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  1. KrisBlueNZ

    8051 specification

    The 8051's code (ROM or Flash ROM) bus is 8 bits wide. That means that every instruction must be a multiple of 8 bits in size. For simplicity, the designers decided that every instruction would start with an 8-bit opcode, which is passed to the instruction decoder to determine the type of...
  2. KrisBlueNZ

    check the circuit

    Try again using only decimal numbers. Do you mean 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, ...? What does "mod 5" mean to you?
  3. KrisBlueNZ

    Will an AOC - 23.6" LED HD Monitor work with my OLD PC?

    The Dell specification sheet for the GX620 doesn't state the maximum graphics resolution, but the sheet for the GX745, which uses the Intel Graphics Media Accelerator 3000 (which is part of the Q965 chipset) states a maximum resolution of 1920x1200. It doesn't state a frame rate, nor whether...
  4. KrisBlueNZ

    Positive and Negative regulators sections are different

    The voltage offset is about 6.2V. R56 causes current to flow in the zener diode. This causes a fixed voltage to appear across it. This produces the voltage offset between VOUT and the transistor's base. They are not using the current sensing input as the negative regulator's input. They are...
  5. KrisBlueNZ

    Positive and Negative regulators sections are different

    Yes, it provides a fixed voltage offset. This makes the transistor's base more negative than the output of the regulator IC while still allowing the regulator IC to control the transistor. Read the 723 data sheet and draw up the negative regulator circuit from the point of view of how the 723 (a...
  6. KrisBlueNZ

    Positive and Negative regulators sections are different

    It creates an offset voltage, yes. Without it, the circuit wouldn't work because the voltage at the VOUT pin doesn't go far enough negative. I haven't looked into the design in much detail and I'm not very familiar with the 723. Have a look at the data sheet and see if you can figure out how...
  7. KrisBlueNZ

    Positive and Negative regulators sections are different

    The differences are due to the fact that the µA723 regulator IC is designed to operate as a positive regulator. The +15V regulator shows how the 723 is supposed to be used. The pass transistor (Q21) is driven directly from the VOUT pin, and the load current is sensed across R57 and passed back...
  8. KrisBlueNZ

    IH5011 Fet switch , virtual ground switch?

    Can you provide a link to a data sheet?
  9. KrisBlueNZ

    check the circuit

    So what should the whole pattern be? What comes after 7? Then what? Can you list the numbers, in sequence, the way I did?
  10. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    You'll need to cut it to be able to use the voice changer with it, so you might as well do it now. See if you can make the cut close to R8 and scrape some of the solder mask off the track so you can connect across the break with a blob of solder, so you can return the amp to its original...
  11. KrisBlueNZ

    check the circuit

    Modulo 5 means that the valid output values are 0, 1, 2, 3, and 4. Since it's a down-counter, those numbers appear in reverse order. So the output pattern should be 000 (0); 100 (4); 011 (3); 010 (2); 001 (1); 000 (0); 100 (4); 011 (3); 010 (2); 001 (1); 000 (0) etc. Do you agree?
  12. KrisBlueNZ

    check the circuit

    OK. First you need to mark the outputs on the drawing. It may seem obvious to you that AQ, BQ and CQ are bits 0, 1 and 2 of the output, but that's no excuse for not showing this information explicitly. You also need to indicate whether the preset inputs are active high or active low. Without...
  13. KrisBlueNZ

    Combining an Amplifier with a Voice Changer?

    A good way to cut tracks is to cut a V into the board. Cut directly across the track, but with the scalpel slightly twisted so the cut doesn't go vertically into the board. Then make another cut next to that cut, with the scalpel twisted at the opposite angle. The cuts will meet at some point...
  14. KrisBlueNZ

    what does incision in a board layout mean?

    I don't know. I used to do it by providing a complete path for the routing bit, using a track of a designated thickness on a designated layer. The PCB manufacturer would use that layer to set up the routing bit path. I think you would have to work with your PCB manufacturer to explain what you...
  15. KrisBlueNZ

    Solid State Trigger Coil Simulator

    I get it. So the first two traces are from real inductive pickups? You can kind of imagine the magnet attached to some rotating part of the engine, approaching the pickup, generating the rising edge getting steeper as it gets closer, then over a short time period, passing the pickup coil...
  16. KrisBlueNZ

    what does incision in a board layout mean?

    I guess they're referring to cutouts that go all the way through the board, to increase creepage distance. These are commonly used where high-voltage isolation is needed. I believe they're obtained by passing a router bit through the board and moving it round, as part of the routing process that...
  17. KrisBlueNZ

    Assistance connecting electonic kick drum to drum machine

    I found a helpful Wikipedia page at https://en.wikipedia.org/wiki/Roland_V-Drums. Please have a look at it and let me know if it tells you anything that sounds useful. According to that article, the HD-3 "brain" (drum sound module) uses a custom connection to all the pads and pickups. Are you...
  18. KrisBlueNZ

    Mosfet Selection....

    RDS(on) vs. VGS was all that I was interested in at the time. Yeah, that's what I do. If you find the easy button, please let me know too!
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