50Hz, 230Vac, the value should be about 200nF. The capacitor must be non-polarized with a 400V minimum voltage rating. A inverse connected...
  6. crutschow

    Lead acid battery minimum discharge level

    Discharging them to 10.5V (or below) won't. Discharging standard lead-acid batteries to a low level can damage the plates due to shedding of lead sulfate from the plates. Thus, for best life, it it recommended that standard Pb-acid batteries be discharged to no more than 50% of it's capacity...
  7. crutschow

    how to create autoswitching circuit for 12v ups for router

    As I said, it depends upon the relative voltage between the power supply and the battery. Which voltage is larger and by how much?
  8. crutschow

    how to create autoswitching circuit for 12v ups for router

    If the 12V adapter voltage is slightly higher than the battery voltage, you could use a Schottky diode at each output to isolate the load. If the adapter can tolerate the battery voltage on its output when it is unpowered, than you only need one diode. If adapter voltage is not larger than the...
  9. crutschow

    Pulsate 1.5v D cell battery

    Below is the LTspice simulation of a two BJT astable (relaxation) oscillator the operates from 1.5V, and uses a capacitor doubler circuit to generate a short periodic current pulse (red trace) in an LED (since 1.5V is not enough to power a visible LED):
  10. crutschow

    Pulsate 1.5v D cell battery

    For 1.5V operation you might be able to use a BJT astable oscillator. But what load are you trying to drive with the 1.5V signal?
  11. crutschow

    How do I measure a material's capacity for ultrasonic media use?

    Define what you mean by "ultrasonic media use"(?).
  12. crutschow

    Can Damper Diodes be used at high duty cycle current?

    They can be used at a higher duty-cycle as long as the maximum average forward current rating is not exceeded.
  13. crutschow

    What is quality level and reliability of cheap chinese diodes?

    No matter what, you need low current ( a couple hundred mA), fast recovery diodes, (such as Schottky types) to rectify 20kHz signals. Larger diodes have more junction capacitance which can affect the accuracy of the rectified signal.
  14. crutschow

    Inrush Current for Capacitive Load

    A step input has infinitely high Fourier frequency components, so the initial capacitive impedance is zero, not infinite.
  15. crutschow

    Issues with kenwood KAC-511 1000w amp

    How many subs are connected and what is their impedance?
  16. crutschow

    Help with what to check next - pre-amp distorting at high/full volume

    Likely it's a design problem with the amps not having enough dynamic range, so they clip the signal at high levels. Don't see how you can solve that without having a circuit schematic. Does it have an internal power supply?
  17. crutschow

    How do I make an opamp stereo mixer?

    What do you mean? What is "that"?
  18. crutschow

    How do I make an opamp stereo mixer?

    Okay, like this:
  19. crutschow

    How do I make an opamp stereo mixer?

    Okay, I think I better understand what you mean. So if the resistor value to ground is reduced further relative to the pot resistance, than the mid setting attenuation will be higher. For example, below is the plot for a 3kΩ added resistor: That gives a midpoint output of -25.4dB relative to the...
  20. crutschow

    How do I make an opamp stereo mixer?

    You just need an audio op amp that can operate at 5V. Look at the OPA134, OPA2134 and OPA4134, or the MC33171 single, MC33172 dual and MC33174 quad opamps, or the MC34071, MC34072 dual and the MC34074 quad.
Top