Search results

Search Forums New Posts
  1. Audioguru

    Building Portable AC power supply

    If your projector has an incandescent light bulb (a heater) then its current when it is turned on is maybe 250A! When its filament reaches 2 thousand degrees C then its current is much lower at maybe 25A. A 12V car battery can deliver 600A to a starter motor at 8V in winter for about 10 seconds.
  2. Audioguru

    Circuit help

    I copy and paste parts of datasheets and parts of other schematics into Microsoft Paint program to make my schematics. I Use LTspiceXVII program to do simulations after drawing a schematic in it, but its schematic has a grey background.
  3. Audioguru

    Piezo Preamp EQ

    Put a gain pot on the first opamp instead, because a gain pot on the tone control circuit ruins it.
  4. Audioguru

    741 op-amp

    Don't forget to compare their prices. The AD797 is the most expensive opamp I have ever seen. Maybe they make thousands and test them all then throw away (sell them on ebay) most of them that are not absolutely perfect.
  5. Audioguru

    YX86 1108

    A solar garden light is very inexpensive. If you buy a new one then seal around the solar panel so the electronics inside does not get wet. The bottom should be open a little so that humidity and condensation can get out. A modern solar garden light comes with a Ni-MH battery cell in a...
  6. Audioguru

    741 op-amp

    A 741 was introduced 49 years ago. It was not intended for hifi audio. It is noisy and with a gain of only 100 its output level drops above only 10kHz. Its poor slew rate causes distortion at high output levels above 10kHz. Why do you care about distortion at 20kHz? Are you an audiophool or a...
  7. Audioguru

    Frequency Generation Without An Oscillator Ckt:multisim Simulation

    50A in a little BC547? Why doesn't Multisim read the maximum allowed ratings on the datasheet? it is 100mA (0.1A).
  8. Audioguru

    Partialy Discharging Capacitor

    PWM varies the duration of each "flash" to vary the brightness. I understand that a flash duration of 30ms or more results in full brightness to our vision.
  9. Audioguru

    Circuit help

    The output of the nightlight should not be connected to ground! The gate of the Mosfet should not be connected to ground! Your two circuits have their grounds connected together (thank you). You changed the Mosfet to an N-channel (thank you). But you have the nightlight output and gate of the...
  10. Audioguru

    Replace Relay with TRIAC?

    A triac is usually used with AC but will work with DC (but then half of it is not used). An SCR is the half of a triac that can be used with DC. A Mosfet is a powerful transistor used with DC.
  11. Audioguru

    No AA battery terminal connectors in battery compartment

    I have some rechargeable battery powered things that work with Energizer Ni-MH batteries but do not work with Duracell Ni-MH batteries because the Duracell positive part is too short and does not reach the connector. They are both made in Japan.
  12. Audioguru

    Obtaining 1 Sec Clock Pulse From Power Line

    You must filter the power line because it is full of hash from light dimmers and high current things turning on and off. The counter will count all the hash. I bought clock radios that have a backup battery for $1.75 each at a surplus store. They sound awful but the clocks work well.
  13. Audioguru

    Led turn on when car interior lights turn on

    If you add additional lighting to the circuits then the electronic switches will be overloaded then soon burn out. You must detect the switch turning on the existing lights then turn on a Mosfet that turns on your LED strips.
  14. Audioguru

    Replace Relay with TRIAC?

    Triacs are used in AC light dimmers. Mosfets are used as DC switches in modern cars. Relays were used in old cars.
  15. Audioguru

    Charging batteries in boombox while using it

    A graph in the datasheet for the TDA7492 shows 50W per channel with a 25V supply and horrible-sounding clipping distortion. The minimum voltage on the graph is 15V but I figure 6W per channel into 8 ohm speakers with fairly low distortion when powered by this 12V battery. Music is never...
  16. Audioguru

    Circuit help

    1) You cannot turn on anything with only one wire. You need 2 wires. 2) For the P-channel Mosfet to completely turn on as the source-follower you show instead of as a switch, its gate voltage must be another 9V or 10V more negative than the negative terminal of the 9V battery. What is the 4V...
  17. Audioguru

    Partialy Discharging Capacitor

    Make a steady 350V for the trigger transformer circuit and make a variable main discharge voltage. I do not know if you can stepup the 12V to thousands of volts with one trigger transformer circuit.
  18. Audioguru

    Consultation

    1) Why do you have coupling capacitor C6? R5 should be connected directly to the gate of the Mosfet. 2) The 1N4007 power diode is made for 100Hz or 120Hz, not 15kHz. When C6 is removed then the diode is not needed.
  19. Audioguru

    Charging batteries in boombox while using it

    The charger for 10 cells will produce 14V to 15V. The maximum voltage for the amplifier is much higher at 25V so a voltage regulator is not needed. The battery and boom-box must be separated when charging the battery but the battery can be connected to the charger and the boom-box can be...
  20. Audioguru

    Noob? Electronic car horn for bicycle

    A noob must learn to look at the manufacturer's website to see if a product is still being made. A noob must look at the datasheet of an IC replacement and compare it to the original part's datasheet. The datasheet tells you everything about it. Philips (now called NXP) invented the TDA7052...
View older results
Top