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  1. L

    2 5V power source for a circuit

    The voltage requirements for USB is that at worst case (longest cables, highest drain, poorest connections) there must be a minimum of 4V3 _at the device_.  If the device in question can stand to run on as little as 3V6, then a diode in series with the supply will cause problems.  A diode in...
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    Please help on odd reference voltages

    If you are in no particular hurry, then I have a few TL431s and daughterboards I could spare.  They need two 1206 SMD resistors each for biasing.  They stand on edge and act like a two pin zener then finished.  PM me if you're interested.
  3. L

    Power freq 50hz or 60hz issue

    It depends on the appliance type and sometimes on the appliance itself.  Some things, like small power tools, blenders,  and devices with a switching power supply (computers, televisions, VCRs) are not likely to complain about going from 50Hz to 60Hz, but some might. Things with AC motors like...
  4. L

    Transformer question

    If it is the same frequency, then yes.
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    AC solenoids

    For the same reason iron filings stick to either pole of a magnet just as well.  The core of an AC solenoid is not polarized. Fewer components make it cheaper to produce.  Sometimes more reliable too. I will assume you are speaking of a DC magnetic field or permanent magnet.  It will have a...
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    OPA2134 Vs NE5532

    I am not an audio enthusiast.  That much said, I think I have seen a lot of things that use 5532 because of availability.  The THD of this device will be negligible compared to any other item in the system, unless you are using $600 headphones.
  7. L

    Driving 740 LEDs with variable intensity

    I won't say should.  If you have experience with them you will already know the advantages.  If not, then this project alone would not justify the costs involved with starting microcontrollers. I can't recommend using two computer supplies in series.  Some require a load on the 5V section. ...
  8. L

    Problem: two caps in ACDC unit?!?

    Is the transformer center tapped?
  9. L

    free energy motor

    This is going far, so I will say this. If someone does find a way to get unlimited free energy, I hope they destroy it along with all the evidence.  If such a source became available it would be abused in short order _WITH ABSOLUTELY NO EXCEPTIONS_.  We would incinerate ourselves.
  10. L

    Driving 740 LEDs with variable intensity

    Are you using a microcontroller?
  11. L

    Question for Electrician about unsafe voltages

    If it was the electrician's fault, then absolutely blame him.  If he did make modifications (which perhaps should have worked), then he should have notified you &/| left an as-built.  AC or DC, 12V or 120V, it's his job to know what he's doing and when he's outside his realm of training. ...
  12. L

    Adjustable precision shunt regulators, TL431

    For R2 I arbitrarily chose 10k- an easy number to work with, low enough current so as not to load heavily but high enough to suppress drift, readily available in 1% tolerance.
  13. L

    Any free a samples for Potentiometer

    A lot of manufacturers will have a means of requesting samples on their website.  The issue with switches and potentiometers is that they don't change much, so there is nothing new to attract innovation. If you only need one or two and the distributors in your area are charging too much, one of...
  14. L

    Adjustable precision shunt regulators, TL431

    This si a cool little device!  A few years ago I had a job that included scrapping power supply modules, and I noticed a few reusable parts on them.  The TL431 was one such.  I have a film jar full of them (very short leads though). Then I became aware of a PCB promotional offer, so I included...
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    IC 555 instead of IC 50240

    You sure are taking on a lot RF.  I hope you don't get bogged down and frustrated.  That willl be a nice toy when it is finished. The tuning on the original is by an R-C oscillaotr, but only one so everything is in tune with itself. You asked about microcontrollers earlier.  Do you have...
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    Drawing power from a single live wire

    I think you meant to put this here, and not in my message box. I have no way of judging your competence from here, and this is a hazardous project.  As such I don't know how much help I will give you, and it does depend on the information available to me.  How many cables enter the junction box...
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    Drawing power from a single live wire

    How many cables come into the j-box?  If there are two or more, then you almost certainly have a neutral wire to work with.  If there is only one, then the switch is downstream of the light that it controlls, but you may still have a ground wire available. For inline wiring without a...
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    Free sample chips!

    Someone from Central Semiconductor called me a few days after my sample request.  Some quesitons were asked (reasonable ones), some answers were given (true ones).  Not all of the items I asked for were in stock.  The CLDs were changed to a different value.  One of the TRIAC PNs was altered...
  19. L

    12vdc heating element

    Someone in this area uses greasel tool  He has two independant tanks- one for vegetable oil and one for diesel.  The vege oil tank gets it's heat from engine coolant.  He starts on diesel and switches over after a few minutes
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    Suggesion for LCD (Graphical or Charecter)

    Have you considered using LED?  Bright by day and dim by night.  If you don't mind committing a microcontroller to the display, then it should work nicely. If you have already decided that it must be LCD, then one I can suggest for economic reasons is the screen from an older Nokia cellular...
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