Search results

Search Forums New Posts
  1. BobK

    PS2 Controller Mod

    Dave, I think he is trying to reproduce the dead-bug wiring in the lower left corner of the picture you linked to. Bob
  2. BobK

    stupid questions

    That is a class AB audio amp, and I don't see how it could possibly work since the gain of the voltage amplifier is only a little over 1, and it claims to output 66V p-p from a 2V p-p input. I suggest that you read the Wiki article. People have died by using useless Rife machines instead of...
  3. BobK

    Are pull up / pull down mandatory ?

    Some microcontrollers can put out 20ma on a pin without a buffer. Which one are you using? Bob
  4. BobK

    stupid questions

    Time for the woo-woo label: http://en.wikipedia.org/wiki/Royal_Rife Bob
  5. BobK

    Sensing and measuring current?

    If you don't want a current sense resistor at ground, there are also high-side current sensing amps that can do this with the resistor on the high side. Look up "high-side current sensing amplifier" Bob
  6. BobK

    Are pull up / pull down mandatory ?

    Yes, when using tri-state you must have a pullup or pulldown. When using open collector you must have a pullup, or you will never see a high state. Bob
  7. BobK

    7912 as negative voltage regulator issue

    Look up the datasheet. It has a sample circuit. Bob
  8. BobK

    7912 as negative voltage regulator issue

    You have the ground and power reversed. For a negative regulator the ground has to be higher than the input. Edited: You also need the capacitors on the input and output. See the datasheet. Bob
  9. BobK

    How to make an audio device?

    A Raspberry Pi comes to mind. Bob
  10. BobK

    3W IR LED isn't very bright?

    And if this is how you respond to Steve's excellent advice, you should not bother to ask. You do not have a basic understanding of current and voltage in LEDs. Steve pointed you to an article that covers this, taking many pages of text. Do you expect Steve to type in all of that text again...
  11. BobK

    Are pull up / pull down mandatory ?

    As far as I can see, the two 10K resistors that you call pullup and pulldown are doing absolutely nothing (except wasting 330uA of current.) They are simply 10 K resistors from power to ground. If you wanted a pullup or pulldown it should be on the other side of the switch, i.e. connected...
  12. BobK

    Need help building a servo powered device.

    Go ahead, and see if you get any help when you cannot or will not answer their questions. Bob
  13. BobK

    3W IR LED isn't very bright?

    An NiMH cell is only rated at 1.2V. It is no wonder you are having trouble running a 1.5-1.7V LED off a single NiMH cell. I agree both with Steve for the ultimate solution, and with Duke for a way to try it out. However, be aware that the resistor must be a 5W one, and it is going to get...
  14. BobK

    Galvanic isolation DC/DC

    Most DC to DC converters are not isolated. You would need to find one that is, which will indeed use a transformer. Bob
  15. BobK

    12V DC to 5V DC iPhone Charging

    Yes, those would work, but this is cheaper, and does 2A. http://www.ebay.co.uk/itm/DC-DC-LM2596-Converter-Buck-Adjustable-Step-Down-Regulator-Power-Module-1-2-35V-/370624565910?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item564af21296 Bob
  16. BobK

    Making a temperature sensor

    Yes, I use a match. Bob
  17. BobK

    12V DC to 5V DC iPhone Charging

    If you use a 7805 you are wasting 7/12 = 58% of the energy. Use a DC-DC converter, which can be up to 90% efficient. You can find these cheap on Ebay. Also, be aware, that for Apple phones, you will have to put certain voltages on the D+ and D- lines of the USB connector in order to make it...
  18. BobK

    Making a temperature sensor

    I don't see any problem using heat-shrink on it. The soldering temp is going to higher than that needed for the heat-shrink. Bob
  19. BobK

    Will this circuit work?

    There are so many things wrong here, I don't know where to start, but I will anyway. Have you sourced the 4.7kF 200V capacitors? How much do the cost? How large are they? Bob
  20. BobK

    PWM voltage divider

    So it is an analog input? What is the range? If I understand you, you want to take the output of the load cell and reduce the voltage by a factor controlled by a uController. If this is correct, I still say a digital pot is what you want. Bob
Top