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  1. Audioguru

    the prettyLow Drain Flasher circuit with BJT

    Can't you see that the polarity of the 47uF capacitor is backwards?
  2. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    The transistor datasheet shows how much the chip temperature rises with power dissipation and the datasheet of a heatsink shows how much is the temperature rise of its transistor mounting surface with power dissipation. Add about 0.5 to 1 degree C rise per Watt when an insulator is used between...
  3. Audioguru

    Capacitor between collector and emitter help

    Because they did not learn the basics of electronics. I am not a doctor because I never learned the basics of medicine and diseases but I do not put medical errors on the internet like some "quack" wannabee doctors do. There are even people who know nothing about mechanics putting errors about...
  4. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    You might need a high power and noisy "leaf blower" to cool that little heatsink.
  5. Audioguru

    Homemade automatic plant waterer

    I made a circuit that lights an LED when a plant becomes dry. But pure water does not conduct, fertilizer or salts in water causes some conduction and my tap water conducts a lot. Your probes should use AC because DC causes plating and corrosion.
  6. Audioguru

    Help, audio mixer!!

    I agree that the transistor is biased wrong, it is almost cutoff. Each 47k resistor feeding the input resistance of the transistor and its bias resistors reduces the level to 1/11th. Then the voltage gain of the transistor will be about 180/11= 16.4 times. A mic usually needs a gain of 100 to 200.
  7. Audioguru

    What charger to use for LI-ion batteries

    My 18650 Lithium Ion cells from a laptop are name-brand (Panasonic) and are rated at 3000mAh (3A). I adjusted an LM317 regulator to an output of 9.1V and it has a 1N4002 rectifier diode in series with its output so that the circuit output is 8.4V. It is powered from a 12VDC/1A wall wart. Two of...
  8. Audioguru

    Sick of my breadboard! quality breadboard recommendations please.

    I gave up using a solderless breadboard 42 years ago and have used a compact and soldered stripboard ever since. Most of my many projects at work were custom and only one prototype was made and sold as the finished item. They looked like a pcb. Here is my FM transmitter:
  9. Audioguru

    Capacitor between collector and emitter help

    Somebody else found the circuit of an FM transmitter on the internet, built it and asked on a forum why it didn't work. I looked at its circuit and saw 4 errors that I fixed: 1) Its mic preamp transistor was biased wrong when the battery was new and again when the battery was old so I corrected...
  10. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    I hope your heatsink has fins because usually the driver transistor and bridge rectifier have their own heatsinks. I am glad that you are using a fan.
  11. Audioguru

    Capacitor between collector and emitter help

    I see how it can be a simple AM crystal radio. The website for Swagatam Innovations is www.homemade-circuits.com in India. I could not find this project in their list of hundreds of circuits.
  12. Audioguru

    Capacitor between collector and emitter help

    There are some real teachers who come to these forums and there are some wannabe teachers. Sorry, I am not a teacher. Also, you posted a horrible schematic that will not work because it is full of errors.
  13. Audioguru

    Capacitor between collector and emitter help

    This is not a school. On this website and others we already learned electronics in school, university or college. We do not come here to teach people like you who know nothing about electronics, instead we come here to chat with people like us about how circuits work and how to make them simpler...
  14. Audioguru

    Capacitor between collector and emitter help

    An earphone should never have DC current in it. You must learn about basic electronics to calculate capacitor values. It looks like Swagatam Innovations in India also knows nothing about electronics.
  15. Audioguru

    Button to button circuit

    I think the light is a high power searchlight and the horn is the high current one from a fire truck. Then the engine has no spark when both are turned on. No battery?
  16. Audioguru

    Button to button circuit

    Maybe rectifier is needed because maybe the bike has an alternator and the light is an LED?
  17. Audioguru

    Comparator - Battery Cutoff

    The 1N4728A zener diode is 3.3V only when it has a whopping 76mA(!) of current in it that will quickly kill the battery. There are many 3.3V zener diodes available that draw only 5mA. This is a horrible faulty circuit. On another thread or another website there is a 3 pins IC that draws a very...
  18. Audioguru

    Capacitor between collector and emitter help

    Your circuit has the emitter of the transistor connected to the circuit's ground, then the emitter is not an input. If you connect a resistor in series with the emitter and ground then the circuit will be an audio oscillator, not a radio. But the earphone might have a resistance too low then...
  19. Audioguru

    Capacitor between collector and emitter help

    A common base transistor amplifier has its input at the low impedance emitter and its output at the collector. It oscillates if a capacitor feeds some collector signal to the emitter..
  20. Audioguru

    Designing Circuit by BC546

    The parts were selected at random without any circuit design.
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