Type: Posts; User: BradtheRad

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  1. Closed: Re: Problem with Logitech Audio PCB (No Sound Output)

    I'm looking at the 0V readings at pins 5 through 10, on IC#2. That can't be normal.

    IC#1 gives 0V only at pin 9 which is labelled ground.
  2. Replies

    Closed: Re: Single supply low-side shunt amplifier

    Your schematic is common-base operation of a transistor. Its characteristics are:
    * low input impedance
    * high output impedance
    * high gain.

    By that reckoning it fits your purpose. A semblance...
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    Closed: Re: Halogen Lamp Limit Resistor?

    Although 10W is calculated dissipation, nevertheless it's wise to make your resistor rated for higher than that. Consider putting several one ohm resistors in parallel. It's easy to add or subtract,...
  4. Replies

    Closed: Re: Halogen Lamp Limit Resistor?

    This article on halogen bulbs points out ways they are different from normal incandescents. (Halogen type has a cycle of filament metal being vaporized and redeposited.)
  5. Replies

    Closed: Re: Halogen Lamp Limit Resistor?

    As Brian says, it's more efficient to pulse the headlight.
    Nevertheless it's interesting to figure out how to achieve the resistive drop.

    To send 50W through your headlight, apply 8.5 volts...
  6. Replies

    Closed: Re: Multiple AC inputs relay (light PLC)

    This can be done by putting resistors inline with the input signals. The weighting proportions are achieved by making differing ohm values. Mix them through a final resistor, to produce an output...
  7. Replies

    Closed: Re: Active HF phase shifter?

    It's an idea worth some experimentation.
    Or to have a potentiometer choose how much comes from a capacitor and how much from an inductor.
    This simulation selects a range between phase advance or...
  8. Closed: Re: High power efficiency oscillator topologies?

    Sorry, I wasn't certain as to what waveform you want. This sine wave oscillator has a resonant current loop based on two capacitors and one inductor. They carry several mA as oscillations build. The...
  9. Closed: Re: High power efficiency oscillator topologies?

    Multivibrator, frequency depends on capacitor value. 6pF yields 130 MHz.
    Output transition is a few volts. Draws about 1mA from 3V supply.

    Modified from initial schematic found at link below....
  10. Replies

    Closed: Re: Subtract two dc voltages.

    By installing a capacitor between the two sources, rapid zero-crossings are detectable. The capacitor produces spikes.
    However it may also produce spikes from abrupt transitions which are not...
  11. Replies

    Closed: Re: Subtract two dc voltages.

    Install a resistor between the two sources. One source becomes ground for the other source. Measure voltage across the resistor to read differential or subtractive value.

    As an alternate method,...
  12. Closed: Re: How to add the outputs of a different voltage double ciruits

    Rework one circuit so it outputs negative polarity. Connect your load across the two outputs. This method works if the two ground icons represent a single ground.

    Or, the output stages can be...
  13. Replies

    Closed: Re: Active HF phase shifter?

    By adding an inductor to the capacitor, attenuation is not as severe. Because you don't have a resistor involved. For 1-30 MHz range an inductor consists of a few turns around a pencil.

  14. Closed: Re: Difference between Differentiators and Comparators

    A differential detector is the input stage of a comparator.

    A differentiator performs a calculus function, differentiation. Its the counterpart of integration.
  15. Closed: Re: How to increase high frequency output power

    Can this be solved by impedance matching? Normally that is associated with the goal to maximize power transfer.

    Input arrives as a combination of voltage and current. The matching network raises...
  16. [SOLVED]Closed: Re: voltage and current waveforms spark gap

    For an example of unusual waveforms in Tesla coils, there's the kind that sings:

    "Dueling Banjos on musical Tesla Coils"
  17. Replies

    Closed: Re: Tuning Selectivity Factor

    The ratio of L:C plays a big part in performance. It's not necessarily easy to calculate what ratio is optimum in your application.

    Ohmic resistance has an effect on Q. Higher resistance causes...
  18. Replies

    Closed: Re: Help with medication timer design

    A big challenge is to open the housing and find out how to activate the internal switch. Then you must attach wires (very thin gauge) going to your external reed switch.

    Your Amazon link appears...
  19. [SOLVED]Closed: Re: voltage and current waveforms spark gap

    Falstad's animated simulator has a tesla coil in its Circuits menu. The run starts with voltage close to the level where spark occurs (10kV in positive portion of cycle. -10kV in negative portion).
  20. Closed: Re: One audio (Stereo ) master transmitter to multple audio reciver.

    There are IC's available as the basis for an FM receiver, by adding a few components. LM1800 is an example although I don't know if suits your purpose. You might find complete kits on Ebay if you...
  21. Closed: Re: Nominal current of diode bridge rectifier

    Waveforms through a diode are different, depending on whether your 3-phase is delta or star. It doesn't necessarily change average current, but it may make a difference in peak Amperes.

    If you add...
  22. Closed: Re: I am posting dsPIC30f2010 inverter circuits diagrams with PCB proteuse files and

    A new attachment may expire unexpectedly. Possible reason: not posted quickly.

    Try uploading your image again, and submit the post immediately afterward. In addition the post may need to contain...
  23. Closed: Re: Sine PWM calculated with pic, instead of using table

    The sine function produces negative values for a portion of each cycle. Does your switching scheme need positive numbers only? Or, does your loop calculate only the positive waveform?
  24. Closed: Re: Problem with Logitech Audio PCB (No Sound Output)

    The power supply appears to be at the left edge of your photograph:

    4 diodes D1 D2 D3 D4

    Two labels 'AC' where wires may be soldered

    Largest capacitor on the board

    Measure DC voltage on...
  25. Replies

    Closed: Re: Battery Bank Voltage Halver

    Step-down circuit using capacitors and transistors. 48V supply, load gets 23V. It may be possible to get 24V, if the battery bank puts out 49 or 50V.


    The capacitors must carry several...
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