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  1. KrisBlueNZ

    How to create a HEX file for 8085 processor along with 2732A eprom

    He may not have written the code himself and he may not be able to translate it from the 8085 to the 8051 architecture. They are quite different you know. The 8051 doesn't have the resources that the 8085 has. It cannot address RAM directly using direct 16-bit addresses and multiple pointer...
  2. KrisBlueNZ

    Battery question

    Yes, because they are never 100% efficient. But you need to get your terminology clear. A battery stores energy, not power. Energy is measured in joules, and one joule is the amount of energy transferred when one watt of power flows for one second. Take a typical rechargeable cell such as...
  3. KrisBlueNZ

    Stage Line 500W amp repair project

    OK thanks for that. I'm only interested in the voltages at the marked points. So if I've indicated a wire that goes to the base of a transistor, just measure the base. Those voltages in the bottom half of the circuit should be negative! Can you also measure the voltage across R20, and the...
  4. KrisBlueNZ

    What is this microswitch called (replacement needed)

    Hmm. Good luck!
  5. KrisBlueNZ

    Stage Line 500W amp repair project

    Aha! They're not transistors; they're triacs. They're a special type of semiconductor that is used to "crowbar" a circuit if a fault is detected. There's one for each channel, connected between the output and the 0V rail. If a fault is detected, the triac is triggered, and it puts a big fat...
  6. KrisBlueNZ

    Word Clock circuit help

    It sounds like it might be a separate problem. Does the Arduino run properly with nothing at all connected to it? BTW, to clarify: You can (and should) power your CD4094s from the 5V supply from the Arduino, but the LEDs need a separate supply. The negative sides of the two supplies must be...
  7. KrisBlueNZ

    What is this microswitch called (replacement needed)

    Hi Mike and welcome to Electronics Point :) That's an odd username to choose if your name is Mike... That looks like a "tact switch" aka "tact button". They're used for front panel pushbuttons on appliances. They're not designed to be stomped on though. I hope the pedal doesn't put the full...
  8. KrisBlueNZ

    Dumb question re. simple inverter

    Every IC should have a decoupling capacitor, typically 0.1 µF multi-layer ceramic, connected as closely and directly as possible between the positve supply pin and the 0V pin. On logic ICs these are pins 14 and 7, or 16 and 8.
  9. KrisBlueNZ

    Word Clock circuit help

    OK, I think you're going to need a higher voltage supply for the LEDs. The ULN2003 ICs that are driving the LEDs have a VCE(sat) voltage of about 1V. In other words, their outputs pull down to about 1V above the 0V rail. The LEDs typically need let's say 3.2V. That adds up to about 4.2V. Using...
  10. KrisBlueNZ

    Word Clock circuit help

    What type of LEDs are they? Do you have a part number for them? If not, can you measure the voltage across one of them when it's illuminated? Can you confirm the resistor value is 10Ω? It is important! What is the maximum number of LED+resistor combinations that are connected in parallel and...
  11. KrisBlueNZ

    Word Clock circuit help

    Hi Craig and welcome to Electronics Point :-) Have you used resistors in series with the LEDs to limit the current? If not, you need to. Try something like 220Ω in series with each LED to start with. What kind of LEDs are you using? Can you show the full wiring for one of them as an example...
  12. KrisBlueNZ

    PAM clarification

    Right, it would. But why discharge the capacitor? AFAIK the capacitor is only needed to hold a steady voltage for the ADC to convert. I can't see any reason to discharge it. Can you see any explanation of why the capacitor is discharged?
  13. KrisBlueNZ

    Panasonic PT-53TW54J (BP832) TV fault

    Hi there and welcome to Electronics Point :-) I haven't been able to find a service manual for that model, and that makes it hard to proceed. Can you describe the sound it makes?
  14. KrisBlueNZ

    PAM clarification

    In PCM, the analogue signal is sampled and converted to digital form at regular intervals using an ADC (analogue to digital converter). A sample-and-hold circuit may be needed at the input of the ADC depending on the type of ADC used. I can't see any reason for the "discharge switch" and the...
  15. KrisBlueNZ

    Resistor

    The yellow band obviously means something. It could indicate ±25 ppm/°C temperature coefficient. I don't know whether those old 5% carbon types were ever marked with their temperature coefficient though; it seems a bit irrelevant when the basic tolerance is only 5%. But the temperature...
  16. KrisBlueNZ

    Zener Diode identification (color bands)

    The "SA" in the circuit reference "SA101" could stand for Surge Arrestor.
  17. KrisBlueNZ

    Designing a Time Delayed Relay

    Maximum currents in the mains transformer are a few hundred milliamps. The current is inherently limited by the transformer design; see post #249: https://www.electronicspoint.com/threads/designing-a-time-delayed-relay.268425/page-13#post-1632350
  18. KrisBlueNZ

    Capacitor Part #

    Any of these: http://www.digikey.com/product-search/en?FV=fff40002%2Cfff80009%2C3400fd%2C402e23%2Cfc01ac%2C1140050%2C2dc0051&ColumnSort=1000011&stock=1&quantity=1&pageSize=250
  19. KrisBlueNZ

    555 monostable help

    OK, I had a think about this and here's the circuit I came up with. The circuit produces a pulsed closure of the relay contacts after about five seconds of being powered up. The pulse is about half a second long. After power is removed, power must remain OFF for about 30 seconds, otherwise it...
  20. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    Obviously you can't provide details on those cores. This means you're taking the wrong approach. You need to get some cores that come with proper documentation. I think NXP have a good range of ferrite components. At my previous job, we used a lot of NXP 3C80 gapped cores for switching...
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