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  1. KrisBlueNZ

    How does this circuit work?

    My gut feeling is that it's not likely to be a single faulty output pin. I think it's more likely that the micro is detecting a problem before it even tries to enable the motor, or there is some other problem that's preventing it from generating a PWM signal on that pin. This is just based on...
  2. KrisBlueNZ

    Need help with strobe circuit

    Here's my suggestion. The 555 produces a rectangular output wave with a period of about one second. Each time the output changes state, C3 charges up or discharges, and there is a burst of voltage across R3 as it does so. The four diodes form a bridge rectifier that converts that voltage...
  3. KrisBlueNZ

    Need Help with needed circuit

    Yes, you can use a smaller relay. If your actuator draws 0.3A I would use a relay rated for at least 2A though. You should also change the values of the capacitors and the resistors, according to the coil current consumption. The relay I originally suggested draws 50 mA on each coil, and I...
  4. KrisBlueNZ

    Need Help with needed circuit

    Here's an idea. It uses a latching relay to remember the polarity and to provide the voltage inversion. Each time you press the button, it flips to the opposite polarity. The relay is rated for 8A and its detail page is http://www.digikey.com/product-detail/en/RT424F12/RT424F12-ND/1128677 The...
  5. KrisBlueNZ

    555 Timer Circuit and 4017 Decade Counter

    I agree with CocaCola. The claim that this 4017-based circuit gives a "very realistic effect" is rubbish IMO. I clearly remember the KITT display and there's no way a 4017 with a regular clock will produce an accurate simulation. I think there are some microcontroller-based designs available on...
  6. KrisBlueNZ

    Need Help with needed circuit

    Is this for an electric antenna extender? Does the linear actuator automatically stop at its limits? I'll try to draw something up. PS. How much current does the linear actuator draw?
  7. KrisBlueNZ

    Stripboard Layout Editor

    I've spent about 15 minutes on it, and it looks pretty good. Certainly a lot better than other stripboard layout editors I've tried. The next time I have a project to lay out on stripboard, I'll give you some detailed feedback.
  8. KrisBlueNZ

    How does this circuit work?

    I don't understand. You said the micro never enables the MOSFET, so I assume it would NEVER expect the tread to move, right?
  9. KrisBlueNZ

    How does this circuit work?

    Did you read my previous post fully? I suspect the micro is deliberately not enabling the motor because it has already detected a sensor problem, because the sensor is faulty, or because it is detecting a genuine problem. This is consistent with the results of your tests so far.
  10. KrisBlueNZ

    LED strobe circuit needs more current

    I understand. It's just that when we ask questions, we ask them for a reason, even if the reason may not be obvious to you. It's frustrating when these questions don't get answered, especially if we ask them several times in a row. Yes, and I must apologise back to you Jim. You had said that...
  11. KrisBlueNZ

    Questions about a simple variable power supply

    Aww thanks :-) I should have explained in my previous post: the reason why we're all concerned is that we don't know what you intend to use this power supply for. The output is potentially very dangerous. If you intend to use it for experimentation, where you will be connecting wires and...
  12. KrisBlueNZ

    Questions about a simple variable power supply

    It sucks current, which decreases the gate-source voltage and makes the MOSFET "turn OFF more". As the load current increases past the limit value, the transistor starts to conduct and starts to suck bias away from the MOSFET. The MOSFET conducts less, and the output voltage drops. Assuming the...
  13. KrisBlueNZ

    LED strobe circuit needs more current

    Yes, canny. It took me a special request just to get the power supply information out of you. Everyone on electronics forums likes to help, but you really can save us a lot of time and effort by giving us a thorough description of what you want to do, and all the factors that have been decided...
  14. KrisBlueNZ

    Potential divider problem

    24Volts, it's a matter of the polarities of the currents. Currents that feed INTO the node are positive; currents that feed OUT of the node are negative. In this case, i2 (45.5 mA) and i3 (13.6 mA) both feed OUT of the node. So my formula could be rewritten as: 59.1 + (-45.5) + (-13.6) = 0 mA as...
  15. KrisBlueNZ

    Motorcycle Flasher Issue

    I've had a quick look through this thread. I may have missed something, but it seems like you already have a 6V battery on your bike. So the only reason you're using a 6V-to-12V converter is because your flasher needs 12V. Right? You can easily run the 555-based flasher circuit at 6V. Then it's...
  16. KrisBlueNZ

    Could this circuit work?

    The circuit shows the diode as a 1N4001, which is just a standard silicon diode. It doesn't produce any kind of signal. You would need to use a photodiode if you want the circuit to do anything useful.
  17. KrisBlueNZ

    Motorcycle Flasher Issue

    Have you tried just putting a diode in the supply line to the 555? Where Chris suggested inserting a 10 ohm resistor (between the light bulb and the 555 pins 4 and 8), add a diode in series with that resistor, and put at least 100 uF smoothing across the 555. Another straw to grasp at!
  18. KrisBlueNZ

    Questions about a simple variable power supply

    duke37 has answered your questions pretty well. I have a few things to add. 1. The reason for limiting the gate-source voltage of the MOSFET is that the MOSFET gate has a very high impedance and can easily be driven to any voltage, but if the gate-source voltage exceeds about 20V (positive or...
  19. KrisBlueNZ

    Potential divider problem

    That's how Thevenin equivalents work. Here's a simple example that should make it clear: . . . . . . . . . . . 2k . . . . . . . . . . 2k +10V -----------\/\/\/\/\/--------------\/\/\/\/\/------------ 0V . . . . . . . . . . . . . . . . . . | . . . . . . . . . . . . . . . . . . ------ point "X"...
  20. KrisBlueNZ

    LED strobe circuit needs more current

    I agree. But he seems to have a fixation on using these PCBs which are based on that design. I wasn't inclined to continue with that design, but I was able to make several improvements without hugely changing the circuit. You know, more than half of the schematics I see on the net have at least...
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