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  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Recent content by sagor1

  1. S

    Selection Guidelines - Convert DC Wall Wart to AC Wall Wart

    Correct, I was pointing out what linear DC supply to look for in order to strip out the rectification and get an AC supply that would meet the 9.5VAC requirement. Vons found something that worked for him....
  2. S

    Selection Guidelines - Convert DC Wall Wart to AC Wall Wart

    I would suspect any DC wall wart that gives 12.5 to 14.5VDC with no load will do. Getting 0.6A will require a heavier transformer unit, always verify the current capacity. The picture you show, shows a bridge rectifier (4 diodes) in the lower left corner, so most of the clock would run off about...
  3. S

    Home Smoke detectors are all Beeping Batteries are not dead.???

    Correct, many AC detectors are interconnected by a third wire. So if only one detector sees a fault, all detectors will beep the same error code. You need to check all of them…
  4. S

    Selection Guidelines - Convert DC Wall Wart to AC Wall Wart

    To calculate the AC voltage for a wall wart, measure the DC voltage with no load and divide by 1.414. That will give the no load AC voltage. Under the rated load (same load as DC rating) the AC voltage may drop a bit, but not as much as it does at DC mode. Find a power device that gives the...
  5. S

    Saga 1400sv vinyl cutter motherboard issue

    Not much to go on. If there is no power at the red/black plug, then you have to go back to the actual power supply that creates the voltages for those wires. Usually there is some type of fuse in every power supply, you need to check those. So your problem may not be with the motherboard, but...
  6. S

    Can I make two inputs from one??

    If I read the picture of the power adapter correct, it shows output (OP) as AC voltage, not DC. That makes sense if there is rectification farther in the schematic.
  7. S

    DVR not recognising HDD

    R14 may or may not have been installed originally, hard to tell. R2 seems to be feeding D1, which by its symbol, may be a LED. When replacing a HDD in a DVR, you have to initialize/format it with the DVR, using its own formatting menu. That format menu may be hidden in a "tech" menu somewhere...
  8. S

    Computer power supply design

    If the 180W supply is doing what you want, stick with it. One factor about computer PSU is that they all have an optimum efficiency range, usually in the 70-90% of full load. If running at half load, your efficiency "usually" is less, thus producing more heat internally. Thus, unless you have a...
  9. S

    Reclaiming missing motherboard header

    The other question is, does the BIOS know about that header at all. That is, will the hardware actually run the fan if you manage to get it connected. They may have stripped out some hardware code in the BIOS, but that may or may not be true, hard to say for sure. If that box was designed for...
  10. S

    Need help in repairing a dead motherboard

    Did you check F3? It is a fuse that probably feeds some of the power to Q15 and Q14. Remember that the PSU needs a "start" signal (usually the green wire to ground) to in effect turn on. Try a different power supply if possible...
  11. S

    compatible eth ports for laptop

    Why not use the wifi, it is AC4 compatible, which will give good speeds. It may be cheaper to get/upgrade your wifi router to a high end model than trying to fix an ethernet board on a laptop. You can also use a USB hub to expand your USB ports, and then still have one to use a USB to Ethernet...
  12. S

    Lightbox circuit

    Try a different source of music, like your line out from a computer instead of a stereo. Try to isolate if the scratchy sound is due only by being connected to the stereo. If scratchy sound with the laptop as well, then something may not be wired right with the lightbox. If laptop is clear...
  13. S

    Lightbox circuit

    Noise going back to the stereo may indicate improper grounding. Make sure all grounds are connected together between the lightbox and stereo. Don't rely on the LINE out shielding as grounding. I assume you did NOT install the MIC element, as that would pick up noise and just re-amplify it back...
  14. S

    Can I use this charger in every country?

    It is universal input, so it should be usable anywhere in the world, provided the voltage is stable (not some remote generator, etc.) You will need plug adapters for different countries of course...
  15. S

    Circuit behavior

    You are probably drawing too much current from a 9V battery. At 60ma, it can supply enough current to light the bulb. At 160ma, you are maybe drawing too much current and the internal resistance of the battery is causing a voltage drop. As the battery overheats from excessive current, the...

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