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  1. Audioguru

    Momentary Switch to directional DC motor

    Here is a very simple "alternate action" circuit. Push the button and the output goes low. Push the button again and the output goes high. Push it again and the output goes low again, over and over if you want. this circuit can control a power h-bridge that drives the motor forwards or reverse.
  2. Audioguru

    Where to find 4" 16 ohm speaker?

    Parts on ebay that are "unbranded" are parts made by somebody who never made those parts work properly??
  3. Audioguru

    Where to find 4" 16 ohm speaker?

    I looked for a 4", 16 ohm speaker at Parts Express. A 2W speaker is very cheap with poor sound. 16 ohm speakers were used many years ago, not today. If you use a modern 8 ohm speaker with an 8 ohm resistor in series with it to prevent the amplifier from exploding then it will not be as loud as...
  4. Audioguru

    When replacing battery in a pack

    I would never buy cheap Chinese junk from ebay, AliExpress or Amazon. I buy most Name Brand electronic parts from Digikey or Newark where datasheets are available first.
  5. Audioguru

    When replacing battery in a pack

    Here are cheap batteries that people are buying on ebay:
  6. Audioguru

    How to design a transistor circuit that controls low-power devices

    1) He wants to turn on a 12VDC motor from a 12V "control" but he does not say what is the maximum allowed control current so maybe he should use a mechanical switch or a simple piece of wire. 2) He posted a video that wrongly talks about a PN2222A transistor with a hFE of 100 but its datasheet...
  7. Audioguru

    How to design a transistor circuit that controls low-power devices

    Amazon sells cheap clothing and shoes. They know nothing about electronic parts. Bridgold is an unknown Chinese company who might sell fake or defective electronic parts. Anybody can write a good rating including the owner and friends of the Amazon seller who sells cheap junk. Why are you using...
  8. Audioguru

    How to design a transistor circuit that controls low-power devices

    Why do you wrongly guess? Look at the datasheet of a TIP31 medium power transistor. Its datasheet shows the order of its pins and all its spec's including the base current needed when saturated. The starting current of the motor might burn out a 3A TIP31 so maybe a 6A TIP41 is needed. Look at...
  9. Audioguru

    How to design a transistor circuit that controls low-power devices

    Please proof-read what you write. 200 Watts is how much POWER (heating) a resistor can survive. A 200W resistor will be huge, heavy and expensive. Your 200 ohms resistor will have a power of (8.3V squared)/200 ohms= 0.34W. Use an inexpensive little 1/2 Watts resistor.
  10. Audioguru

    How to design a transistor circuit that controls low-power devices

    Beta is used when a transistor always has plenty of collector to emitter voltage like in an amplifier. But you probably want the transistor to fully turn on when it is saturated. Then you should see on the datasheet its "saturation Vce voltage loss" which is always when its base current is...
  11. Audioguru

    DIY Amplifier not working, speaker makes popping sound, not sure what is wrong?

    The datasheet of the LM386 amplifier IC shows that its output power into an 8 ohm speaker when the power supply is 9V is only 0.4W at low distortion. 0.4W is not loud. Why do you think changing the speaker will increase the output power? Oh, if the speaker is only 1" in diameter then it...
  12. Audioguru

    Max Ratings L298N - V*A!=W?

    Without seeing the spec's for your motor I simply guessed how much current it draws when it starts running. How much is the current when you slam it suddenly at full power in the other direction? Double the stalled current? Is the braking action of the circuit not wanted?
  13. Audioguru

    Max Ratings L298N - V*A!=W?

    Complementary Mosfets are common in H-bridge motor reversing circuits. Your Mosfet polarity descriptions are backwards. Here is an H-bridge circuit using complementary Mosfets. When one transistor is turned on then the motor runs forwards. When the other transistor is turned on then the motor...
  14. Audioguru

    Max Ratings L298N - V*A!=W?

    If a motor draws a max current of 2A when running at full speed then it might draw 5A or 8A when it starts from a stop Then paralleling a few drivers is needed. If your supply is 12V and one driver produces a 2V saturation voltage loss then the motor gets only 10V and probably will not run at...
  15. Audioguru

    Stumped on this circuit blinking led with 1 transistor

    Is an "LED Flahser" An LED that blinks with a hiccup?;)
  16. Audioguru

    DIY Amplifier not working, speaker makes popping sound, not sure what is wrong?

    The amplifier has a volume control and a gain control so the input signal level can easily be reduced.
  17. Audioguru

    DIY Amplifier not working, speaker makes popping sound, not sure what is wrong?

    I think your 9V battery is weak. Try a new one. EDIT: Of course the amplifier produces distortion if the volume is turned up higher than about 0.4W of output which is about like a cheap clock radio.
  18. Audioguru

    6v LED brighter with 3v battery

    I have a small flashlight given to me at a politician's park BBQ. It had one white LED and was fairly bright to see a lock for a key to enter. The flashlight got dimmer then quit. Inside was two tiny (coin) CR1220 3V Lithium cells in series and no current-limiting resistor. So it used 3V to...
  19. Audioguru

    Stumped on this circuit blinking led with 1 transistor

    Absolutely not! Why does every little transistor have a maximum emitter-base reverse voltage of only 5 or 6V? Because a higher voltage will cause avalanche breakdown. Why is the transistor connected backwards (reverse biased emitter-base)? So that it has avalanche breakdown to blink the LED...
  20. Audioguru

    Is transistor faulty or something else amiss

    In my first post in this thread I said all the problems of this extremely simple circuit and how I fixed them.
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