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  1. BobK

    PIC16F870 frequency counter

    So you have these pulses coming in. How might you determine their frequency? You should be able to think of two ways to do this. Bob
  2. BobK

    IDENTIFY Transistor from its Hfe Value

    The main characteristics you are interested in for picking a transistor in a switching application are: Vceo - the breakdown voltage between emitter and collector Ic - the max collector current Hfe - the common emitter current gain Vcesat - the saturation voltage between emitter and collector...
  3. BobK

    How to detect a plug is connected to socket

    I thought you were going to use the contactor to provide power to the plug. Presumably, then, when the contactor is off, there is no power to the plug. However, I would think that checking for continuity would be dangerous since if the contactor is turned on when you have an additional circuit...
  4. BobK

    New to Electronics: Is there any low voltage LED strip that can be powered with battery for Arduino

    Yes you can. It does PWM with 8 bits for each LED. If you make the 8 byte 11111111 you are using 20mA. If you make it 0111111 then you are using about 10mA average current. If you use 0001000 you are using about 1.25mA average current.
  5. BobK

    picking components for a stir plate

    That sounds more like it. I believe computer cooling fans will operate correctly on PWM since the ones in computers are always controlled that way. I think the disclaimer was for brushless motors that need a separate controller. Bob
  6. BobK

    Would like to convert a DPDT switch...help!

    How about soldering components on a perfboard? Bob
  7. BobK

    How to detect a plug is connected to socket

    Are you talking about a mains power socket and plug? Bob
  8. BobK

    Would like to convert a DPDT switch...help!

    Okay, easiest way would be with a microcontroller. Do you have any experience? Bob
  9. BobK

    picking components for a stir plate

    You could always replace the pot with a panel mounted one. Bob
  10. BobK

    Microcontroller controlled by pushbutton for LED flashlight

    Okay, great. As usual Kris had a good idea, and it should be workable. Bob
  11. BobK

    picking components for a stir plate

    I would suggest that you get a bunch of 10Ω 1W resistors and see how many you can put in series and still have the max speed you want, then add a 100Ω pot. Or, you can get a PWM motor controller off EBay for just a few bucks that will be far superior. Edit: something like this...
  12. BobK

    Microcontroller controlled by pushbutton for LED flashlight

    Thanks. So I guess the capacitor provides power to the uC when the light is on, and it is (hopefully) in sleep mode during this time. Bob
  13. BobK

    Would like to convert a DPDT switch...help!

    How is your electronic knowledge and skills? Bob
  14. BobK

    Would like to convert a DPDT switch...help!

    You could also possibly detect the limits electronically by detecting an increase in motor current when it hits the end of travel, assuming the mechanical setup will not be damaged by doing that. Bob
  15. BobK

    Microcontroller controlled by pushbutton for LED flashlight

    Trying to follow this thread to see if I can help. Can someone post an up to date schematic? I really have no idea what we are talking about now. Bob
  16. BobK

    New to Electronics: Is there any low voltage LED strip that can be powered with battery for Arduino

    WS2812 type strips operate on 5V, and have individually programmable LEDs. They can take a lot of current though. 1m at 60LEDs with all 3 colors fully bright takes 3.6A. For indoor use you can probably run them at 10 to 20% of that current through, and you will not have all of them on all of...
  17. BobK

    2ch remote with l298n and nema 17 connection

    Then the remote has to start a circuit that will put out the exact number of pulses for the needed number of steps with the proper timing, and set the desired direction. A microcontroller is simplest hardware you could do this with. You cannot simply hook up the parts you have and make this...
  18. BobK

    Microcontroller Help!!

    To measure low frequencies you want to start a timer at one pulse, the capture it at the next pulse. Or, let it run freely, and capture at each pulse and subtract the previous from the current value, adjusting for overflow if necessary. Bob
  19. BobK

    Level shifter

    Looks to me like he did a screen capture. Bob
  20. BobK

    Building Preamp from kit but a resistor keeps burning up

    It looks to me like there are several possible solder bridges there underneath the capacitor in your picture. Bob
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