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  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Recent content by KMoffett

  1. K

    Automatic chang parameter in pcb

    Contact the manufacturer!
  2. K

    Chinese VAT Refund on PCBA?

    Slightly another China issue. I last night's Biden-Trump debate Trump said China was paying the tariffs he imposed. Not exactly a quote, but Biden said it's the US importers and customers that pay. Trump said "NO!". I just received an order from DIGIKEY. There, in the itemized invoice was a...
  3. K

    Auto Load Sensing Switch A/C

    Congratulations for fighting through to a success. Ken
  4. K

    Auto Load Sensing Switch A/C

    Yeah! :) I missed that error in wiring that pot too.
  5. K

    Auto Load Sensing Switch A/C

    Don't make another perf board. It gets very confusing. So a little trouble shooting with your DMM on the 20VDC scale. I will use the schematic in Post #75, You choose the perf board we will refer to. 1. Attach the (+) probe to the +12v rail. Leave it there for now. You are going to measure with...
  6. K

    Auto Load Sensing Switch A/C

    The 10KΩ resistor on the 50K pot and the 47KΩ on the 200K pot are to keep the resistance from going to zero. Do the bread boards all work?
  7. K

    Auto Load Sensing Switch A/C

    You say the bread board wiring works. I noticed that there are no LEDs on that. I see three 10KΩ resistors on the bread board but only one on the perf board. So your perf board(s) are not the same as you bread board.
  8. K

    Auto Load Sensing Switch A/C

    What are you seeing with the problem boards? Is there any functionality? The schematic and your sketch appear to agree. Except: 1. The OFF delay pot in the schematic is 200KΩ. In your sketch you have 200Ω. Miss labeled? 2. The OFF delay resistor connected to the pot is 47K in the schematic. In...
  9. K

    Short-Circuit Protection for 3-6 Volts AA Batteries

    Please post your circuit that the batteries are connected to.
  10. K

    Liftmaster CPS-EI Interface

    I thought this was about the module for "Edge Sensors" not optical beams.
  11. K

    Liftmaster CPS-EI Interface

    I've had a bunch of HVAC temperature controller modules go bad because they had filter capacitors next to heat generating components, like that regulator. Couldn't move them so installed new caps wrapped in shiny aluminum foil, and never had a return. Check that electrolytic.
  12. K

    Liftmaster CPS-EI Interface

    Symptoms? and a photo of interior (lighted and focused!)
  13. K

    Auto Load Sensing Switch A/C

    rjenkinsgb is right. Note where the common is attached in my circuit. Attached.
  14. K

    Auto Load Sensing Switch A/C

    According to this link: 2n3904 pin#1 is the emitter and #3 is the collector. Maybe you simulator is in error. Other than that and the added resistors and LEDs, it it looks like mine and should work. Ken
  15. K

    Relay - most basic coil relay to show operation

    R. William, You never relly stated the purpose of the relay. Is this for a class project?

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