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  1. audioguru2

    PH meter

    Hi Steve, Look in Google for pH Meter Circuit. There are plenty.
  2. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Every inverter has an RMS power which is its average power to the load.
  3. audioguru2

    Fridge door alarm circuit

    It is a piezo beeper with a built-in oscillator. When the circuit applies a voltage to it then it beeps. The circuit makes a delay then makes the piezo beep 3 times per second. With only a 3V battery it will not be loud. With a 9V battery then it should be much louder. if the transistor is...
  4. audioguru2

    Speaker help please

    Your 6" rear speakers are too small for bass, so get a 10" sub in a pretty big enclosure (made for pickups) and use the Pioneer amplifier connected bridged for 160 real Watts. I hope the Sony car radio has an output for a subwoofer amplifier. There aren't any spec's for those tweeters. Go to a...
  5. audioguru2

    SMPS question...

    Go to an electronics surplus parts store. I bought some name-brand SMPS 5V/2A tiny and lightweight power supplies that were made by a computer router manufacturer for $2.50CAN each including taxes. Their voltage regulation is very good and their high frequency ripple is low. I have some similar...
  6. audioguru2

    Speaker help please

    I never bought separate car tweeters. Get dome tweeters with a 3/4 inch diameter dome (not just an old  cheap paper cone) with magnets. Piezo tweeters sound terrible and are just whistles. If the crossover network has an inductor and a capacitor or two inductors and a capacitor then a 3kHz...
  7. audioguru2

    problem in oscillator part

    Hi Max, The text in that very old project tells you exactly how to make it. It operates at a very high radio frequency where capacitance between two wires is too high and wires are inductors. It won't work if it is made on a breadboard. It must be made with very short wires on a pcb or on...
  8. audioguru2

    Speaker help please

    Hi Dot-com, I wondered, "55W per channel? How do dey do dat??" In Google it is 17Watts RMS per channel into 4 ohms. That might be with 10% distortion because it is turned up too loud, and with the battery overcharging at 14.4V. It is probably only 15Watts RMS per channel into 4 ohms at clipping...
  9. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Your 300W modified sine-wave inverter schematic is very fuzzy because you saved it as a JPG file type instead of saving it as a very clear GIF or PNG file type. I can hardly read it. The transformer should be 8.5V-0V-8.5V/230V for the output peak voltage to be root-2 of the voltage of a...
  10. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Where is the schematic of a 300W modified sine-wave inverter with a CD4047 and a CD4001? Does it use Mosfets?
  11. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Kachew, You described a power transformer for a 300W continuous power inverter.
  12. audioguru2

    A very Urgent Question

    Hi Walid, I think the very high supply current spikes from the 555 are interfering with the IR receiver. A 555 creates current spikes of 400mA on the power supply. The datasheet for an LM555 warns that the current spikes can affect other ICs on the same power supply and recommends using two...
  13. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Kachew, A simple inverter uses a fuse from the battery for its overload protection. If you need 300W of surge power then use a fuse for a little over 300W, a 200W transformer, a circuit that has a 300W output and heatsinking for 200W. Then a surge can draw 300W for one minute and the inverter...
  14. audioguru2

    Transformer question

    The power rating for a mains transformer depends on the size of the core and wire, the number of turns and a few other things. If the input is 120V and the output is 60V then a 20 ohm load would be 180W. It must be a pretty big transformer.
  15. audioguru2

    Transformer question

    At only 60Hz, the inductive reactance of the primary of an air-core transformer is like a piece of wire, a very low resistance.
  16. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The gate of a Mosfet is a capacitor. It needs current to charge and discharge quickly. For the low mains frequency the peak gate current of a few milliamps will be fine. The battery supplies 50A to the circuit only if the load on the inverter is 500W. The current from the battery and through the...
  17. audioguru2

    summing ampliier can i connect to GND intead Vcc-

    No. R supplies the input of the opamp with the +2.5V offset voltage. It is also a load for the signal source. Its value is selected for a low voltage drop caused by the input bias current of the opamp. The rail-to-rail opamp has a fairly high output resistance that reduces the output voltage...
  18. audioguru2

    summing ampliier can i connect to GND intead Vcc-

    The output of a rail-to-rail opamp will swing from 0V to +5V if the load is a high resistance and it operates from only a single 5V supply. Opamps have an "input offset voltage" that is up to about 10mV. You can add an offset adjustment pot to null the offset. Some opamps are "laser-trimmed"...
  19. audioguru2

    Transformer question

    Hi Indulis, Sure a transformer without a load has a high reactance in its primary winding. If you remove its core then it is just a very low resistance piece of wire. A resistive load on the secondary is reflected and stepped up or down to the primary in parallel with the very high reactance...
  20. audioguru2

    summing ampliier can i connect to GND intead Vcc-

    An opamp has an open-loop voltage gain of 200,000 or more so you don't want to apply a DC voltage to one input and the signal to the other input. The inverting input is for negative feedback to reduce the gain to a reasonable amount. You can add an offset voltage to the signal input like this:
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