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  1. Audioguru

    Ferrite rod antenna explanation

    I am glad you fixed the wiring problem on the breadboard. Breadboards cause many problems. A normal radio has at least 5 tuned LC circuits to tune in the station you want but reject interference from all the other AM radio stations. This simple radio has only a single LC tuned circuit so it must...
  2. Audioguru

    Wiring 5v to a 12v powersupply

    A resistor is not a voltage regulator. You were told to use a 5V regulator that will probably cost more than a 5V 0.8A PSU. The 5V from USB is regulated, but many PSU's are not regulated and might blow up your USB powered device.
  3. Audioguru

    Ferrite rod antenna explanation

    Try increasing the value of R14 by 20% to 56k and reducing the value of R1 to 820. But a 10% change to 51k and 910 might work better. Maybe R14 needs to be 68k and R1 be 680.
  4. Audioguru

    Ferrite rod antenna explanation

    He made his own amplifier that is awful with no negative feedback. ALL audio amplifiers have negative feedback, but not the simple one he designed. A simple regenerative circuit makes an extremely poor radio that produces a lot of noise. I think yours begins to oscillate when you turn up the...
  5. Audioguru

    Switch

    A balanced microphone has two audio wires and a shield wire. You use a DPDT switch to switch both wires. An unbalanced mic has only one audio wire that needs only one pole of a switch so a SPDT or DPDT switch can be used. A schematic for this switch is extremely simple:
  6. Audioguru

    Ferrite rod antenna explanation

    I saw the video of the Choccy Block radio and it played a lot of noise and distortion. Its audio power amplifier is awful because it has zero negative feedback. The datasheet for the LM386 shows how it should be connected and it has built-in negative feedback for very low distortion. I have...
  7. Audioguru

    FM fading

    Your antenna must be 'broadside" toward the radio station's location or the location of its signal reflection. Get the radio station from the internet instead.
  8. Audioguru

    Switch

    You did not say if the microphones are balanced or unbalanced. Connect the cable shields all together and if the mics are balanced then switch both their audio wires and if unbalanced then switch only the single audio wire.
  9. Audioguru

    Simple FM Radio receiver

    it is not a Superregen, it is an ordinary regenerative radio that produces very poor performance. It actually detects AM and all the interference on AM. It is tuned to one side of an FM station to produce FM detection using slope detection.
  10. Audioguru

    Replace variable capacitor with varicap

    I see a few problems with the LM386:
  11. Audioguru

    Gcse project NEED HELP

    The OP said he has to do a "dt" project for GCSE and I found out that GCSE in the UK is equivalent to grade 11 high school in Canada where grade 12 is the final high school year. But what is "dt"? Is "dt" a Design and Technology course? Then he selects a project himself? The university project...
  12. Audioguru

    Gcse project NEED HELP

    It seems that this student has a teacher who is paid to teach the basics but didn't. Why can't the student ask the teacher to explain the basics? Does the teacher expect the student to find out things on the internet?
  13. Audioguru

    Gcse project NEED HELP

    We do not have GCSE in North America but since this project is extremely simple then it must be for little kids who are only 10 years old or younger, or you were taught nothing about electronics. it should be obvious that the resistor value is simply calculated with Ohm's Law and a little bit...
  14. Audioguru

    Ferrite rod antenna explanation

    Test the audio amplifier with an audio input signal. You did not post the corrected schematic for the "radio" or for the LM386 amplifier so we cannot help you fix them. Also please post photos of the radio and amplifier you built.
  15. Audioguru

    Ferrite rod antenna explanation

    Do not use a breadboard for an LM386 because the capacitance between the many rows of contacts and wires will probably cause it to oscillate at a radio frequency and get hot. When it is oscillating then it cannot amplify audio. Solder the LM386 and its capacitors on a compact stripboard or pcb...
  16. Audioguru

    Ferrite rod antenna explanation

    I doubt that maze of wires on a solderless breadboard will work like a radio. Like most IC audio power amplifiers, the LM386 has a frequency response higher than 1 megahertz so it will probably oscillate like mad when connected on a solderless breadboard with the capacitance between all the rows...
  17. Audioguru

    Ferrite rod antenna explanation

    You can build this lousy, wrongly designed circuit then fix its problems one-by-one like I did with the FM transmitter that I fixed its 4 problems. 1) Make a Super-regen that adjusts its regen amount by itself instead of this ordinary regen that you must fiddle with its regen control. 2)...
  18. Audioguru

    Ferrite rod antenna explanation

    No, you typed the numbers backwards, the power amplifier is an LM386. My post mentioned all the other problems that you have with that poorly designed circuit.
  19. Audioguru

    Ferrite rod antenna explanation

    You show a TL081 opamp with its (+) input connected through R6 to its negative supply that is 0V then it is not biased [properly. Then it will do nothing because its inputs MUST NOT be within 4V from either supply voltage (the datasheet says so as its Common Mode Input Voltage Range). What is...
  20. Audioguru

    Digital music player with a Tivoli Audio Model One

    The Texas Instruments amplifier in your link is modern with a class-H voltage boosting feature, so that its max output power is much higher than a normal older amplifier. Its package is so tiny that it has BALLS (!!) instead of pins and will be impossible to solder unless maybe it is soldered in...
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