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  1. audioguru2

    amplify the power (infrared)

    A 2.2k load on a 100k collector resistor is still a huge attenuator. My suggestion of using a high impedance non-inverting opamp allows the photo-transistor to have its full gain. I just noticed that R1 was 470 ohms which is much too low. It should be a much higher resistance for good...
  2. audioguru2

    to anyone new to robotics

    The shelf life of alkaline cells exceeds 5 years so they are fine to keep in a flashlight in a drawer for years. Ni-MH cells self-discharge in 2 months. Your flashlight with them wouldn't work.
  3. audioguru2

    to anyone new to robotics

    Alkaline battery cells have a voltage of 1.5V, right? Ni-MH rechargable cells have a lower voltage of 1.2V, right? Look at the difference when they have a 250mA load. The Ni-MH rechargable cell's voltage is above 1.2V about 3 times longer than the Alkaline cell, and can be recharged 1000 times.
  4. audioguru2

    amplify the power (infrared)

    Hi Ryan, Due to a severe impedance mismatch, your IR receiver has an enormous loss. R1 is the high value of 470k so that the phototransistor has a high gain. But the value of R2 is so low at only 1k that the output of the phototransistor is nearly shorted. The opamp should be a type that works...
  5. audioguru2

    amplify the power (infrared)

    Hi Ryan, Your LM324 doesn't have its negative power supply pin 4 connected to a negative supply, no wonder it doesn't work. If pin 4 is connected to ground then the opamp would be an AM detector. Also, the LM324 has crossover distortion and a very lousy high frequency response, it drops above...
  6. audioguru2

    amplify the power (infrared)

    What is the DC modulation input levels? Please attach the schematic of the receiver.
  7. audioguru2

    9v + (2xAAA) = ????

    If the switch has more than one contact then it is two switches in one like I said to use.
  8. audioguru2

    amplify the power (infrared)

    Hi Ryan, It looks like a 1MHz oscillator that is amplitude-modulated by the input signal. A photo-diode or especially a photo-transistor doesn't work at such a high frequency as 1MHz, so I recommend using a lower frequency such as the 38kHz to 40kHz used by remote-controls. Please attach the...
  9. audioguru2

    9v + (2xAAA) = ????

    Since their supply voltages are very different, just use a two-pole switch that is two switches but with one toggle.
  10. audioguru2

    Help: White - Pink Noise Generator

    Of course you can fix the problem: just replace any ceramic "microphonic" coupling capacitor with a metallized-plastic-film capacitor. Connect a full-range speaker to the circuit and tap on the coupling capacitors. Then you will hear which capacitor is microphonic.
  11. audioguru2

    Use a speaker as a microphone while useing it as a speaker

    You can't multiplex a speaker as a microphone. A speaker needs the extremely low output impedance of the output of an amplifier across it to stop it from moving after it was playing sound. Because a speaker has resonance, it sounds bad as a microphone.
  12. audioguru2

    Happy birthday Logan

    Yeah Logan, Happy Birthday and congratulations for your graduation. ;D ;D
  13. audioguru2

    Strange behaviour of 78xx reg.

    With a 30 degrees C ambient temperature, at a power dissipation of only 1.75W, a 78xx regulator in a TO-220 case without a heatsink is at it max allowable operating temp of 125 degrees C for the chip and 118 degrees C for its case. With a power dissipation of 2.22W then the chip reaches 150...
  14. audioguru2

    500W 12v to 220v Inverter

    Hi Doron, I don't know if your resistors are rated at 0.3W or at 3W, but they certainly will blow. Their value is 2.4 times too high, so they will get 2.4 times hotter than the required 0.1 ohm/10W resistor, but since your load is "only" 400W then each of your little resistors will dissipate 24W...
  15. audioguru2

    Plants wattering watcher

    Make two compost piles. One with a circuit and the other without. Then see the results and the extent of the current.
  16. audioguru2

    500W 12v to 220v Inverter

    The 500W inverter will draw 600W from a 12V battery. The transistors draw a total current of 50A so each of your emitter resistors will have 50/4= 12.5A through it and will dissipate (12.5 squared) x 0.24 ohms= 37.5W each for half the time. So the inverter's output will be reduced by 37.5W x 4=...
  17. audioguru2

    need help on project amplifier design

    Most speakers are 8 ohms. Choose how much power that you want. Then design a simple class-B then a simple class-C audio amps that will have high distortion. Many circuits on the web are low-power audio amps that use three transistors.
  18. audioguru2

    LED Fade on, Stay on, then Fade off

    Hi Techno, Welcome to our forum. ;D Nobody replied to your request for a circuit because maybe it is not practical: 1) White or blue ultra-bright LEDs need about 3.5V plus some voltage for a current-limiting device plus more voltage for a voltage-ramping (fader) transistor. Two 3V lithium cells...
  19. audioguru2

    Hey all. New member ere. A little help please??

    Some questions are posted in more than a single topic and in more than a single web-forum. The answers are very confusing to follow.
  20. audioguru2

    Lowpass filter for subwoofer

    The supply bypass caps are ceramic. The four tuning caps are 5% metallized plastic film. They are rectangular in the photo.
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