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  1. audioguru2

    motor driver L298 help

    4QD will give you some of their secret circuitry info if you pay for their subscription.
  2. audioguru2

    Oscilloscope

    That 'scope kit is the cheapest that I have seen for more than 40 years. It has only a single channel. Most 'scopes have two so you can compare signals, pulses and their timing. It has a pretty small screen but is OK for a hobbiest. It has a low bandwidth but is OK for a hobbiest. It is about...
  3. audioguru2

    Dual 741 / 747 modern upgrade

    An 8-pin package doesn't have enough pins for offset-nulling. Add your own offset-adjustment circuit to any dual opamp. Or buy a modern dual opamp that has laser-trimming for an extremely low offset voltage. Sorry, I don't know their numbers.
  4. audioguru2

    Infrared Receiver

    Good. Yes. Each IR pulse turns on the darlington transistor so its emitter rises to +4V max, then the lower end of the LED would rise to +2.2V or less. A DC meter would measure half which is 1.1V or less. Your LED is missing its cathode line and is drawn backwards. You have a highpass filter...
  5. audioguru2

    Mini project (Help me)

    Did you study any electronics in high school or in university? Ask your teacher to explain more details about the project: 1) Two decades of what-  frequency? 2) Cascaded what- bjt's or opamps? 3) Is an "aplifier" an amplifier?
  6. audioguru2

    transformer problem

    You don't make sense. A transformer with a 15kVA rating can power a 15,000W load and will be huge. A transformer for a neon sign that hangs in a window is 220V/15kV/10mA and is rated at 150VA. It is the size of a shoe box. 
  7. audioguru2

    motor driver L298 help

    Hi Ante, Here is the PWM tutorial from the DC motor speed controller manufacturer for golf carts and wheelchairs: http://www.4qdtec.com/pwm-01.html They talk about the circuits that they and their competitors tried, then better ones.
  8. audioguru2

    What si that series resistor with Diode in and Inductor Switch circuit?

    A relay without a flyback diode releases immediately when its current is stopped. I have read that when a flyback diode is connected without a series resistor then the current circulates and the release is delayed. Adding a resistor in series with the diode is half-way between the two...
  9. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    The voltage reference circuit can be re-wired to use the TL431 precision IC instead of a " non-presision, non-temperature compensated zener" like this:
  10. audioguru2

    What si that series resistor with Diode in and Inductor Switch circuit?

  11. audioguru2

    Battery current

    Hi Prateek, Little batteries or wall-wart AC-DC adapters cannot give "any" amount of current because they have an internal resistance that limits the max current. The more current that is drawn then the lower becomes the voltage. A new little 9V alkaline battery can give about 500mA to a short...
  12. audioguru2

    project help with toy IC boards

    With a 9V supply (a brand new battery), an LM386 can provide 450mW of power to an 8 ohm speaker with low distortion. If the volume control is turned up higher or if the input signal becomes louder then the output will clip and become very distorted for the louder parts that are clipped off. Just...
  13. audioguru2

    motor driver L298 help

    MP. You don't control the speed of a DC motor by the frequency of square-wave pulses that are fed to it. The speed is controlled by the duty-cycle of the pulses which is PWM. The guy in the tutorial showed how a cheap motor created huge current spikes. It looks like its brushes short together...
  14. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi Trigger, The Hammond 182R30 has two completely separate 30V secondary windings. Each winding can power one of these 0-30V/5A power supply projects and you can connect the regulated outputs of the projects in series for up to 60V output.
  15. audioguru2

    What si that series resistor with Diode in and Inductor Switch circuit?

    Catch diode, protection diode, flyback diode, freewheeling diode. Lots of names for the same thing.
  16. audioguru2

    Creating/making Music ICs

    Look at Melody IC in Google. There are some with songs in them or with tones that you can play. There are some that you can use to record sounds. They are simple and cheap so the quality of the sound is poor.
  17. audioguru2

    Creating/making Music ICs

    You cannot reprogram the music of a cheap IC on a birthday card or toy. It is made with the music on it. There are some ICs available somewhere that you can record a few seconds of sounds. A ucontroller could be programmed to use its memory to record some sounds.
  18. audioguru2

    Creating/making Music ICs

    What is a music IC? Give us a part number or a datasheet. Its datasheet will say how to program it.
  19. audioguru2

    amplify..

    It looks like the relays are wired to allow the motors to reverse direction. There is nothing on the schematic to turn the motors off.
  20. audioguru2

    motor driver L298 help

    No MP, The "enable" inputs of the L298 are used to turn it on and off with PWM pulses to control the speed of a DC motor. The inputs need very low current so work with TTL or microcontroller logic levels. Of course the L298 is needed if you are using PWM to control the speed of a DC motor. The...
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