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  1. KrisBlueNZ

    NPN circuit not behaving...

    Thanks Chris and Steve for the feedback. I'll create a new symbol that shows both transistors but doesn't take up a huge amount of space.
  2. KrisBlueNZ

    Low voltage sine wave output

    Yes, C6 and C7 are right. You take the other electrode from the 0V rail of your circuit, i.e. battery negative or pin 4. The output voltage appears across R8. BTW I would use a higher value for R8 - something like 10k. That just reduces the load on the op-amp and decreases the power...
  3. KrisBlueNZ

    Help with hooking up open collector outputs

    Hi Mike. That's a pretty good description but I'll repeat it to make sure I understand you. So you have four buttons which are connected to a remote control circuit using five connections. One connection is the common for all buttons, and it measures +12V relative to the remote control...
  4. KrisBlueNZ

    Possible dumb question

    What is the make and model of the "buzzer"?
  5. KrisBlueNZ

    Splitting voltage across BJTs to avoid breakdown

    As Steve and John have already said, your transistors should be switching fairly low voltages. MOSFETs have a maximum allowable gate-to-source voltage, Vgs(max), which is typically in the range 10~30V with either polarity. If you exceed that voltage, the gate insulation will be damaged and the...
  6. KrisBlueNZ

    Low voltage sine wave output

    That looks right to me. It's pretty hard to follow, but if you have to work with an 8-pin block instead of two op-amp symbols, it's impossible to make it clear like Bob's original drawing. I'd suggest adding a decoupling capacitor across pins 8 and 4 of the IC. In this case, a 0.1 uF ceramic...
  7. KrisBlueNZ

    noise in SPI line?

    1. Check your ground connection between the board and the breadboard. Perhaps the USB logic analyser is making the ground connection when you plug it in! 2. Also, minimise the length of the ground wire to reduce its inductance to minimise ground bounce at the ADC. 3. If edges are too steep, try...
  8. KrisBlueNZ

    Help with amp

    Also, Q3 should be specified as a TIP41C. The TIP41 (no suffix) is only rated for 40V Vce!
  9. KrisBlueNZ

    NPN circuit not behaving...

    On that subject, what do you guys think about my Darlington transistor symbol? It's a standard transistor with two arrows on the emitter - see Q1 and Q2 in the diagram on https://www.electronicspoint.com/help-amp-t262454.html#post1565548. I haven't seen it before; I just use it to save space...
  10. KrisBlueNZ

    NPN circuit not behaving...

    Yes, I would have drawn it as a box containing two diodes, internally commoned at the cathode. That's how it's shown in the data sheet as well. The symbol you are currently using seems clear enough in meaning - at least, when shown in the context of the whole diagram. In fact I didn't...
  11. KrisBlueNZ

    Changing the speed of a walkman motor with motion

    Both of those circuits are fairly low-resistance, so you should go for the LDR that has the lowest resistance values, otherwise the LDR will have no detectable effect unless it's very brightly illuminated. I suspect this will be a problem no matter which LDR you get, but it's still worth a try...
  12. KrisBlueNZ

    High Voltage Regulator Circuit Help

    In that case, why are you repeating your error? Because writing mega-amps when you mean milliamps is not a cool way to advertise your uniqueness; it's a way to be wrong and embarrass yourself.
  13. KrisBlueNZ

    Pulsated LD

    Amen Chris. Darwin put it nicely: "Ignorance more frequently begets confidence than does knowledge." I am amazed by the attitude of some folks. They see the latest cool device on a popular science show, and immediately assume, because they were able to follow the simple description of how it...
  14. KrisBlueNZ

    Op Amps: Unwanted Oscillations

    Well, I guess, if you ever try it again, and have the same problems, post a schematic, a photo of your breadboard layout, and a photo of the oscillation waveform.
  15. KrisBlueNZ

    Changing the speed of a walkman motor with motion

    Here's the info for the other walkman - the WM-FX443.
  16. KrisBlueNZ

    Changing the speed of a walkman motor with motion

    I also downloaded the data sheet for the Mitsumi MM1038 IC that controls the motor speed. You should be able to get it as http://datasheet.elcodis.com/pdf2/109/71/1097134/mm1038.pdf. Here's the important part:
  17. KrisBlueNZ

    Changing the speed of a walkman motor with motion

    I grabbed the service manual for the WM-FX423 from elektrotanya.com. Here is the relevant part of the circuit. That site also has the WM-FX443 but the site has a daily download limit. I'll get it tomorrow and upload the schematic in a separate post.
  18. KrisBlueNZ

    Question using EEPROM

    It's impossible to answer that question because you've provided NO information. If you describe your whole project thoroughly, we may be able to help. To start with, what microcontroller are you using? Have you looked at the data sheet for the microcontroller to find out how to access the...
  19. KrisBlueNZ

    Need help with 555 timer circuit

    Yes, I clicked the links and read your post. My feeling is that that type of connector is not suitable for connection to very thin individual wires; they could break while you are mating and unmating the connectors. If you want to use that type of connector, I would use a 2-pin connector and...
  20. KrisBlueNZ

    Need help with 555 timer circuit

    I'm not exactly sure what you want to do, but I wouldn't be connecting 30 AWG magnet wire to that type of connector - my gut feeling is that every time anything moves, the wire will bend, close to the solder joint, and eventually it will break. Personally, I would run the wires from the LEDs to...
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