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  1. AnalogKid

    Electronics help

    No, I didn't. And I quoted him so my response would be clear. The purpose of the wavy tracks is *not* to minimize time "losses". The only way to decrease propagation time is to change the substrate material, but that still would affect all traces equally. Maybe what he meant is that it...
  2. AnalogKid

    Looking for a small project to fill void

    https://images.search.yahoo.com/search/images;_ylt=A0LEV1KGaida_gwAoUFXNyoA;_ylu=X3oDMTE0dmt0M2VqBGNvbG8DYmYxBHBvcwMxBHZ0aWQDQjQ0ODNfMQRzZWMDcGl2cw--?p=Intercom+schematic&fr2=piv-web Many intercom circuits are a simple microphone amplifier with a switching arrangement to swap the inputs and...
  3. AnalogKid

    Looking for a small project to fill void

    Intercom.
  4. AnalogKid

    Electronics help

    Nope. The "wavy" tracks actually *increase* propagation time - intentionally. They are there to make all tracks in a group (such as 8 or 16 data bits coming off of a backplane, or a high speed differential signalling pair such as LVDS and Ethernet) equal length, not to minimize the propagation...
  5. AnalogKid

    Electronics help

    Solder paste is a paste made of solder. It is a bit wetter than toothpaste. It is applied to the pcb pads of surface mount components with either a paste mask and a squeege, like screening ink on a t-shirt, or a robot arm with a nozzle that deposits a very precise little dot. A paste mask is...
  6. AnalogKid

    Need help testing this circuit

    Both the anode and cathode of the SCR are tied to Ground. You tell me. Don't guess; think. ak
  7. AnalogKid

    remote controls

    My openers are early 70's, but I replaced the radios with Genie generics. They run off a wall wart and have a relay output, so they don't care what voltage is on the switch input of the old opener. $30 at Lowes, but check ebay for deals. ak
  8. AnalogKid

    Need help testing this circuit

    Turn over the SCR so the cathode still is connected to GND but the anode is upward. Now a DC load positions naturally between the anode and the positive rail (+9 V). The 10K resistor should go out horizontally to the SCR gate. Strongly suggested guidelines for schematic information: Power...
  9. AnalogKid

    AC load sensing

    That doesn't get you isolation from the AC line. I vote for the optocoupler. With a low cost generic opto, in its simplest form the interface is 1 resistor and 1 diode. Note that the resistor will dissipate over 2 W. You can decrease that with a capacitor rated for connection to the AC line. ak
  10. AnalogKid

    AC load sensing

    First, let's clear up the question. By "connected", do you mean connected to AC power through the switch? If yes, then an optocoupler can give you an AC-isolated square wave signal when the switch is closed, but it cannot tell you if the light has burned out. A light sensor such as a...
  11. AnalogKid

    Design of a DC voltmeter circuit

    You can reduce the zero drift by 50% or more with a couple of diodes. ak
  12. AnalogKid

    Cooling electronic circut ?

    The passenger compartment of a stopped car in the AZ or NM sun (engine off, windows up) routinely exceeds the operating temperature range in MIL-STD-810. The engine compartment is significantly cooler. ak
  13. AnalogKid

    Transistor Help

    If the transistor collector is connected to the 12 V, this will not work. If ... If ... If ... Please post your schematic. ak
  14. AnalogKid

    lm 317 tip 3055 constant current

    Not quite. The max. input-output differential voltage is 37 V. That can be sitting on 1000 V if the shunt gain set resistor is around 1.7 M. ak
  15. AnalogKid

    lm 317 tip 3055 constant current

    Not the best circuit, because the 3055 is outside the regulator control loop. So you have a regulated 317 output followed by an unregulated 3055 current booster. A couple of things ... The 3055 may start conducting at Vbe = 0.6 V, but as the collector current increases so does Vbe. Don't be...
  16. AnalogKid

    Reverse battery protection Diode

    The diode cathode is connected to the LDO input, exactly as before. When you reverse the input voltage, only those two connections are changed. Everything else is unchanged. Also, there should be decoupling capacitors from the LDO input to its GND pin. The LDO datasheet will have...
  17. AnalogKid

    Reverse battery protection Diode

    No, it isn't. When the battery is reversed, the battery positive terminal is connected to the circuit ground, and the battery negative terminal is connected to the diode anode. That is what "reversed" means. The circuit ground is defined by the nature of the circuit elements, not by any...
  18. AnalogKid

    Looking for Templates for an Analog Circuit to Control LEDs from a Photo Diode

    What are the voltage and current requirements for the LEDs? ak
  19. AnalogKid

    Need help reducing voltage

    The voltage "drop" across the resistor will vary with the current going through it, according to Ohm's Law. E = I x R The voltage across a resistance equals the value of the resistance times the current through it. So if you have a 620 ohm resistor, and the current being drawn by whatever is...
  20. AnalogKid

    timed circuits with electromagnets

    If using a CD4017 Johnson counter, no programming. What are the electromagnet coil resistance and voltage? ak
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