Search results

  1. Old Steve

    Help making a CRT oscilloscope

    If you keep trying coils with low inductance and low series resistance, soon you won't have a TV to turn into an oscilloscope. :( duke37 recommends ferrite, so forget the powdered iron. They were just for example purposes. The pot core might be worth buying for a test, if it's ferrite, but you...
  2. Old Steve

    Help making a CRT oscilloscope

    Just looking at RS, the datasheet for the first ferrite toroid I looked at has the relative inductance mentioned, so it's not such an archaic term after all. :D It actually mentions the relative inductance for the same coil in different materials. It's only 25mm diameter, so probably not big...
  3. Old Steve

    Help making a CRT oscilloscope

    You won't be able to do that in the shop. It requires winding a coil on the core if the relative inductance is not already known. None of the ones at Jaycar that you showed are suitable, I should say. Relative inductance seems to be an archaic term now - I can't find reference to it anywhere...
  4. Old Steve

    Help making a CRT oscilloscope

    Thanks for helping out. I really had no idea what sort of core, except that iron was often used for low frequencies. I didn't think steel was a good idea, either. After originally saying I couldn't help with the coil design, I found myself being drawn in further and further. Separate series...
  5. Old Steve

    Help making a CRT oscilloscope

    Iron might be better than steel, but I'm not 100% sure. Iron is commonly used, but I've never heard of steel being used. It would have different characteristics. And first double-check that the original is an iron core and not ferrite or similar, in case I'm wrong. (It won't be steel.) The...
  6. Old Steve

    PWM led without timer

    Again, post your code. I'm working in the dark here.
  7. Old Steve

    PWM led without timer

    As an alternative, with the later chips, you can toggle pins like this, too:- PINB = 0x5A; // This toggles pins 1,3,4 and6. (Every bit that is set toggles the corresponding pin.) rather than like this:- PORTB=PORTB ^ (1<<pin); // Toggles pin. (This will work in both old and new chips.)
  8. Old Steve

    PWM led without timer

    No, it seems that pins can't be accessed in AVR Studio as easily as they can in PICBasic Pro and Arduino. I had a PIC doing exactly what you want many hours ago, running the PICBasic Pro code I posted. This is what I've come up with so far in AVR Studio. You need to include "delay.h". You'll...
  9. Old Steve

    Technics RS-TR313

    You never know. ;)
  10. Old Steve

    what mosfet to use for an induction heater

    My money's on RS too. I placed an order on Monday night, the parts that were in the country were dispatched Tuesday and I got them Wednesday, then got the parts that they said were only in stock in the UK today. Pretty good. :)
  11. Old Steve

    sample and hold pulse source?

    I hadn't thought of that. :oops:
  12. Old Steve

    Where would I Get My Hands On....

    If you want a lack of light, why not just block the light source to the room, only allowing a tiny, adjustable bit of light in? For this, using a lamp to add light, you'd already need to blacken the room totally anyway. Otherwise, a standard dimmer, with a very small bulb in a fully enclosed...
  13. Old Steve

    sample and hold pulse source?

    That's OK, one more 4069 gate cures that. And I'm obviously still pretty rusty - should have thought of suggesting two inverting gates with added hysteresis resistors. I've done it myself in the past, long ago.
  14. Old Steve

    PWM led without timer

    I have the avr-gcc compiler here too, in the Win-AVR package, but haven't even got as far as working out how to install it all properly yet. I struck makefile problems. Been too busy with other stuff. Let us know how you go. The microseconds method is best, for a visibly smooth fade. I just...
  15. Old Steve

    Help making a CRT oscilloscope

    Gus, can you tell what the original core was made from? My guess would be iron, for that frequency range. I can't mentally picture what the core of those coils was made from. The shape won't be too critical. I mentioned the wire gauge and the steps needed in post #5. First, determine the...
  16. Old Steve

    what mosfet to use for an induction heater

    Here's that full-sized image back:-
  17. Old Steve

    sample and hold pulse source?

    Without a Schmitt trigger, the output can oscillate at the threshold with slow-changing or noisy inputs. The hysteresis of a Schmitt trigger stops that. It's ideal for the purpose. But you could try a 4069 and see how it goes.
  18. Old Steve

    what mosfet to use for an induction heater

    I couldn't say, Rick. I've never dealt with element14. You might be lucky, but most suppliers only use Australia Post. Mind you, element14 might have an option for courier delivery, but I doubt if it's free. Update: I just checked the element14 website: (If your order is less than $45, it's...
  19. Old Steve

    PWM led without timer

    And since I took the trouble to write and test it, so it's not completely wasted, here's the PICBasic Pro version:- TRISB=%11111000 ' Output to LED1 on RB0, ' output to LED2 on RB1, ' output to LED3 on RB2, ' others unused...
  20. Old Steve

    PWM led without timer

    If you want to improve smoothness, so the eye can't see the steps so easily, and you can get microsecond timing, you could try this. (I wrote and tested it in a PIC chip with the PICBasic Pro compiler, then converted it to Arduino, so you'll need to convert it to suit your compiler. It shows...
Top