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  1. WHONOES

    What specs are the most important when swapping transistors with another type?

    To see if the amp is oscillating, the best place to monitor is at the amplifier output terminal with you speaker connected. If there are fundamental differences between the two designs as you seem to indicate then, the circuit provided is of limited use. The compensation in modern amps is...
  2. WHONOES

    4 kW DC excited synchronous motor

    Fair enough. I do know though that it is possible to get substantial voltages from car alternators.
  3. WHONOES

    Cleaning Soldering Iron Tips

    I only ever use the damp sponge. Have done so for over 40 years. Get yourself some soldering tip cleaner. This is a small tin of solder granules embedded in resin flux. You plunge the offending tip in whilst at working temperature and pretty much guarantees a clean tip even for one that is...
  4. WHONOES

    Photo sensor

    The circuit looks fairly simple. What range is the detector required to work at. As a first suggestion, look up "reflective photo interrupter". I should imagine that U1 is a comparator of some sort.
  5. WHONOES

    4 kW DC excited synchronous motor

    A car alternator would be single phase but I guess you could run 3 together but then there would be issues with phase relationship.
  6. WHONOES

    Electric skateboard

    Why don't you just fit bigger battery?
  7. WHONOES

    What specs are the most important when swapping transistors with another type?

    The higher ft (transition frequency which defines the point at which the transistor current gain becomes unity) may result in a wider open loop bandwidth. It depends on the frequency compensation applied to the circuit to keep it stable in closed loop which may be marginal or inadequate. When...
  8. WHONOES

    Design bass amplifier

    If you wanna make big bass then you need correspondingly big speaker with amps to match. Josejos:::: If you only want to make a sub bass unit, give us some idea of what you want and with what you hope to achieve it.
  9. WHONOES

    Design bass amplifier

    Is that on a single supply. If so then he needs an output capacitor to remove the DC content from the speaker. He will indeed see a fairly large offset voltage if that is the case.
  10. WHONOES

    Design bass amplifier

    AG. The output offset voltage of an amplifier is nothing to do with the waveform of the signal and is a function, primarily, of the small difference in the Vbe of the input transistors times the gain of the amplifier Calling it the output offset is a bit of a misnomer as it is actually an input...
  11. WHONOES

    Design bass amplifier

    How have you configured the thing? Are you using one amp per speaker. What sort of filters are you using? What crossover frequency? Are you still using the TDA2030?
  12. WHONOES

    Design bass amplifier

    Is the speaker rating RMS or Peak power? It makes a lot of difference.
  13. WHONOES

    Design bass amplifier

    Forgot to mention in earlier post that the conventional way to do what Josejos is after is to use 1 amplifier per speaker is 4 speakers and 4 amps and then use active filters to split the audio spectrum as required.
  14. WHONOES

    Design bass amplifier

    For all the years that I have been doing this, it has been the other way round. The amp should always be more powerful than the speakers. There is a few reasons for this. If you are running 50W speakers with a 30W amp and you try to run the amp flat out it is going to sound awful also there is a...
  15. WHONOES

    Controlling 12V battery output to heating element

    Give it a try.
  16. WHONOES

    Scooter motor to power wood lathe

    A little research shows that the motor you have presented. is a 500W O/P @ 2500 RPM brushed motor rated at 24Vdc and 26.7A at full load (from Motion Dynamics). A simple PWM circuit based on a large FET or two or three and the ubiquitous 555. It would be possible to incorporate load / speed...
  17. WHONOES

    Do SLA chargers fight if paralleled?

    The whole point of using alternators on cars instead of the old dynamo's is that they will give a useful charge from relatively low RPM. If using a car alternator, you will need enough energy in the battery you are charging to power the armature (that's how they work). The current into the...
  18. WHONOES

    Controlling 12V battery output to heating element

    If you want to try and build your own controller, you could try the attached circuit for a very simple 555 pwm controller. A version of it has appeared elsewhere on this forum. The transistor will need to be mounted to a small heat sink.
  19. WHONOES

    Controlling 12V battery output to heating element

    How much current does it draw?
  20. WHONOES

    Beginning electronics, understanding whats actually happening

    Chuckle worthy.
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