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  1. Audioguru

    I want to design a single led to be powered by 4 garden-sized solar cells

    When you are charging a lithium battery at 4.2V with a large power supply, what is limiting the current if the battery has a problem? 4.2V x a high current= high heating and an explosion. Lithium, titanium and magnesium are flammable.
  2. Audioguru

    I want to design a single led to be powered by 4 garden-sized solar cells

    You are using the very old transistor as a switch. It must be saturated when used as a switch. Its datasheet and the datasheet for almost all datasheets say that to be a saturated switch then the base current must be 1/10th the collector current. Your base current is way too low then some 2N2907...
  3. Audioguru

    I want to design a single led to be powered by 4 garden-sized solar cells

    Your 1800mAh battery is probably a 18650 size which is a little larger than an AA. It is not new but if it is new then it will power three LEDs at 20mA each for 30 hours (2.5 12 hour nights). It needs a circuit to disconnect it when its voltage drops to about 3V and it needs a charger that is...
  4. Audioguru

    I want to design a single led to be powered by 4 garden-sized solar cells

    Didn't you do the simple math? Three LEDs at 20mA each use a total of 60mA. A huge dangerous (explosion and fire if not charged correctly) 18000mAh Lithium battery. 18000/60= 300 hours which is 25 nights of 12 hours each. Looking for huge 3.7V rechargeable batteries, I see that most AA size are...
  5. Audioguru

    Yusynth metaliser

    The almost 4 years of delay in this thread will not affect how it sounds. It will sound the same with a +/-12V supply.
  6. Audioguru

    Any Advantages of Tubes (Valves) Over Solid State & Microelectronics?

    Without my hearing aids, tube amplifiers sound the same as good solid state amplifiers because my old ears cannot hear the high frequencies of distortion produced by tubes. When I was young with good hearing I hated hearing the buzz and fuzz played by rock musicians using tube amplifiers. I...
  7. Audioguru

    Home Based Income as an Electronics Hobbyist

    Income? I am old so I am retired. Every day is a "Saturday" and I do almost whatever I want whenever I want. I made some savings and good investments during my electronics career and my government pays me and my wife pensions and other bonuses for seniors. Health care is paid by the government...
  8. Audioguru

    Complete novice considering a battery project

    The little battery produces 36VDC to 42VDC at 5.2A for one hour. Most TVs work from AC electricity that is 120VAC or 240VAC that is completely different than the battery.
  9. Audioguru

    RC engine sound simulator, how to install in 3yo kids rideable toy?

    You might make the sound level too loud. Formulas One race cars this year will have a sound system to make their little V6 hybrid engine sound like a huge V12.
  10. Audioguru

    RC engine sound simulator, how to install in 3yo kids rideable toy?

    Will your kid wear headphones to prevent your neighbors from hearing the noise?
  11. Audioguru

    Google nest mini speaker linkage

    A Google Nest Mini is modern so it probably uses a bridged amplifier that drives BOTH speaker wires without a "ground' connection. You might convert its output to an aux "RCA" signal if you add a capacitor in series with one speaker wire being the signal wire of a shielded audio cable with the...
  12. Audioguru

    Simple Wiring Question

    I have never wired high current. Lookup a list of wire guage spec's.
  13. Audioguru

    Simple Wiring Question

    Does the generator/alternator/voltage regulator supply enough current for the heating plus everything else? Do the heated clothes have an automatic temperature controller? Or you simply use an on-off switch?
  14. Audioguru

    MOSFET

    A little 2N7000 or 2N7002 will work if you find a sensitive one.
  15. Audioguru

    MOSFET

    IRFxxx Mosfets are fully turned on when the Vgs is 10V. IRLxxx Mosfets are "logic level" and are fully turned on when the Vgs is 5V.
  16. Audioguru

    MOSFET

    You do not need a Fet if you use the 3V input signal (with a series resistor to limit the current to about 5mA) to turn on the opto-input of the relay.
  17. Audioguru

    Bench power supply upgrade

    The first fake TL081 had offset pins connected to nothing. The second one blew up. I wonder if your third one has a third problem?
  18. Audioguru

    Bench power supply upgrade

    Didn't you replace all three fake opamps a while ago?
  19. Audioguru

    Bench power supply upgrade

    The output of opamp OP3 should always be about +10.2V but you said that it drops to 0V or -0.5V sometimes when the power is turned on. Its output low is about +1V so I do not see how it can be 0V or -0.5V. The setting of the voltage pot has nothing to do with the OP3 output voltage if the pot is...
  20. Audioguru

    Bench power supply upgrade

    The LED is driven by opamp OP2, not OP3. OP3 is the 10.2V reference that feeds the 10k voltage pot and the R23 56k resistor (I think its value was reduced so that the max current from the project is 2.5A) that feeds the 10k current pot so it is not possible for the slider of the 10k voltage pot...
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