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  1. BobK

    Is this circuit possible?

    Apparently you missed post #9. The input and output - are common. Which is true of the simplest boost converter topology, as Steve has been saying. Bob
  2. BobK

    Is this circuit possible?

    The post about recharging the battery was sarcasm. The post you quoted is fact. Colin says the output is not connected back to the input, I have shown that it clearly is. Bob
  3. BobK

    Is this circuit possible?

    Realy? Just follow the wires I have colored red from your schematic, Colin:
  4. BobK

    Is this circuit possible?

    But Steve, don't you see the advantage of Colin's circuit? The boosted voltage is fed back to the battery, recharging it. You never have to recharge the batteries! Bob
  5. BobK

    increasing voltage or current

    You can place LEDs with different forward voltages in series. As long as you set the current correctly, they will split the voltage as each requires. For example; 2 red LEDs Vf 2.5V 1 blue LED Vf 3.3V Total voltage of LEDs 9.1. So you need a resistor that drops (12 - 9.1) = 2.9V at 20mA...
  6. BobK

    5V boost converter efficiency?

    Are you measuring the current going into the boost converter and the current going through the solenoid and adding them? That would count most of the current twice. The input current is just the current coming from the battery. Hopefully this is closer to 200mA, the ideal amount. Edit...
  7. BobK

    Is it possible to use a stepper motor without a micro-processor ?

    That depends on what you mean by "drive". This minimalist driver will allow you to run the motor, but not to count steps for positioning for instance. Bob
  8. BobK

    small motors

    The first thing I would try is lubricating it. There should be a small hole(s) in the motor casing for this. Bob
  9. BobK

    increasing voltage or current

    Getting there, but you still have the LEDs wrong. You cannot parallel them with one resistor. The reason for going to 12V was to allow you to put several LEDs in series. You should be able to two string of 3 LEDs + a resistor in each string. Look at the LED resource again for how this is...
  10. BobK

    36v 7a class D bicycle trailer system... amps & capacitors?

    Okay, now that you have explained your need, I am willing to help. If I understand correctly, your amps are run by 36V supplied by 3 12V batteries in series. If this is so, put one capacitor, rated for 12V across each of the 3 batteries. But, that does not sound right to me. Where are you...
  11. BobK

    Is it possible to use a stepper motor without a micro-processor ?

    You can, but the circuit is way more complex without a microcontroller. Bob
  12. BobK

    increasing voltage or current

    That diode is in this circuit because it is running a motor. You would take out the diode and motor, and replace it with your string of LEDs and resistor, all in series. The LEDs should point in the opposite direction of the diode in your schematic. FYI the diode in the schematic you posted...
  13. BobK

    increasing voltage or current

    You are very confused about the meaning of Hfe. First of all, it is a pure number, not something measured in mA. The gain of a transistor is the ratio of the collector current to the base current under certain conditions. And it changes under other conditions. If you need 15mA of collector...
  14. BobK

    Electronic Inks!

    And you can draw capacitors if you use both sides of the paper! Bob
  15. BobK

    36v 7a class D bicycle trailer system... amps & capacitors?

    Yipes. Just did a Google image search. I had no idea that hauling around massive audio systems on a bicycle trailer was a "thing." Bob
  16. BobK

    How to design analog circuit

    It is for a test question. No practical use. Bob
  17. BobK

    IC 78XX

    Sorry, but internet skills are the best antidote for lack of knowledge. All you needed to do was enter 78XX in google and you would have found links to datasheets, which contain the circuit you were looking for. Bob
  18. BobK

    36v 7a class D bicycle trailer system... amps & capacitors?

    I have a strong moral objection to your project. The last thing I want, when riding on a pleasant bicycle trail is some idiot blasting his favorite music to detriment of everyone trying to enjoy a quiet trip away from such nonsense. Bob
  19. BobK

    IC 78XX

    If you have to ask that question, you need to improve your internet search skills. Bob
  20. BobK

    Reducing amps in a circuit without change in the voltage

    After a transformer, a circuit is what is called floating. It has no connection to any other circuit. You can connect a floating circuit to ground. We are speculating that the common of the DC output of your transformer is connected to ground in your adapter, which is perfectly OK to do. Bob
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