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  1. KrisBlueNZ

    Car Parking Sensors Help Needed

    Sorry, here's how I should have done it. Here is a parts list with references to Digikey product pages. 1x (C1) 6n8 capacitor http://www.digikey.com/product-detai...421-ND/2651653 2x (C2,3) 68n capacitor http://www.digikey.com/product-detai...1-1-ND/3881211 1x (C4) 1 µF 16V electrolytic...
  2. KrisBlueNZ

    Car Parking Sensors Help Needed

    OK, I made a slight change to the circuit - I changed the speaker driver circuit from bridge-tied-load to single-ended. This reduces the maximum output power to the speaker but I think you will be fine with the changed design. The speaker I've specified has an SPL (sound pressure level) of over...
  3. KrisBlueNZ

    LED Flasher help.

    Don't worry, I haven't forgotten you! I'm working on a design and a long circuit description. I hope you want to learn - if you don't, no problem; others may find it useful. I'm trying to make the circuit simple, but I suspect you'll say it's too complicated. I'm going to post it anyway...
  4. KrisBlueNZ

    Arduino Shield Question

    You're more likely to get an answer if you ask this in an Arduino-specific forum. Several Electronics Point members use Arduino, but if you go to an Arduino forum, _everyone_ there is an Arduino user. I just Googled Arduino forum and found six different sites on the first page of results.
  5. KrisBlueNZ

    connection of a thermal sensor TC1047AVNBTR to the microcontroller MSP430F4618

    I don't really understand your questions. The drive capability of the sensor's output is defined as a maximum allowable source and sink current of at least 100 µA. I suggest you connect a capacitor between the sensor's output and the 0V rail, i.e. across the sensor's output voltage. This will...
  6. KrisBlueNZ

    Roflcopter

    Generally, jokes are funny in some way. I think you meant trolling.
  7. KrisBlueNZ

    Help on circuit

    Hmm. I hadn't heard of oppositional defiance disorder but according to Wikipedia it's listed in the DSM, so I guess it's a "real thing" :-) If it helps, you could consider that I'm not _telling_ you to make the change because I _want_ it; I'm _suggesting_ the change because it would make the...
  8. KrisBlueNZ

    connection of a thermal sensor TC1047AVNBTR to the microcontroller MSP430F4618

    I don't understand your questions. The ADC does have input capacitance and resistance. It will also generate pulses of current at its input during the successive approximation process. It's common to connect external capacitance (e.g. 0.1~1.0 µF) from the ADC input to 0V to absorb these current...
  9. KrisBlueNZ

    New and probably mainly confused

    LOL :-) I totally agree. I'm an ailurophile - a cat lover. If Erwin Schrodinger was still around, I would be reporting him to the appropriate authorities! Here in New Zealand it's the SPCA (Society for the Prevention of Cruelty to Animals); in England I think it's the RSPCA (Royal Society for...
  10. KrisBlueNZ

    Help on circuit

    Hi Fish! 1. Yes, I suppose you're right. The fact that it's a flyback diode doesn't change the fact that it's a series Schottky diode in the VCC path to the AVR. Sorry for the confusion; it was all in my head. 2. Are you sure that a mark-to-space ratio of 254:1 (a duty cycle of 99.6%) is...
  11. KrisBlueNZ

    connection of a thermal sensor TC1047AVNBTR to the microcontroller MSP430F4618

    Well, I tried Googling TC1047A PSPICE model but didn't find anything. I found a Microchip document that says they have PSPICE models for their op-amps and comparators, but it doesn't mention models for their transducer devices, and the document does cover them, so I take that to mean that they...
  12. KrisBlueNZ

    Help on circuit

    Hi Fish! Regarding the VCC dip on the AVR causing resets, you could consider using a small diode (probably Schottky) in series with the VCC supply to the AVR and decoupling it at the AVR with say 100 µF at the AVR VCC pin (with a 0.1 µF MLCC in parallel of course). Thanks for posting the scope...
  13. KrisBlueNZ

    Roflcopter

    Five bands is normal nowadays for through-hole resistors - three digits, multiplier, and tolerance. They could have used an SMT resistor, but they don't look very interesting.
  14. KrisBlueNZ

    H-BRIDGE schematics

    Good advice Fish.
  15. KrisBlueNZ

    Stop circuit when battery drops below 3v?

    True. There's probably a comparator with built-in reference available in through-hole, but that MOSFET is only available in SMT. That, and the fact that the circuit is for a portable device and therefore needs to be small, is why I suggested an all-SMT design. :-) LOL Chris!
  16. KrisBlueNZ

    Protecting Driver Transistor from Transformer/Coil Back EMF

    Re improving the oscillator, I think your best option is the circuit described in http://www.electronics-tutorials.ws/waveforms/555_oscillator.html under the heading "Improved 555 oscillator duty cycle". This design adds a diode (e.g. 1N914) from pin 7 to pins 6/2 (anode to pin 7) and provides...
  17. KrisBlueNZ

    Protecting Driver Transistor from Transformer/Coil Back EMF

    OK, I'll write something up. Limiting the collector voltage to 100V is probably not going to work - that voltage is too low. When the IGBT turns OFF, the flyback voltage at the collector needs to go high enough to produce the required voltage at the top end of the ignition coil. Assuming the...
  18. KrisBlueNZ

    H-BRIDGE schematics

    I can see why you call yourself "reviser" ;-) Edit: The "DELETED" and duplicated posts that I was referring to are now gone... And I can't delete this post! Now I'm the one that looks like the "reviser"!
  19. KrisBlueNZ

    assembly program for 8051

    Wrong. 1. It's better to use the 8051's bit manipulation instructions on the ports instead of reading and writing whole 8-bit bytes from/to them. The syntax for referencing bits in SFRs is different for different assemblers. What assembler are you using? 2. You haven't shown a schematic, but...
  20. KrisBlueNZ

    Stop circuit when battery drops below 3v?

    I guess so. I don't consider the Chu Moy headphone amp to be complicated either. OK, I won't bother doing an SMT layout then. Edit: What I meant was that I wouldn't bother doing ANY layout.
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