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  1. (*steve*)

    NE5553U - Can't find a datasheet

    This chip is an old (probably obsolete) tracking regulator chip. The only location I can find a datasheet wants me to pay for it. I don't suppose anyone can help find a free version?
  2. (*steve*)

    Off grid house lighting

    A 100W panel should be able to charge the batteries at more than 5A if you use an MPPT charger. These will also (typically) remove the load if the battery voltage falls too far. At a minimum you want to arrange for 150% of the energy taken from the batteries to be replaced each day...
  3. (*steve*)

    Off grid house lighting

    Do you mean 75 amphour batteries? at 12V a 9W bulb draws 0.75 A. 7 of them will draw 5.25 A. A single 12V 75Ah battery will power these for about 14 hours, however that would leave the battery dead flat, and I would not recommend that. two of those batteries will use about a quarter of...
  4. (*steve*)

    MOV blown on NiMH 4xAA cell charger - cause?

    A good MOV should read as a high resistance (or open). Think of them like a zener for AC. A failed MOV typically looks damaged (maybe even blown apart).
  5. (*steve*)

    Voltage Drop and Cord Length?

    Yes, but only for the portion of the load connected to them. For illustrative purposes you could assume that each load is a constant current, and that each length of wire has a small fixed resistance. If you assume this is connected to a constant voltage source, you can then perform some...
  6. (*steve*)

    My new power supply

    Measuring the output voltage of the 100V supply can cause it to drop by 20V (that's 13%!) With the output turned all the way up, measuring the voltage using my multimeter only (151V) And then switching over to the internal voltage measurement... (131V)
  7. (*steve*)

    My new power supply

    I could quote almost everything Hop said. Hey, Hop, were you looking over my shoulder? It's not anywhere near finished yet, and is hopelessly messy, but here is the schematic I've partially reverse engineered from the device. This comes from the wiring under the chassis, there's a bit on...
  8. (*steve*)

    M.O.S.F.E.T. diode clamp

    Marking the body diode as a zener may indicate that the breakdown between drain and source is due to the body diode rather than the channel.
  9. (*steve*)

    My new power supply

    After reading the specs for the 6LS6GCs, it's clear why there's two of them. They have a maximum anode dissipation of 30W.
  10. (*steve*)

    My new power supply

    I'm a sucker for an old piece of hardware... A regulated power supply providing 3 rails: 0-400V 100mA (B) 0-100V 1mA (C) 6.3 VAC 4A It's nicely made, but pretty clearly not a commercial unit. The meters measure either the B or the C output. However there is no deflection of the current...
  11. (*steve*)

    Battery Insulation resistance Caluculation [Software code ]

    This observation may not apply to @janybasha but I have made it on my many trips to India that there are a vast number of people with masters degrees and higher who don't have any practical experience. The issue is that there is a larger opportunity for education than there is for gaining...
  12. (*steve*)

    Advice about MC34063 based buck converter diagram

    It probably won't make much difference unless you're dealing with low level or analog signals.
  13. (*steve*)

    Battery Insulation resistance Caluculation [Software code ]

    R = V/I
  14. (*steve*)

    Replacement Optical Isolator

    Here is another place you can get those neon vactrols http://www.surplussales.com/Guitar-Amp-Components/Guitar-amp-components.html
  15. (*steve*)

    Replacement Optical Isolator

    It would be really great if you can find a source for this part, but at least it's something that you can cobble together a replacement. There's lots of stuff that while once common is now extreme unobtainium. The problem is that the drive requirements are so different. If we had access to...
  16. (*steve*)

    Replacement Optical Isolator

    Now I'm not looking at the datasheet on a tiny screen I can see it's a neon. Aaagh! How often do neon bulbs fail over time? -- if it was a filament lamp, then I'd bet the failure was there.
  17. (*steve*)

    Replacement Optical Isolator

    Or open up the existing one and replace the bulb (the most likely failure). If this operates from DC, you might get away with a white led and a suitable series resistor (that you might have to determine by trial and error). Make sure you seal it up if you take this approach. You don't want...
  18. (*steve*)

    Adjustable current souce 12Vin 400mA o/p 32W

    To pass 400mA through a 200Ω resistor you'll need to apply 80V. That's a bit more than 6V. If you use a boost converter to create 80V (practically you'll need a little more) then your 6V battery better be capable of a 6A current. Once you have a sufficient voltage, a simple 2 transistor...
  19. (*steve*)

    Comedy Thread

    Go on, order a single resistor. I dare you.
  20. (*steve*)

    about cable gauge

    They have two purposes. The first is to help prevent the voltage from sagging when brief high current pulses are drawn. The second reason is that the long cable run can have significant inductance, and it is possible that you will see even greater voltage variations sure to this. Additional...
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