Search results

Search Forums New Posts
  1. KrisBlueNZ

    DIY turntable build

    Solidus, listen to docb. He has direct experience and knowledge of DJ turntables. I had a look at the SL-1200 manual. It confirms what docb says, that it's direct drive. It uses a three-phase motor with three drive coils and a ring magnet. The relevant part of the schematic is the bottom right...
  2. KrisBlueNZ

    DIY turntable build

    Not so much that any hand action would STALL the motor, but it would change the speed of the platter, and it would take a while for the platter speed to stabilise afterwards. Re getting an actual turntable motor, it depends on the type of motor. What are you considering? A mains synchronous...
  3. KrisBlueNZ

    DIY turntable build

    docb yes you're right. You would need a firm drive because of all the hand action on the record. Even with the slipmat there will be a lot of rotational force on the platter. Definitely the best option would be the direct drive using electromagnets and a magnetic ring that I described first in...
  4. KrisBlueNZ

    DIY turntable build

    You mean a battery powered drill? Maybe, but they're designed for power, not smoothness, so they produce a lot of vibration, and you don't need anything as powerful as that. Something smaller that runs quieter and doesn't produce so much vibration would be better. Perhaps a motor out of a...
  5. KrisBlueNZ

    DIY turntable build

    Re DC motor speed control, I'm having a hard time finding anything useful as well. Most of it is for BIG motors. A simple approach is just a variable voltage regulator. I'm not sure whether this would be stable enough, because even if you keep the voltage to the motor constant, variations in...
  6. KrisBlueNZ

    DIY turntable build

    Ah! Good. I should have guessed. It depends how the circuit is designed. You'll also need to have a switch for 33/45 RPM. See if you can find a suitable circuit first, and post the URL for me to look at. But I'd look into solving the other problems first, as well as choosing a motor. Making an...
  7. KrisBlueNZ

    DIY turntable build

    You seem to be conflating two separate and independent issues here: the mass of the whole unit, and the mass of the platter. The platter mass affects the agility of the vinyl, and the amount of control you have over it with your hand, where (presumably), lower mass is better, and it also...
  8. KrisBlueNZ

    DIY turntable build

    What, not ALL of it? :-) Yes. Back in the day they used neon bulbs, which would flash at 100 or 120 Hz I guess. The platter had separate markings for 33 and 45 rpm, and in some cases, separate markings for 50 and 60 Hz mains frequencies. These days it's probably done with a crystal-derived...
  9. KrisBlueNZ

    DIY turntable build

    OK I'll start with the easy stuff. There are designs available on the net for phono preamps. Phono preamps are not flat - a specific frequency response called RIAA equalisation is required. For the three-band EQ you can probably find a kitset. The blue light in the linked picture is presumably...
  10. KrisBlueNZ

    DAQ sensor simulator, help please?

    You're welcome :-) Good luck!
  11. KrisBlueNZ

    Wood for the Trees

    Good, the "one step at a time" approach is a good idea. Get a feel for what's possible, and see where that takes you. The design you pointed to looks OK, although 12 bits would be enough (that design uses a 16-bit DAC), but I would use a much better op-amp for the output buffer. The LM358's...
  12. KrisBlueNZ

    Translation and Explanation of Diagram

    sabrehagen, thanks for your kind words about me, but I'm afraid I have to disagree with your rosy interpretation of the reason for, and implications of, the bad English on your remote control receiver (and other cheap Chinese products). The very poor English on the label of your receiver is...
  13. KrisBlueNZ

    LDR circuit ( Application of transistor as switch)

    Yes, the meter must have power supply inputs that can be connected to the power rails of your circuit (you may need to increase this voltage if you can't find a meter that will work from 6V). The inputs to the meter need to be independent of the power supply connections, and they need to...
  14. KrisBlueNZ

    LDR circuit ( Application of transistor as switch)

    Re floating inputs, what Steve means is that your digital meter needs to have differential inputs, not a single ground-referenced input. The meter would have to be powered from the positive and negative supplies of your circuit, and it would have to measure the voltage across the shunt resistor...
  15. KrisBlueNZ

    Voltage Regulator

    That looks good! I would draw the two parallel capacitors separately across the rails, not the way you've shown, but I'm fussy like that. Nice job of listening to suggestions and asking sensible questions :-)
  16. KrisBlueNZ

    4049 hex inverting ic

    Right, as davenn says, we need a schematic, and preferably a photo of your circuit. As well as a description of what you're trying to do. What are you powering the 4049 from? You know it needs power? Also, the inputs of the inverters that you're not using should be connected to a supply pin, to...
  17. KrisBlueNZ

    Voltage Regulator

    The automotive environment is pretty harsh. Every bit of protection and filtering is worthwhile, especially when a failure could strand you somewhere without some important feature working. Different types and value ranges of capacitors have different characteristics. Ceramic capacitors around...
  18. KrisBlueNZ

    Voltage Regulator

    I agree with duke37, I would put a decent sized electrolytic across your 0.1 uF input capacitor. Automotive supply voltages are very noisy and every bit of filtering and protection you can have is worthwhile. Also, your zener diode should probably be a 5W type, just to be safe. If you're worried...
  19. KrisBlueNZ

    4049 hex inverting ic

    The NC terminals are Not Connected, so they AREN'T used! The 4049 is a hex inverting buffer. Each of the six elements inside it has an input and an output, and it drives the output to the opposite logical state from the input ("inversion"). CMOS devices have nominal thresholds of 1/3 VDD and 2/3...
  20. KrisBlueNZ

    DAQ sensor simulator, help please?

    OK I've had a look at the documentation for that DAQ device. The first 18 pins of the first 50-pin IDC connector are used for the 16 analog inputs. Pins 1 and 2 are analog ground, and need to be connected to the ground rail of your external circuit. Each input has a range of +/- 10V relative to...
Top