Search results

Search Forums New Posts
  1. KrisBlueNZ

    Two atmegas from the same oscillator?

    That design shows an oscillator module, yes, but you can make a Pierce crystal oscillator with a single gate, two resistors, two capacitors and a crystal. You can then buffer that oscillator with another gate, feeding two gates as shown. So you can do it all with one IC. But the IC can't be a...
  2. KrisBlueNZ

    MOSFET connected in phase opposition

    The PWM signal on pin 49 controls Q2. I think there's at least one error in the circuitry between this input and Q2. The duty cycle (or the inverse of the duty cycle, depending on the error(s)) determines the amount of time for which Q2 is ON, which determines the voltage at the output of this...
  3. KrisBlueNZ

    Arduino stepper code for ULN2003

    You can use the vBulletin CODE and /CODE tags (with square brackets around them which I can't show within this post, obviously) to delimit a block of code in your posts. This shows it in a monospaced font, in a box, without stripping the whitespace. Here is some code
  4. KrisBlueNZ

    Equation to figure out the resistance to charge capacitors evenly

    Yes, I assume it was just a simplification and approximation to put the discharge into context with his other calculations.
  5. KrisBlueNZ

    Fender 3 spring reverb tank

    Is that circuitry built into it? If so, it's very easy to use. Just feed an audio signal in the input and connect an amplifier to the output. The "clipping" LED will light if the signal amplitude is too high. It also requires a DC power source. The voltage range is not shown on the schematic...
  6. KrisBlueNZ

    Equation to figure out the resistance to charge capacitors evenly

    Bob Pease uninformed? Edit: In response to the original question. The problem of uneven charging of multiple capacitors only happens if they are connected in series. It is often solved by connecting a resistor across each capacitor (resistor values are the same if capacitor values are the...
  7. KrisBlueNZ

    LEDs in parallel

    I had a quick read of the article. It is poorly written and it's not clear who the target audience is, but it does explain the issues fairly well. My overall response to the whole matter is to ask why LEDs are connected in parallel at all. Unless the number of LEDs is huge (hundreds or more)...
  8. KrisBlueNZ

    MOSFET connected in phase opposition

    Yes, Q1 and Q3 drive opposite sides of T1 and must be enabled alternately. There are several ways to generate the signals shown in your oscilloscope trace. If the microcontroller clock frequency is high enough and the microcontroller has an internal timer with two "output compare" circuits...
  9. KrisBlueNZ

    lighting a 7 segment LED

    Have a look at Digikey's LED range sometime, sorted by colour. There's actually quite a lot of variation in forward voltage for a given colour, even within the "indicator" category. It's very straightforward. So: +12V to anode of segment. Cathode of segment to drain of N-channel MOSFET. Source...
  10. KrisBlueNZ

    Rewiring 7-band EQ

    Yes that should be fine, as long as the cable is long enough.
  11. KrisBlueNZ

    lighting a 7 segment LED

    You don't need a separate MOSFET for each strand. Each "strand" of five LEDs in series needs its own current limiting resistor in series with the five LEDs, as you said. Then each segment can be made into a two-terminal unit by connecting the four strands in parallel. This makes each "segment"...
  12. KrisBlueNZ

    The magic of Colloidal silver

    Excellent explanation Bob!
  13. KrisBlueNZ

    Roland FD-8 Hi-Hat Control Pedal

    It could be a pressure-sensitive resistor: https://en.wikipedia.org/wiki/Force-sensing_resistor If the sensor itself is faulty you should be able to see some visible signs of damage. You should get a genuine replacement part from a Roland service agent. Look at the blurb that came with the...
  14. KrisBlueNZ

    lighting a 7 segment LED

    Normally I agree that the OP should have posted a schematic right at the start of the thread. I replied with a generic and (hopefully) complete list of possible reasons for this problem so that my reply will be immediately useful to others who find this thread in future because they have the...
  15. KrisBlueNZ

    2.0 to 3.0 desk speaker EQ mod

    Right. If the power amps have any significant output power, they will probably run from a relatively high voltage - 20V or more. You can drop this down to a lower voltage to suit your op-amp-based circuitry using a three-terminal linear regulator e.g. a 7815 (15V output). If your amplifiers...
  16. KrisBlueNZ

    Rewiring 7-band EQ

    Right. I guess the power cord currently comes into the power amp chassis. That's where you should connect the earth wire, and the shields of all the signal cables will propagate the earth to the chassis of the other modules. I guess the ideal connection for the +12V and 0V wires from the wall...
  17. KrisBlueNZ

    lighting a 7 segment LED

    See post #6 on this thread, item 3.
  18. KrisBlueNZ

    lighting a 7 segment LED

    Code != schematic
  19. KrisBlueNZ

    HP 1741A Oscilloscope

    OK, it looks like the +156V DC rail is created by adding voltage to the +120V rail, so 60V AC across 14 and 15 is probably right. It's really hard to be sure because the markings on the schematic are not really readable. So the +48V and +120V rails are far too low. I would start with a careful...
  20. KrisBlueNZ

    lighting a 7 segment LED

    I agree that it would be useful to see the schematic. My comments are based on all the possible mistakes I could think of that someone could make when connecting one or more seven segment displays to a microcontroller. It's up to the OP to read my comments and figure out which mistake(s) are...
Top