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  1. audioguru2

    How to find best Obsolete components

    If you find any obsolete components that still work then kiss them goodbye and bury them. Then use modern components instead.
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Army Vet. Did you build the original circuit or the modified circuit? Which power transformer and opamps did you use? The dim power LED indicates that the transformer voltage is too low maybe because it is overloaded with something shorted or because the rectifier diodes are connected wrong...
  3. audioguru2

    n-chanel eMOSFET data?

    An audio amplifier with a supply voltage as high as 200V will produce about 500W into an 8 ohm speaker and produce almost 12A peak, not a few milli-amps. Oh, is your amplifier going to use an old output transformer that has not been used for 50 years? Then its output power might be 1.8W into 8...
  4. audioguru2

    RPi Speaker

    It sounds awful like a squeaker, not like a speaker because the speaker is too small and it is not mounted in an enclosure. The LM386 amplifier produces only 0.11W (almost nothing) into 8 ohms when its supply is only 5V. 
  5. audioguru2

    TENS machines revisited

    Look in Wikipedia for Voltage Multiplier. It has an AC input to capacitors and diodes.
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    A dissertation is an essay. Why do you want an essay? Don't you understand what the parts in the circuit do? Do you know how transistors and opamps work?
  7. audioguru2

    c828 transistor

    More useful to do what function?? Many of us do not use those Japanese transistors. Instead we use BCxxx European transistors or 2Nxxxx American trasnsistors,
  8. audioguru2

    IC Issue

    An IC is an "Integrated Circuit" that is a tiny chip with many transistors, resistors, diodes and capacitors on it. Look in Google for a longer explanation. 
  9. audioguru2

    Issue with a 10 Watt Power LED Driver Supply

    An LED is driven from a current, not a voltage. We do not know if the high power SMD LED has a built-in current-limiting resistor. The LED sets its own voltage so the 17V - 19V will probably drop to 12V when the 12V/900mA LED is connected. 10W is a lot of heat for an LED. Do you have a suitable...
  10. audioguru2

    Issue with a 10 Watt Power LED Driver Supply

    A blue LED is about 3.2V but some high power LEDs have a few of the LED chips in series. If your blue LEDs survive the high current of 900mA then the eight you connected in series need about 25.6V which is much higher than the rated output voltage of the driver. Why eight LEDs? Try using a load...
  11. audioguru2

    Home Made Mobile Phone Charger

    The datasheet for a u7805 voltage regulator says its minimum input voltage is 7V. The 9VAC transformer has a peak voltage of 12.7V and the bridge rectifier reduces it to 10.9VDC so it will be fine when filtered by the 1000uF capacitor. It will not harm a phone because the phone has the charging...
  12. audioguru2

    12v 3a Transformerless Power Supply

    The capacitor will have AC across it, not DC so you cannot use a polarized electrolytic capacitor. I could not find a film capacitor rated at 47uF/400VAC anywhere. They were available 60 years ago, were very large and very expensive. But transformers are inexpensive and are available everywhere...
  13. audioguru2

    I'm struggling to understand the function of transistors

    The datasheet tells you that for this little transistor to saturate with a saturation voltage drop of maximum 0.3V when its collector current is 10mA then the base current must be at least 0.5mA so the ratio of collector current to base current is 10mA/0.5mA= 20. Most American little transistors...
  14. audioguru2

    Digital Ac voltmeter Using 7107

    300VAC has a peak of 424V that will arc across an ordinary 100k resistor and destroy any opamp. Use a high voltage 100k resistor, a voltage divider and a voltage clamp that limits the opamp input voltage.
  15. audioguru2

    What's the difference between MC14046B and CD4046?

    www.datasheetarchive.com has the datasheets from two manufactures of the very old CD4046A. Of course they also have the datasheets of the improved CD4046B, MC14046B and HEF4046B.
  16. audioguru2

    Digital Ac voltmeter Using 7107

    The ICL7107 is very old and has problems with accuracy when it warms up. The ICL7107S is an improved one. Its datasheet has a circuit that is recommended by the manufacturer.
  17. audioguru2

    What's the difference between MC14046B and CD4046?

    About 53 years ago the CD4046A was introduced but it had many problems. It was replaced a few years later by the improved CD4046B and MC4046B and HEF4046B. Your CD4046A must be one of the very old ones with problems. Look on the datasheets of an A and of a B to see the differences.
  18. audioguru2

    Relay Stuck

    I think the inductance of the load is producing a big spark in the relay contacts that welds them shut. Use a relay made to switch higher current. Its contacts will be larger and its spring will be stronger.
  19. audioguru2

    simple IR extender

    The added TSOP1738 on the left side of the schematic is mounted where your remote can shine its modulated 38kHz IR on it. It demodulates the signal and modulates the added 555 38kHz oscillator that drives an added transistor and added IR LEDs mounted where the TV IR detector can see them.  
  20. audioguru2

    simple IR extender

    The remote controls for my TVs work for 20 feet or more so yours should be fine at a distance of only a few feet. Maybe the battery in your remote is dead? I do not know what you call a "blaster". The TSOP1738 is not made anymore but there are similar ones available. Its output is the...
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