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  1. dorke

    Night detector power LED (with LDR)

    Welcome to EP. The BC557 is a 100mA transistor,do you think it will not break at 300mA? Get a bigger transistor!!! What LDR are you using?
  2. dorke

    Need to Figure out if this Spectrum Analyzer Works

    Looks like it is working. The base line looks a bit high 1. Set the center frequency to 54MHz. 2. Set the Span /div to 1Mhz. 3. You should have the cal signal in the center of the screen with an amplitude of -40dBm. What do you ?
  3. dorke

    Led light bar

    You can add another IC to get 10 bits ,not a problem. Would a "volume knob" instead of the switches be o.k?
  4. dorke

    Led light bar

    A universal shift register should do the job for you. If you had used only 8 LEDs the 74HC299 would be a perfect choice. One side input is permanently shifting in "1"s , the other is permanently shifting in "0". You will control the direction of the shift with S0,S1 lines(via switches). And...
  5. dorke

    Drop voltage on transistor base

    Try measuring the on/off voltages on the junction of R1 and D1. What led is 12V? Another problem is ground reference between the 12V battery and the UPS. Please show it on your drawing.
  6. dorke

    Drop voltage on transistor base

    The obvious problem is the 12v supply is connected in the opposite direction. Change it and recheck ,like so:
  7. dorke

    Temperature Measurment

    Are you referring to the Anode plate of a vacuum tube? Maybe with a IR laser thermometer?
  8. dorke

    Low-ESR 1uF electrolytic (hard to find)

    In general, for HiFi Audio,both electrolytics and tantalums are a poor choice for the signal path . The better solution is to use polyester/mayler capacitors types. In your case the vocoder compresses voice,degrading it's quality any ways,so it is most probably not important. Since your...
  9. dorke

    Low-ESR 1uF electrolytic (hard to find)

    The application is a Vocoder. i.e. audio is degraded anyways. That is why they allow themselves the use of tantalum caps in the audio path. It isn't recommended in HiFi audio, because of the poor behavior of tantalum's behind very low frequency audio (bass+) ,polyester caps are to be used...
  10. dorke

    Calculating Resistance With Just Voltages? Basic DC Circuit Design

    The Arduino UNO can be easily operated from 12V,hence you don't need the 10v regulator. Drive the all thing from a 12v dc source. Drop the voltage to the motors with a 5v regulator. In fact the 28BYJ-48 motors can be operated at 12V as well ! So you can power the all thing from a single 12V...
  11. dorke

    Calculating Resistance With Just Voltages? Basic DC Circuit Design

    The purpose of a voltage regulator is to provide a fixed and stable voltage at it's output. Putting a series resistor with the load will oppose this: the voltage to the load will be dependent on the load current.
  12. dorke

    Low-ESR 1uF electrolytic (hard to find)

    It is strange,you see, tantalum capacitors aren't usually used in audio circuits. Maybe you are confusing them with polyester caps. or such. A photo may help.
  13. dorke

    Line tester

    Actually circuit is closing. Like duke noted, it's the capacitance of your body and boots to the earth ground, the close the loop when testing mains line. I would add that the neon bulb in your tester requires very little current to light-up.
  14. dorke

    Calculating Resistance With Just Voltages? Basic DC Circuit Design

    You do not need 24V to operate this . Dropping 24v to 5V is very wasteful of energy, and will create unwanted heat in the regulators. 12V should be enough. 1. You can connect the 12v directly to the pump. 2. 10V controller? sounds like a strange animal...Have any datasheet? Are you sure...
  15. dorke

    SCADA

    If possible, Ask to make an actual visit to the water treatment plant, and talk to some technician there. Sending you to school makes things clear.
  16. dorke

    SCADA

    "Its about a 3 year commitment"? What kind of commitment? Military service? Overseas? You should check very carefully what is involved,the working conditions,contract ,disengagement etc.
  17. dorke

    Circuit board wire connectors question

    It can be done easily for a bit longer wires . For longer distances,you need to know what are those wires carrying. What is the distance you need?
  18. dorke

    SCADA

    Well, probably maintain/repair/operate/program a Scada system ?
  19. dorke

    Add BLUETOOTH to an old radio

    The way that guy does this is very cumbersome. You can use one of those gizmos and save yourself a lot of trouble. It can be powered by the most common USB charger. It requires you to add a line- in input to your radio. That isn't complicated,especially if you are willing to do it instead of...
  20. dorke

    A question about electrical Theory

    O.K that can be. As we say: "A picture is worth a thousand words". Easier now?
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