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  1. AnalogKid

    Boost low volts at a few amps

    1. Large capacitors as close to the boost converter input as possible. 2. Search ebay for a larger boost converter module. You cannot possibly build one for less than you can buy one. ak
  2. AnalogKid

    Problems with using LM324 as an inverting amplifier

    That seems pretty clear. To do this, you will need a rail-to-rail opamp powered by at least +5 V and -5 V, or a conventional opamp powered by +8 V and -8 V or more. That is much less clear. The problem is that in electronics the word "invert" can mean two different things. Inverting a...
  3. AnalogKid

    Problems with using LM324 as an inverting amplifier

    That is a non-inverting amplifier, the opposite of what you want. ak
  4. AnalogKid

    Multivibrator of varying frequency

    Yes, and the circuit would not oscillate. Why? ak
  5. AnalogKid

    Multivibrator of varying frequency

    For absolutely no reason, I didn't see the ***two*** base resistors in a circuit I first built in the 60's. Doh. Deleted the post. ak
  6. AnalogKid

    Step down converter and - lead

    It depends on whether or not the 46/12 converter is galvanically isolated or not. It is is, then no. If it isn't, then maybe. And on top of the maybe will be a ton of noise. A wiring diagram would help. ak
  7. AnalogKid

    Reduce off grid freezer startup current?

    I'm not familiar with your freezer, but a. only 57.5 VA total power consumption seems way too low b. if the running power really is only 58 VA, there is no way the startup current would overload a 1200 W generator. ak
  8. AnalogKid

    How to make this circuit unity gain?

    Really decent audio needs high transient currents, but the transformer secondary's inductance limits how fast it can supply current to the filter capacitors. Big ass capacitors store a lot more energy, and so they discharge less on those transients, presenting a lower dynamic impedance voltage...
  9. AnalogKid

    Multivibrator of varying frequency

    R5 and R6 are two resistors in series between two voltage sources. If the two voltages are not equal, the voltage at the center node formed by the two resistors can be calculated using Ohm's Law. The corner frequency is calculated using the equation for the corner frequency of a single-pole...
  10. AnalogKid

    Multivibrator of varying frequency

    R5 works with R6 to form a voltage divider. This sets the voltage at the Q1 emitter, which affects the oscillator frequency. Also, R5 and R6 work with C1 to form a low pass filter. The corner frequency is 7.5 kHz, which seems a bit high to me. It changes the edges of the V2 square wave into...
  11. AnalogKid

    How to convert RS-485 to RS-422

    As far as I know, there is no such thing. In a single-channel application like yours, RS-422 and RS-485 are identical. ak ak
  12. AnalogKid

    How to convert RS-485 to RS-422

    485 and 422 are essentially identical hardware protocols with one major exception. 422 allows for only one transmitter on a bus, and it is permanently enabled. 485 allows multiple transmitters; only one at a time can be enabled, and the others are in tri-state (high-impedance) mode, If you...
  13. AnalogKid

    Multivibrator of varying frequency

    Because R1 and R4 are much smaller than R2 and R3 (this is correct), it is R2 and R3 that set the charging currents for the capacitors. That is why changing Vmid will change the frequency or oscillation. ak
  14. AnalogKid

    Cleaniness for non cleanroom

    More is better than less. ak
  15. AnalogKid

    Transmitter and Receiver

    ebay wireless doorbell. $3 ak
  16. AnalogKid

    Wiring instructions for timer

    You did not post any instructions, or any link to instructions, or any other useful information. Nice photo. ak
  17. AnalogKid

    Simple Low Frequency Sound Generator

    You continue to mix the speaker rating (3 W) with the electrical power of the audio signal driving it (unknown). You can calculate the signal power by measuring the resistance of the disconnected speaker coil (don't trust the label), and then measuring the AC voltage across the speaker when...
  18. AnalogKid

    Calculating the Total Energy Released by a Capacitor up to Defined Points in Time

    Because Joule is a proper name, it is spelled out lower case (joule) but abbreviated with a capital letter (J). ak ps. I'm old, and I have old camera flashes. Watt-seconds are us.
  19. AnalogKid

    Calculating the Total Energy Released by a Capacitor up to Defined Points in Time

    The transistor is acting as an electronically-controlled on/off switch. The total energy in a capacitor is: E = 1/2 x C x V^2 -- Energy equals one-half times the capacitance (in farads) times the square of the voltage. The unit is watt-seconds, abbreviated Ws, or W-s To calculate a partial...
  20. AnalogKid

    Simple Low Frequency Sound Generator

    Driving a speaker rated to handle 10 watts, and producing 10 watts of electrical energy are two very different things. What is the final result for? How loud does it have to be? Four AA batteries have a total energy of around 17 watt-hours, but not all of that is available and electronic...
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