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  1. Audioguru

    5v from 12v is this viable?

    Now both of the LM386 amplifiers will overheat and melt. 10 or 15 years ago there were 76 bridged car radio amplifier ICs available but today there are only a few left. They have a metal tab for a heatsink to be bolted on and deliver 14 clean Watts to a 4 ohm speaker. You 12V to 5V transistor...
  2. Audioguru

    Why don't I get a Sine wave?

    Thank You. The original schematic was a mess with power supply wires and oscilloscope wires all over the place and had so many errors that at first I did not want to bother with it. Then I thought I might simulate it to see if when it is fixed the output roughly resembles a sinewave but I did...
  3. Audioguru

    Why don't I get a Sine wave?

    I copied then corrected the original circuit:
  4. Audioguru

    5v from 12v is this viable?

    The stuff on the left side is supposed to be a 12V to 5V regulator to power the Bluetooth dongle but the 100k resistor barely powers the zener diode with no current for the transistor. Try 680 ohms. The datasheet of the LM386 shows it getting very hot driving a 16 ohm and 32 ohm speaker with a...
  5. Audioguru

    5v from 12v is this viable?

    Your poor little LM386 low power amplifier IC will smoke and burn if you try to have it drive a 4 ohm speaker loudly from a 13.8V supply in a car. It will overheat with only a 10V supply and a 4 ohm speaker but it will produce mostly heat but only a little output power. The LM386 is designed to...
  6. Audioguru

    What power adapter is best for 300x WS2811 LEDs on a t1000S controller?

    Without any detailed spec's you do not know how much current that one LED string (not LED strip) will pass so we must assume only one string of 50 LEDs. We also assume 60mA per LED when all 3 colors are at full brightness. I have never seen LEDs packaged each with a full size controller IC on a...
  7. Audioguru

    LED path WS2811

    When I researched WS2811 I found it to be an IC that is used on an RGB LED strip. I found improved LED strips with a WS2812B inside each LED, then each LED can be addressed and controlled..
  8. Audioguru

    What power adapter is best for 300x WS2811 LEDs on a t1000S controller?

    The current used by the LEDs depends if all 3 colors are lighted (lit?) and how bright they are. An overloaded AC/DC adapter will burn out if the continuous current is much higher than its rating. I looked in Google for WS2811 LED strips and found many manufacturers. Which manufacturer made yours?
  9. Audioguru

    LED path WS2811

    I answered you or another student in your class a few minutes ago on another website forum: "LED strips are powered from a 12VDC controller, not from a 12VAC transformer. You said, "we". If it is school work then ask your teacher about it." ledstrips8.com have LED strips with a new WS2812B IC...
  10. Audioguru

    What power adapter is best for 300x WS2811 LEDs on a t1000S controller?

    I see that ledstrips8.com has strips of RGB LEDs that have a WS2812B IC built into each LED. The WS2811 was an IC that was external to the LEDs. The WS2812B is improved and can address and control each LED individually.. The maximum length is 4 meters (60 LEDs) but they say that longer strips...
  11. Audioguru

    why connect a jfet gate to source?

    The datasheet for the 2N5457 shows its IDSS (current when gate is shorted to source) as from 1mA for some of them to 5mA for some of them without a load. The datasheet also shows higher currents from 2N5458 and 2N5459. The power supply voltage does not affect the current much, down to a few volts.
  12. Audioguru

    OK To Reverse One of Two Batteries To Prevent Leakage?

    New Energizer, Duracell and a Japanese manufacturer of Eneloop (Sanyo/Panasonic) Ni-MH batteries made in the last few of years hold a charge for one year and come pre-charged.
  13. Audioguru

    reasons why frequency shows difference in three devices

    Yes, the audio modulation changes the transistor's capacitance up and down producing FM. The modulation also causes AM but an FM radio ignores it.
  14. Audioguru

    Ni-MH charging circuit query

    The battery heats and increases its internal pressure when it continues over-charging. A trickle charge after it is fully charged is supposed to be limited to 1/40th its mAh rating. The charger is supposed to detect a full charge then shut off or switch to a low current trickle charge. I think...
  15. Audioguru

    reasons why frequency shows difference in three devices

    C4 bypasses R5 at high audio frequencies boosting them for pre-emphasis. C4 changes value in different parts of the world because the pre-emphasis is different. As Davenn said, R8 biases the RF amplifier transistor Q3 and C12 couples the RF, they have nothing to do with audio. My assembly is...
  16. Audioguru

    reasons why frequency shows difference in three devices

    I fixed a circuit that did not work and I soldered it compactly on stripboard. It has a 5V low dropout voltage regulator for the mic preamp and RF oscillator and it has pre-emphasis like all FM radio stations have so it sounds great. Its range to my very sensitive hifi stereo and car radio is...
  17. Audioguru

    Headphones from amp speaker wires

    I asked abut the impedance of your headphones because some are 8 ohms and others are 600 ohms. Most are 32 ohms and 40 ohms is almost the same. 45 real Watts into 4 ohms is 13.4V. A 220 ohm resistor in series with both 32 ohms earphones in parallel causes 0.71W in the 220 ohm resistor at full...
  18. Audioguru

    Contact Cleaner?

    Music shops sell Deoxit (I think it is called) that is used for cleaning the variable resistor volume controls and switch contacts in old geetar (rock and roll) amplifiers.
  19. Audioguru

    reasons why frequency shows difference in three devices

    I think it is Multisim (<text>, <text>, <text>) that makes wires on a schematic go every which way instead of straight to where they need to go. The schematic is also hard to read because it was saved as a fuzzy JPG instead of as a very clear PNG file type and it has that awful dark background...
  20. Audioguru

    Headphones from amp speaker wires

    How can the fairly high resistance of a volume control on headphones damage a modern solid state amplifier? If you do not attenuate the high output level from the amplifier then the volume control and/or the headphones will be destroyed. The headphones jack on an amplifier is always fed from a...
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