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  1. audioguru2

    Passive audio filters

    Hi Vainajala, What are those curves? The top one couldn't be for the speaker's phase. The bottom one couldn't be for frequency response, but maybe for group delay.
  2. audioguru2

    Pulse Width Modulation DC Motor Control

    Hi Ante, Does your simulator have a 74C00? Or 4001, 74C02, 4069, 74C04. They will all work the same way in this circuit.
  3. audioguru2

    Smartkit order

    Hey, there's a distributor just a short drive from me. I don't like those kits. They seem to have mistakes, like our 0V to 30V, 3A adjustable power supply project. I had a quick look at their kits and found an amp with a dot missing on its schematic, where C3 and C8 should connect to C1 and...
  4. audioguru2

    ultrasonic mosquitoes repeller

    Hi Dazza, Thanks for posting your circuit. Do they still make unijunction transistors? I haven't seen one for nearly 40 years! I worry about how little sound output that an ordinary loudspeaker will produce at 22KHz. Most expensive hi-fi tweeters have difficulty reaching 20KHz. The impedance of...
  5. audioguru2

    Electronic Stethoscope

    Hi RG, Welcome to our forum, You are certainly not the only one with your problem. Just read this post and the one on the author's web-site. This project's schematic and parts list have errors. A simple dot on the schematic fixes the noise problem (where certain parts should be connected...
  6. audioguru2

    My Avitar

    Can you post a whole bunch of them? I want to exercise my video card. Make them all out of sequence. It looks cool that way on my thumbnail viewer. Try it.
  7. audioguru2

    Push button Selector Switch for 6 LED

    Hi Epodandy, Welcome to our forum. You could use a CD4017 or CD74HC4017 (higher output current)stepper to select the LEDs, and a monostable circuit to de-bounce the button. But it will need a step-up voltage converter to light 3.5V or more blue, white or purple LEDs from only 3VDC. Yes, purple...
  8. audioguru2

    Electronic parasite zappers

    Hi Steven, What a lot of oscillators! They are going to put doctors, drug companies and even Viagra out of business. I think that I met Kubota, he's a cool dude.
  9. audioguru2

    The LM317 Calculator

    MP. You are correct, load current for an LM317 is from its output to ground. But so is the current through R1 plus R2, which become, you know, its load. Most of the many circuits that you posted have a permanent load with a current far exceeding the minimum load current requirement, especially...
  10. audioguru2

    My Avitar

    Hi John, As soon as I saw your new hat, I knew that it was you under it.
  11. audioguru2

    Infrared Light

    Hi Electropank, Welcome to our forum. Anything that is hot radiates infrared energy. The sun, a fire, an electrical heater and even living mammals give off infrared energy. What are you making that requires you to flood an area with infrared "light"?
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Dkilshaw, Here is a current source circuit for you that will allow this project to have an output voltage that is 1V per 1K ohms. The way that it works is that the opamp will make certain that there is 5.6V across the 15K resistor. Therefore the current through the 15K resistor is also the...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Dkilshaw, Of course your decade box produced unlinear output, it needs a constant current source to be linear. The output of U1 is a constant voltage source. You could add a constant current source made from another opamp and a PNP transistor or P-channel FET to feed your decade box. For 1K...
  14. audioguru2

    switching circuit

    Hi Ante, I think that it would be difficult to make an analogue peak detector since the peak value will change depending on the temperature of the battery and its internal resistance, etc. It needs to be done dynamically, using sample-and-hold. Even a sample-and-hold is difficult to make for a...
  15. audioguru2

    The LM317 Calculator

    Hi Suraj, I do see your point with the calculator article. If you enter the desired output voltage, it won't calculate the value of R2, which is what is needed. In my "easy" calculation for a 12V output, I made a mistake with my numbers and ended up with a wrong value for R2. I discovered my...
  16. audioguru2

    The LM317 Calculator

    MP, National Semi. rates the Minimum Load Current for their LM317 as 10mA, so why don't you believe them? The very low Adjustment Pin Current has nothing to do with it. That current is so low because this regulator transfers all of its operating current to the load. The expensive LM117 simply...
  17. audioguru2

    Pulse Width Modulation DC Motor Control

    Hi Ante, I don't know what's wrong with your simulator, but I have seen many oscillators like this, and Pin 4 of the CD4011 should be swinging from 0V to +6V with about a 50% duty-cycle. Since the gate threshold of the IRF511 is typically 3V, it should supply pulses of about 2A. Don't turn the...
  18. audioguru2

    The LM317 Calculator

    Hi Suraj, Why do you need a calculator, especially one with a serious error like that one, when the resistor calculation with numbers is so easy? The datasheet for the LM317 is here: http://www.national.com/ds/LM/LM117.pdf Page 1 shows a typical circuit that is exactly the same as our Calculator...
  19. audioguru2

    Inside a TO-3 Transistor case

    Photodiodes can also be used as current generators for fast response. You can identify this circuit when the photodiode is directly connected to the inverting input of an opamp that also has a feedback resistor. Usually, photodiodes are reversed-biased with a resistor, and light (or IR energy)...
  20. audioguru2

    Pulse Width Modulation DC Motor Control

    Hello, I have been researching circuits for PWM speed control of DC motors and found our project here: http://www.electronics-lab.com/projects/motor_light/033/index.html Has anybody tried it? What does it do? It appears to be a simple adjustable-frequency "Classic" 2-inverter CMOS oscillator...
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