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  1. audioguru2

    Low-pass Filter?

    Hi Hericlj, Sorry, I didn't read the part where you did not connect a transformer. All the transistors are powered by the transformer. Therefore without the transformer, the collectors of the transistors do nothing.
  2. audioguru2

    3V LED Chaser project

    Hi Newman, Welcome to our forum. ;D Try www.farnell.com and click on your down-under flag. They carry a lot more electronic parts than Dick Smith.
  3. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The efficiency is very high, maybe 95% with good Mosfets: 1) One Mosfet is on. 2) Both Mosfets are off. 3) The 2nd Mosfet is on. 4) Both Mosfets are off. Repeat. When a Mosfet is on then it has a very low voltage across it so its wasted power is low. When both Mosfets are off then no power is...
  4. audioguru2

    22 W Audio Amplifier

    The TDA1554 has 4 power amplifiers inside. It can be used as 4 amplifiers or as 2 bridged amplifiers. An ordinary amplifier drives one end of a speaker and the other end is grounded. The speaker gets the supply voltage less losses as its peak-to-peak voltage. A bridged amplifier is two...
  5. audioguru2

    Audioguru FM Tx

    I designed the mic preamp of my FM transmitter to be very sensitive, so it picks up all sounds in a room. If you speak too loud or are to close to the mic then the transmitter and radio will be over-modulated and will sound very loud and bad. Radio stations are never too loud. Speak to the mic...
  6. audioguru2

    Audioguru FM Tx

    A couple of years ago, Energizer's datasheets for their batteries had more detail and higher currents than now. I got this graph then:
  7. audioguru2

    audioguru fm transmitter

    Radar won't work. RF cops are alerted by people complaining about radio or TV interference. The RF cops use their van with a directional antenna on top and their receivers to find the transmitter causing the interference. The interference will occur if your transmitter operates at the same...
  8. audioguru2

    vehicle speed controller NEED HELP!!

    A little radio transmitter won't transmit far enough. You will need to get a licence to operate your own radio station. Then you can use a tranmitter that is powerful enough to cover the entire length of the road. A high antenna will help. Instead of transmitting the speed limit over the entire...
  9. audioguru2

    audioguru fm transmitter

    The oscillator signal is small, it comes from the oscillator's emitter. When Q3 is a class-A amplifier then it is biased and ready to amplify it. When Q3 is a class-C amplifier then the input signal must have an amplitude of at least 0.7V before it amplifies it. I didn't try it but Q3 might be a...
  10. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    I think NAND gates or NOR gates will work. I didn't look at XOR. Here are waveforms with NAND gates. NOR would make similar waveforms except the inputs go low to produce a high output.
  11. audioguru2

    1

    Digikey has many brands of 1uF/50V radial electrolytic capacitors that will probably fit on your pcb. They don't have them in 16V, 25V nor 35V anymore. 50V capacitors will work fine in your circuit.
  12. audioguru2

    1

  13. audioguru2

    1

    The 1uF/16V capacitors are only used at a few volts so only their value is important. Capacitors with a higher voltage rating will work the same but might be bigger. 1uF/25V or 1uF/35V might be small enough to fit on ther pcb. You are using the pcb, aren't you? This circuit works at around...
  14. audioguru2

    smd ones

    Datasheets for transistors have their power ratings. The datasheets also have all the other spec's that are needed to use the transistor in a circuit.
  15. audioguru2

    Audioguru FM Tx

    With a brand new 9V alkaline battery, I guess my FM transmitter has an RF output of about 250mW. I didn't make a meter to measure it. The battery current is 53mA max. The battery voltage quickly drops to 7.2V and the output power also quickly drops. Then the battery voltage slowly drops lower...
  16. audioguru2

    Electronic Fuel injection enhancer

    Sorry I was wrong about laughing gas (NOS). Your information talks about old catalytic converters that are more than 25 years old or for diesel engines. Newer catalytic converters reduce NOx.
  17. audioguru2

    Electronic Fuel injection enhancer

    If the catalytic converter is still there, then it should clean up the increased NO. If the converter has been removed then the people in the cars following will cough from the stink and smile from the laughing gas. I wonder why car manufacturers don't run the engines leaner??
  18. audioguru2

    DC Panel meter read errors on charger

    Then they aren't completely separate. With a separate winding on the transformer to power the meters. Or their circuit is designed for reading only a positive voltage then the negative input is the same as its 0V supply.
  19. audioguru2

    22 W Audio Amplifier

    My computer speakers are 3" drivers, 4 ohms, and are driven by an ordinary amp, not a bridged one like the TDA1554. Their power supply is 12VDC/1A and they are nice and loud when they are right in front of me. They are each getting about 3.5W at clipping and have huge magnets for such tiny...
  20. audioguru2

    DC Panel meter read errors on charger

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