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  1. Audioguru

    9014 Direct Replacement???

    The collector of the NPN turns on the base of the PNP. The PNP is a power transistor on a heatsink so it can have a high output current.
  2. Audioguru

    A Stretch

    When the battery voltage becomes too low for the the old 741 opamp then it stops working. The old 741 opamp was designed 52 years ago to use only a 30V power supply. Maybe your opamp stops working when the battery voltage drops below 8V or 7V. Try the circuit when it is powered from 12V.
  3. Audioguru

    9014 Direct Replacement???

    As a follower, the Sziklai pair has half the voltage loss of a darlington but it has the same current gain.
  4. Audioguru

    9014 Direct Replacement???

    Here is the tiny schematic posted and a larger one from Google. The transistor cannot be a Mosfet unless you use a much higher supply voltage and change some resistor values. Use a power Sziklai follower.
  5. Audioguru

    Chasing down excessive power consumption

    Each new streetlight has a modem antenna on top. I think the uncontrollable modems got cooked by heat from the LEDs or heat from the sun.
  6. Audioguru

    Chasing down excessive power consumption

    Your home lighting is designed to waste as much electricity as is possible. My home has 4 outside lights and the one for the side door is never used. The ones for the front and back are rarely used. My street has street lights (they are new LED ones and they are on all day and all night because...
  7. Audioguru

    Op Amp assortment

    Many guitar circuits use antique germanium transistors and vacuum tubes.
  8. Audioguru

    Op Amp assortment

    Most modern audio opamps have extremely low distortion and noise. But you WANT lots of distortion and noise! I have used thousands of TL071 (TL072 dual and TL074 quad) which are the audio version of the general purpose TL081 (TL082 and TL084). Today I use OPA134 (OPA2134 dual and OPA4134 quad)...
  9. Audioguru

    Op Amp assortment

    I bought my car from a car dealer, not from Amazon. I buy my groceries from a name Brand grocery store, not from Amazon. I buy electronic parts from Digikey or Newark (Farnell in Europe), not from Amazon.
  10. Audioguru

    Op Amp assortment

    The 741 opamp is 52 years old and its performance is horrible compared to modern opamps. Its datasheet shows only a 30V supply so many will not work when powered from a 9V battery.
  11. Audioguru

    Op Amp assortment

    The Amazon opamp assortment includes TDA7052A that is obsolete and has not been made for many years (fakes?).
  12. Audioguru

    9014 Direct Replacement???

    The dual opamp creates a triangle waveform that slowly brightens the LEDs then it slowly dims the LEDs. The transistor is an emitter-follower that is linear (not a switch) so it gets hot.
  13. Audioguru

    9014 Direct Replacement???

    The transistor here is used as an emitter-follower. If an N-channel Mosfet is used then its gate must have a fairly high voltage for it to be a source-follower.
  14. Audioguru

    9014 Direct Replacement???

    Your schematic is too small to see its details, but it looks like the dual opamp is a triangle wave generator driving the transistor as a linear emitter-follower. Then of course the little transistor gets hot and so will any little transistor. Add a power transistor to drive your bunch of...
  15. Audioguru

    A Stretch

    If your guitar has a volume control on it then it must be turned up to produce a high signal level. Then the gain control on the new circuit will control how much distortion is produced by the diodes.
  16. Audioguru

    A Stretch

    No. Pin1 is the opamp output and it should measure half the supply voltage. Pin4 is circuit ground and the minus terminal of the battery. Pin8 is the positive supply voltage. Pin2 is the inverting input. Pin3 is the non-inverting input. With pin6 shorted to pin7 then pin5 should be connected to...
  17. Audioguru

    Op Amp assortment

    Maybe the opamps you bought from Amazon the clothing and shoes online store are fake? Amazon and their sellers know nothing about electronic parts. The JRC4558 opamp was made by New Japan Radio Corp and is a old copy of a very old American MC4558. The American ones with pins are obsolete but...
  18. Audioguru

    A Stretch

    The gain control pot does not "go through the diodes and C31". They are all in parallel, not in series. C31 is only 100pF and the circuit should work with or without it.
  19. Audioguru

    A Stretch

    The circuit you have (without the horrible passive tone control) will work fine if it is built properly. If the opamp output measures half the supply voltage then the opamp is probably fine. Another circuit was shown to be exactly the same. When the gain control is adjusted to be zero ohms then...
  20. Audioguru

    A Stretch

    The old 4558 opamp has an open-loop DC gain of At least 20,000 times. Its inputs do not work properly (common mode input voltage range) if they are within 3V from a supply voltage. The input offset voltage is typically 2mV then the output might try to be at least +40V if the inputs are connected...
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