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  1. AnalogKid

    Why don't I get a Sine wave?

    Really? Got got got to disagree on this one. I don't think a microcontroller development system, language compiler, device programmer, and 100 lines of code are "simple" in any situation, let alone when compared to 1 transistor and a few passives. ak
  2. AnalogKid

    What would be the effect If I change 4700uF capacitor to 18000uF?

    I don't see the word "charge" in the thread title, post #1, or your quote. ? ak
  3. AnalogKid

    electromagnetism

    " And an inductor doesn't "inject a voltage". " I don't know. I was quoting you. ak
  4. AnalogKid

    nubie pot question

    If in is designed to work with a thermistor, that says many things about the input circuit. If it expects a 10K, then as a first-pass guess I's use two 10K's in your parallel circuit with a 20K pot. The problem is that you need the series resistance of the pot to force the averaging, but that...
  5. AnalogKid

    nubie pot question

    What is the "input"? A thermistor needs a source of current to bias it so a voltage can be produced across it. If you know the voltage, or current, or input impedance, or just about anything about the controller input, it is critical to working out what you are trying to do. ak
  6. AnalogKid

    electromagnetism

    "increase in flux" - Yes, not *all* flux. That is what he doesn't get. ak
  7. AnalogKid

    electromagnetism

    Actually, it is impossible to do. The lines of force extend to infinity, a difficult space to overload or saturate. Diminished increase in field strength as a function of increasing coil current? - Of course. But saturation in the same sense (and with the same consequences) of a transformer...
  8. AnalogKid

    Transistor mystery

    The circuit is not drawn in a traditional way, so it is a bit hard to understand at a glance. I've re-drawn it below. This is not a "normal" circuit, in that there is no source for collector current (no connection between the collectors and Vcc through a resistor, inductor, etc.). When SW1 is...
  9. AnalogKid

    Light Intensity Level Switch

    So something needs to store one light level so it can be held and compared with a later light level? If so, stored for how long, and what tells the receiver when to capture a new reference level? al
  10. AnalogKid

    electromagnetism

    No, you weren't. How would you know. Don't sell yourself short. Often times a newbie asking an honest question doesn't know how to distinguish between an experienced response and careless disregard from someone who don't know what he talking about. ak
  11. AnalogKid

    Help with PSU rating?

    Can you post a close up image of the writing on one of the relays? Also, a shot of the underside of the board, particularly the area around the power connector and 7812. If the relay coils are rated at 12 V, then it probably is the case that 100% of the input power goes through the 7812, and...
  12. AnalogKid

    electromagnetism

    First I've *ever* heard of a DC straight bar electromagnet "saturating", let alone "no long behav[ing]". anyone else? Except when you do. Um, no. Their purpose is to store energy in a magnetic field. Power conversion is the single most common use for inductors, both stand-alone and as parts...
  13. AnalogKid

    Anyone know where I can buy one of thes buttons?

    Devices like that often are a standard switch in a totally custom package. In your case there might be a small pc board inside with the cable soldered directly to it and a small "tact" switch. Often the button you press is an integral part of the enclosure with a live hinge, and hovers above...
  14. AnalogKid

    Light Intensity Level Switch

    So far, sounds like a fairly straightforward problem. One thing - are you familiar with the concept of hysteresis in electronic circuits? If not, you should read up on it. You have described what you want the circuit to do as the light level increases, but not what to do when it decreases. ak
  15. AnalogKid

    Light Intensity Level Switch

    How bright is the light? How far away is it? Is the light level changing slowly? This can cause relay chatter unless you add hysteresis. Is this indoors, outdoors in weather, exposed to caustic fluids or high temperatures? ak
  16. AnalogKid

    Need help to make telephone tap coupler schematic

    You started it, talking about a 600 ohm transformer. Did not. Did too. Did not. Did too... I think the OP does not have a grasp on reactive concepts. ak
  17. AnalogKid

    Diode for thermostat circuit

    OK, this is important. If the voltage on the relay coils is 24 Vac, you cannot prevent reverse direction current flow with a diode. If the relays are powered by 24 Vdc, you can. Got got gotta know which one it is. ak
  18. AnalogKid

    Car park sensor --> need help with component functions

    First, all 4 sections of an LM324 are operational amplifiers. a is configured as a trans-impedance amplifier, while b, c, and d are configured as comparators. I'll give you this one - C5 is a simple bulk filter capacitor to keep noise and voltage dips caused by transient currents off of the 12...
  19. AnalogKid

    Floating Dc Current Source

    Bob touched on this - floating from what? Any normal wall wart makes a 5 V or `12 V or whatever output that is galvanically isolated from the AC powerline - floating. If what you are asking about is a part of a larger system, then what is the overall power source? Also, if the current level...
  20. AnalogKid

    Enclosure Grounding, Insulation

    No, you're doing quite sell. 1. yes. 2. only basic insulation between the secondary circuits and chassis earth gnd. 3. Kapton tape is the standard for this. Most power supplies have the secondary circuit return separated from the chassis earth ground because they are designed for a general...
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