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  1. S

    Is it possible to replace keyboard LEDs with neon indicators and a single inverter?

    Are there opto-isolators which work with AC? If there are, would it be cheaper anyway to combine DC opto-isolators with a triac? Here's opto-coupling triacs.
  2. S

    Is it possible to replace keyboard LEDs with neon indicators and a single inverter?

    Thanks for everyone's responses. The keyboard is not valuable so I don't mind risking its destruction for my project. I want to drill holes in the keyboard for the lamps to protrude out of the case. I have designed this circuit which reroutes the output of the inverter to a resistor when the...
  3. S

    Is it possible to replace keyboard LEDs with neon indicators and a single inverter?

    I want to modify my keyboard for a retro cyberpunk look and replace my LED (scroll, caps and num lock) indicators with neon indicators. I can power a neon lamp from a low voltage using a laptop CCFL inverter but I was wondering if there's any way I could power three from one inverter. They...
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    Spurious voltage readings for open transistor

    I have a circuit I made for an experiment with four LEDs in series behind a transistor with a floating base so the circuit is open and LEDs are unlit. When I measured the voltage across the LEDs I got a stable value of about 2.4 V but when I measure the voltage across the collector and emittter...
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    Adding keys to an old PS/2 keyboard?

    I found five locations in the matrix which are not used by the keyboard but do send scancodes to the PC! All I did to find them was connect my keyboard to the PC and use a breadboard jumper cable to connect the solder pads sequentially, using a keyscan program to record the results. I compared...
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    Adding keys to an old PS/2 keyboard?

    I have an AST KB-102 keyboard but it doesn't have Windows or context menu keys. Is it possible that I could add a couple of switches to the surface of the board and then wire them up into the matrix so they will give useful scancodes to the operating system?
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    Connecting two batteries to one phone through the case

    Why mention the thing that makes no sense though? Regarding charging, I don't see a problem either. The current is going to be limited by the supply and each battery will get less than it would if there was a single battery.
  8. S

    Connecting two batteries to one phone through the case

    I don't see how that's a problem. The good battery is doing all the work right now so anything less than that is clearly not an issue. I live in a country with socialised medical care but it's irrelevant because batteries don't explode for no good reason and I don't believe that what I've...
  9. S

    Connecting two batteries to one phone through the case

    Thanks for your response. Given that my phone stays in my pocket, a solar panel is not an applicable solution for me. What is the problem with dissimilar age batteries being connected in parallel? I thought balancing issues only applied to batteries in series? What is a "canteen" in this context?
  10. S

    Connecting two batteries to one phone through the case

    My Samsung Galaxy S5 is a little old and I would really like to augment the aging battery by connecting my old battery in parallel with my even older battery. I could just buy another new battery but that will only get me a relatively small improvement and this solution uses what I have already...
  11. S

    Making a floodlight from the CCFLs from many broken monitors - need >1.2A, 700-1000V inverter

    I've had a look at the back of a monitor that says it draws 0.7 A at 240 V. What translates to 168 W which is more than I was expecting. Assuming that the four built-in CCFLs use 8 W each, that would still leave 136 W. Assuming the power supply is only 60% efficient that leaves (168 W x 60%) -...
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    Making a floodlight from the CCFLs from many broken monitors - need >1.2A, 700-1000V inverter

    That's what I'm already suggesting. I will use the board from the desktop monitors to power their respective CCFLs and then use the 5V and 12V outputs from the same desktop monitors to power the laptop inverters. I can't easily cut off the excess desktop monitor circuitry so I might as well put...
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    Making a floodlight from the CCFLs from many broken monitors - need >1.2A, 700-1000V inverter

    Thanks for replying. I think I will persist in trying to use their own circuit boards. I don't mind that the CCFLs are fragile since they're going to be mounted inside a protective housing. The screens all came to me for free because they're broken and not worth repairing. I took a close look...
  14. S

    Making a floodlight from the CCFLs from many broken monitors - need >1.2A, 700-1000V inverter

    I want to build a floodlight by combining the CCFLs of many broken LCD monitors (laptop and desktop) The laptops come with nice, compact inverters which I can re-use relatively easily but the desktop screens use massive circuit boards with a load of unrelated stuff which I think is too bulky...
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    Repairing a CFL that stopped working after a few hours of use

    A long time ago I bought a multipack of CFL bulbs and I no longer have the receipt. I put one of them into service and after a few hours of use (and about three ignitions) it has stopped working. I've opened it up and I see nothing obviously wrong. What parts can I test? How many hundreds of...
  16. S

    Seeking help reverse engineering laptop screen inverter sans datasheet

    Correction: ENABLE pin can be left disconnected because it's tied to VCC somewhere therefore on by default.
  17. S

    Seeking help reverse engineering laptop screen inverter sans datasheet

    Okay, as I suspected black is GND and pink is VCC (I used 12 V). Blue is ENABLE and needs 2-6 V to come on and yellow is DIM (0 V is max brightness and increasing towards 2 V causes the CCFL to dim and eventually flicker erratically; I'll be tying it to ground).
  18. S

    Seeking help reverse engineering laptop screen inverter sans datasheet

    Does this image make it any clearer what candidates may be VCC and GND?
  19. S

    Seeking help reverse engineering laptop screen inverter sans datasheet

    I have a few inverters from broken laptop screens (Dell Latitude LS model) and there are no datasheets that I can find for the controller IC (3972 OAW). There are only four input pins for the inverter board and I think that it might be possible to figure enough out to connect it to power without...
  20. S

    What way around are these voltage regulators?

    Thanks very much, guys! I'm a reverse engineer! :P I'm trying to use the inverters of some laptop monitor CCFLs (I got about 15 different ones for free) to make a free bright light. A lot of the inverters I can find no information for but there are a few for which I can. I might resort to...
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