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  1. KrisBlueNZ

    Decoding 433.92mhz remote?

    I can't read the markings on the big IC. Can you post them?
  2. KrisBlueNZ

    Decoding 433.92mhz remote?

    I think Adam meant pictures of inside the remote, so we can see what components it uses.
  3. KrisBlueNZ

    Mosfet bridge safety

    Are you driving the gates of all six N-chanel MOSFETs from outputs of the LMC6484 that's powered from 11V? If so, that won't work; the high-side MOSFETs need a gate voltage quite a bit higher than the positive supply rail because when they conduct, they pull their sources up to +12V and you need...
  4. KrisBlueNZ

    Dynex DX-L42-10A Intermittent Issues

    I told you twice how to get the right replacement. The LM1117 is only rated for 0.8A. But let's assume it will be OK. You can replace it later if it isn't. Yes it seems that N603 provides the MST3.3V rail. If its output is 3.3V but the input voltage on the right hand pin of N604 isn't, then...
  5. KrisBlueNZ

    Capacitive Reactance Circuit

    No; they take far too long to heat up. An inductor would help, but a suitable one would be big and heavy.
  6. KrisBlueNZ

    Capacitive Reactance Circuit

    Yes that's true. At high frequencies, both caps will have reactances so low that most of the interference will be dropped across the input resistor, but the rest will be split between the two capacitors, and most will still flow into the bridge. I tried splitting Rin into two 150Ω resistors...
  7. KrisBlueNZ

    Fluke 199B Scopemeter Repair

    Yes, he said he connected the battery backwards.
  8. KrisBlueNZ

    12V Lead Acid/Sealed Lead Acid Battery Charger

    I designed an SLA charger once, for 12V 6.5 Ah batteries. It used a buck switching regulator and had a maximum charge current of 1.5A. To charge a 100 Ah battery at an equivalent rate you would need a charger with a maximum output current of 23A! You should decide on your maximum charging...
  9. KrisBlueNZ

    Fluke 199B Scopemeter Repair

    Steve, he seems to have identified it as R4101, 0.15Ω ±1% TC70 (presumably ±70 ppm/°C). See the asterisk on the parts list in post #11. Yes it is a current shunt. It's in the top left area of the schematic in post #3. There is no diode connected directly across the battery; the fault current...
  10. KrisBlueNZ

    Fluke 199B Scopemeter Repair

    OK, on the battery connector, pin 1 (presumably the left end on the photo in post #1) is positive, and pins 2 and 4 are negative. The damaged component seems to be connected directly between pins 1 and 2, but I don't see any component on that schematic diagram that's connected directly across...
  11. KrisBlueNZ

    Capacitive Reactance Circuit

    That depends on what you mean by "overpower". Obviously, the interference current will split 50/50 between them when its equivalent frequency is ten times the mains frequency, or more. That's why I chose a rise time of 1 µs for the interference. I think so. For an LED driver, where everything...
  12. KrisBlueNZ

    Capacitive Reactance Circuit

    You would expect to see that if the disturbance was at 60 Hz, yes. But my disturbance had 1 µs rise and fall times!
  13. KrisBlueNZ

    Switching loads using Raspberry Pi

    You have missed LOTS of things! I can't get into it right now. But Google "common emitter" and "common collector" and learn how both configurations work. They both use a bipolar junction transistor, but that's about the only thing they have in common!
  14. KrisBlueNZ

    ultrasonic leak detector

    I posted a schematic with two alternative designs for a constant-frequency 40 kHz ultrasonic transmitter at https://www.electronicspoint.com/threads/automatic-doorbell.270436/#post-1624785 Not sure whether your transmitter uses a single, constant frequency or not. Post some pictures of it if...
  15. KrisBlueNZ

    Switching loads using Raspberry Pi

    Cool :-) The emitter follower (aka common collector) and the common emitter configurations actually use the transistor in quite different ways. Each one has advantages, but when you want to switch a higher voltage with a lower voltage, the common emitter saturated switch is the configuration to...
  16. KrisBlueNZ

    Switching loads using Raspberry Pi

    What you have there is an emitter follower. The emitter will "follow" the base voltage, with a voltage drop of about 0.7V. So when the base is at +3V, the emitter will be at about +2.3V, which may not be enough to light the LED. The normal way to drive an LED is using a common emitter saturated...
  17. KrisBlueNZ

    decoder for 8051

    Address buses will be outputs from the instruction execution unit (IEU) (which includes the instruction decoder) to the other components of the CPU core. That's because the IEU needs to tell the program memory, or the data memory, which location it wants to read or write. The data bus to the...
  18. KrisBlueNZ

    fairchild mosfet taken from Mean Well TN 1500 inverter.

    Hi there and welcome to Electronics Point :-) The 12N60 is an N-channel power MOSFET. It's available in several different packages, with slightly different specifications. The basic specifications for the biggest package are: Drain current 12A (48A peak) (max allowed) Drain-source voltage 600V...
  19. KrisBlueNZ

    decoder for 8051

    No. That's a total of 8+4+1+2+4+1+1 = 21 signals. There is no reason to use a decoder with them. What are you trying to achieve?
  20. KrisBlueNZ

    Fluke 199B Scopemeter Repair

    It's hard to say; there's not much of it left! It could be a diode for reverse battery protection. If it has disintegrated, it would have failed to protect the rest of the circuit, so you may find lots of damaged components, if you connected the battery backwards. What did you do to cause this...
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