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  1. audioguru2

    Notch Filters and Noise Cancellers

    Hi Adam, Welcome to our forum. Why do you have electrical interference? Can't you stop the interference at its source? Or are the audio cables that connect your radio tuner to your amplifier simply not shielded? A 50Hz or 60Hz notch filter that is connected beween your tuner and the amplifier...
  2. audioguru2

    Transistor tester

    If you want the flip-flop to alternately toggle its output, then it must be clocked. The datasheet shows that the clock is pin 13, but the project's schematic has it grounded. So pin 3 of the 555 should connect to IC2's pin 13, not to pin 12. Pin 12 is IC2's reset, which should be connected to...
  3. audioguru2

    Sine wave inverter

    Hi Kevin, Please provide a link to any project that you talk about. You probably mean this inverter project: It is a square-wave inverter, not sine-wave. You could replace the opamps with transistors if you use enough of them, to provide a fairly high-current pullup and pull-down, like the...
  4. audioguru2

    Infra Red Remote control

    For the very-low-input-bias-current LM308, use a TL071. It has a FET-input. For the LM567 tone PPL/filter, use a high-Q bandpass filter circuit.
  5. audioguru2

    Infra Red Remote control

    The LM308 and LM567 were discontinued many years ago.
  6. audioguru2

    New, Nite Rider lights, Project

    Hello, I'm a newbee and I built this project and it doesn't work with a battery, but works OK with my regulated power supply. I used a 555 IC just like in its parts list. Could somebody help me pleez? Mapquest couldn't. Here come these queries! ;D
  7. audioguru2

    Flickering dimmer switch

    Hi Steve, Your dimmer switch is certainly faulty since it can't go to full brightness. If the total power of your bulbs is within the power rating of the dimmer, then the blown bulb may have caused it to fail at the moment that the bulb blew. Sometimes a light bulb will blow when you turn-on the...
  8. audioguru2

    The Meaning of PMPO?

    Hi Shahriar, PMPO means Peak Music Power Output and is a way to advertise false power numbers that are much larger than they really are. Audio power from an amplifier to a speaker is usually measured by feeding a sine-wave into the amplifier and measuring the power output into a resistor load...
  9. audioguru2

    New, Nite Rider lights, Project

    MP, All ICs in the project's parts list have CMOS part numbers, except for the standard, high-current 555. Perhaps the author doesn't know that the standard 555 draws a high switching current and is not CMOS. 8-pin DIP CMOS 555's are available at Digikey as follows: TLC555CP Texas...
  10. audioguru2

    Not your average charger!

    Man!! Did I ever get this one wrong. Of course, the sparkplug's high-voltage terminal must be connected to the antenna, and nothing else. Then the sparkplug's threads must be connected to the high-voltage terminal of the coil, and nothing else. The sparkplug is in series with the coil. So when...
  11. audioguru2

    Flickering dimmer switch

    A small capacitor across a power AC circuit won't make any difference. A larger capacitor will simply try to reduce the AC voltage and heat the capacitor and dimmer. Maybe the Diac or Triac is faulty and passes only half-wave. Are the lights still kind of dim when the dimmer is at maximum...
  12. audioguru2

    Not your average charger!

    Hi GPG, The author doesn't report charging a deep discharge (car?) battery, but just replenishing (trickle plus a bit more) the charge that was taken by a transistor (and tube, but what about the filiaments?) radio. But he has it hooked up (his words) wrong. He has the entire coil in series with...
  13. audioguru2

    New, Nite Rider lights, Project

    Hi Guys, Nice new project. Lotsa ICs. This project is here: http://www.electronics-lab.com/projects/automotive/011/index.html Automotive catagory? No wonder I couldn't find it. For those of you who build this project, I recommend adding a capacitor across the power supply, and replacing the 555...
  14. audioguru2

    What Chip Converts Decimal to Pulse ..?

    MP, No, he is not talking about DTMF, but about the IC in a telephone that can be switched between "pulse" (like rotary dial) and "tone" (DTMF). His application needs the pulse output. All dialer ICs have DTMF output, but some can also be switched to produce pulse output.
  15. audioguru2

    voltage controlled oscillators

    Hi Luzell, You can use just the VCO part of the complicated phase-locked-loop tutorial that MP posted. Instead of the additional phase-locked-loop parts, you can use a simple variable DC control voltage from a pot that I recommended to set its frequency to 10KHz.
  16. audioguru2

    Not your average charger!

    Hi Ante, That's a unique way to use an ignition system in reverse, complete with a functioning sparkplug. It may be necessary to connect the battery through a full-wave rectifier, because I think that the antenna will pickup a lot of RF, and the polarity of the static charge may depend on "which...
  17. audioguru2

    Anything Reasonable other than Drilling?

    Hi Mhz, Have you tried Veroboard (also called stripboard)? All holes are already punched and half the printed wiring is already done. The rest of the wiring is done with jumpers, all in the same direction. Epoxy-fiberglass substrate is available. The strips are cut with a simple hand-cutter (to...
  18. audioguru2

    a dual powered calculator

    Hi Ruge, Welcome to our forum. A calculator's solar/battery supply probably uses a simple two-diodes OR gate. Each diode feeds the calculator's supply, with the solar cell at one diode and the battery at the other. The source with the highest voltage forward-conducts through its diode and the...
  19. audioguru2

    help, help, help, it's too hot

    Thanks, GPG, That compensation IC will allow extreme accuracy. I just look at the colour of my fingers, err metal, that is being heated.
  20. audioguru2

    help, help, help, it's too hot

    Hi Harsh, As for your two cents, the reference table that Ante posted shows that a J thermocouple that is generating 69.55mV is at 1200 degrees C! That's hot enough to burn down your "shack", their thermistors and everything else that's there. Isn't that the thermocouple that is directly in the...
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