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  1. KrisBlueNZ

    Stop circuit when battery drops below 3v?

    That circuit is not complicated. Nine components is not a big deal. No, I don't think you can do it any other way. Removing the hysteresis would only save one resistor. Two of the components I used in the design are SMT (surface-mount technology) so it makes sense to use SMT for all the...
  2. KrisBlueNZ

    Help on circuit

    Fish, a few comments on the schematic in your post #43. I'm not sure how your boost circuit will regulate. I would expect that as you vary the duty cycle to the MOSFET, the output voltage at the AVR's VCC pin will vary over a wide range. You would have to add a zener to protect the AVR, and...
  3. KrisBlueNZ

    3DS XL turns on, screens remain off

    It might be possible to troubleshoot it, especially with a fault that could be something minor, but without a schematic diagram, it would not be easy. I think the approach you're taking is a good one.
  4. KrisBlueNZ

    assembly program for 8051

    You're wrong. Do you understand my explanation in post #5? If not, you need to learn more about digital electronics and binary logic. Then you should be able to understand the 8051's I/O port architecture. Here's another reasonably good 8051 tutorial I found...
  5. KrisBlueNZ

    3DS XL turns on, screens remain off

    You said it "turns on" but there's no sound and no display. How do you know it has turned on? Have you looked for forums specifically about this device or other video game units? That's probably the best place to find people who have tinkered with them and have some familiarity with them. You...
  6. KrisBlueNZ

    assembly program for 8051

    The standard 8051's digital I/O ports are "quasi-bidirectional" and are not explicitly configured for either input or output. There is no data direction register or tri-state control register as there is on most other microcontrollers. Each port has an output register and an input register...
  7. KrisBlueNZ

    Is anyone using DesignSpark PCB?

    I just tried out DesignSpark PCB 5 for the last hour or so. I found it very difficult to use. Slow and clunky to do the most basic things like rotating a component. I couldn't even find basic outlines for the PCB such as SOIC-8. The few components I did try to place on the PCB generated an error...
  8. KrisBlueNZ

    Altronix power supply

    OK. It looks like the 8-pin IC is a Microchip 12F675 microcontroller; it's probably not directly involved in controlling the power supply. The device attached to the heatsink is the switching device and it includes the control circuitry. It's a Power Integrations TOP227YN and it's a member of...
  9. KrisBlueNZ

    Altronix power supply

    Thanks for that. The only device I can see there that could be the controller is the one you've marked "i/pe39qw / 1147". I can't find any power supply controller called PE39 or IPE39. (The "1147" is probably the date code - 47th week of 2011.) I need more information. Can you post a closeup of...
  10. KrisBlueNZ

    Protecting Driver Transistor from Transformer/Coil Back EMF

    Hi Tom. A few comments on your schematic in post #6. 1. You NEED to put a resistor in series with the pushbutton. The way you have it drawn, when the pushbutton closes you will be applying 6V across the base-emitter junction of the "51A" transistor. This will cause excessive current to flow in...
  11. KrisBlueNZ

    H-BRIDGE schematics

    Your design looks pretty good to me. You should have decoupling capacitors on the inputs and outputs of the 78xx regulators. I'm sure you knew that! I have a few other suggestions but I have little experience with H-bridges so please take my comments with a grain of salt. The IR2110 looks...
  12. KrisBlueNZ

    Altronix power supply

    OK, thanks for the pics. The markings on the semiconductors aren't visible; could you either post a list, or annotate the pictures. Edit: I'm doing other stuff for a few hours now.
  13. KrisBlueNZ

    Rewiring 7-band EQ

    Just minimise the total amount of copper on the stripboard that is connected to it. That's all.
  14. KrisBlueNZ

    Altronix power supply

    OK, that's good. Now can you do the other things I asked for in post #7.
  15. KrisBlueNZ

    Altronix power supply

    OK, can you measure the voltages across each of the big electrolytics with mains on, and see what happens to the voltage when you remove the mains. Both capacitors should discharge. Make a note of how long they take to discharge to less than 10V each. You might want to try to get a schematic...
  16. KrisBlueNZ

    Altronix power supply

    OK, it's a switching supply. These can be difficult to fix, and they're also more dangerous to work on. I'm not sure whether you want to proceed with this. Assuming you do... According to the Altronix web site, the AL400ULXB has been superseded by the AL400ULXB2, which looks significantly...
  17. KrisBlueNZ

    LED Flasher help.

    Great! You have now given me a clear specification. I have one more question. The three flasher circuits are independent and their frequencies will not be exactly the same, because of component tolerances. When they are enabled in pairs, the flashing of the different colours will not stay in...
  18. KrisBlueNZ

    Rewiring 7-band EQ

    That looks OK. It's quite spread out though. You can save a lot of space by mounting the resistors upright instead of lying down. You might want to try a program called diylc (DIY layout creator). It's a free Java program so it's multi-platform, and it allows you to create a nice-looking layout...
  19. KrisBlueNZ

    Altronix power supply

    Hello Brian and welcome to the Electronics Point forums :-) Current flows though a circuit; voltage is measured between two points - for example, across the fuse, or between one side of the fuse and the neutral wire. Take the fuse out and measure it with a multimeter set to resistance or...
  20. KrisBlueNZ

    Stop circuit when battery drops below 3v?

    Thanks Steve. I'm glad the MOSFET's power dissipation won't be exceeded during switching, because it would be hard to calculate the switching time. The comparator output is only rated for 30 mA (typical short circuit current is +/- 50 mA), hence the 100 ohm series resistor (probably...
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