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  1. dave9

    replacing two D cells with pair of 18650 batteries but need voltage drop

    Yes, any LDO or other linear regulator, does not "convert" voltages, rather it just shunts excess voltage to ground with the associated waste of power = heat associated with that. Their efficiency depends on how much above the target voltage, the input voltage is, so ideally you want to have...
  2. dave9

    replacing two D cells with pair of 18650 batteries but need voltage drop

    I was assuming you would have a switch between the cells and any type of regulator after them, whether you have to add one or there is a reasonable way to hack an existing mechanical switch on the GC to put the regulation in series after it. At only 90mA drain, it is no contest to me, I'd use...
  3. dave9

    replacing two D cells with pair of 18650 batteries but need voltage drop

    I should have asked what the goal was. If it doesn't need to run long and is tolerant of fairly low voltage, then at a mere 200mA drain, I would just use some LSD (Eneloop, etc) rechargeable AA cells in D-adapter sleeves (since I already have some, though the sleeves, are only a dollar or two...
  4. dave9

    replacing two D cells with pair of 18650 batteries but need voltage drop

    You should charge the cells before connecting them in parallel, or discharge to same voltage level, or very nearly so. However, 0.2V difference is not that much to be concerned about. You should consider them not as 3.7V but rather 4.2V (peak charged voltage) for the purpose of determining if...
  5. dave9

    With respect, in what way would YOU re-use these?

    I would throw them away or recycle if possible, already have my own pile of parts that I'll maybe someday use, BUT that I already have legit purposes for instead of trying to find one. I take that back. If you bought them, then to someone, they must be worth something, so I'd sell them. I'm...
  6. dave9

    Solar lead acid battery housing

    The (now) myth about not storing batteries on concrete floors goes back to when they had wood or metal rather than plastic casings. The moisture that could be present, could either conduct and drain the battery if metal, or swell the wood. Plastic has neither of these problems. I don't think...
  7. dave9

    Wire connection point to point?

    They're usually just referred to as jumper, hookup, or bus wire, typical solid copper core that's tin plated. Sometimes it's called wire wrapping wire or protoboard wire. You can buy kits in different pre-cut lengths but that's really expensive compared to just getting a roll of wire in the...
  8. dave9

    Automatic links

    Owners monetizing the forum. Many of us recognize it is not the poster, just a site script doing it. It causes some visitors to disable all scripts or ambitious ones to isolate which one is the cause then disable that one. It is a precarious balance, add too much !@#$ then it annoys people...
  9. dave9

    Are these helmet headsets salvageable?

    It looks like there was water soluble flux residue left behind after manufactured and it was too damp so that formed conductive shorts, so I would scrub the boards, especially where you see the residue, with hot detergent solution, then soak and agitate, then rinse with alcohol, shake and let...
  10. dave9

    BOSE Solo 10 Help - No Power Up - Pics + PCB Part List

    I don't have all the info specific to this amp in front of me, but if the bridge rectifier doesn't check out, seems simpler to just replace that than to try to devise an alternate PSU you have to tap into the circuit.
  11. dave9

    Diy generator

    The way to stand out is to use the more rational, real-world solution argument which is that instead, the appliances should be repaired and sold and then the proceeds from sales, put towards a product engineered to meet the specific need. We don't live in a vacuum, anything has value and you...
  12. dave9

    Diy generator

    I should have asked a question or two. What exactly does "making a DIY generator from appliances" mean? Does it mean you will be provided with a source of appliances and have to MacGyver something out of what you have in front of you, OR does it mean that all you have to do is make a rational...
  13. dave9

    Diy generator

    Outside the box generator from appliances... Sure, get a carrot out of the refrigerator, dangle it in front of a horse, and let it run on a treadmill with motor reverse wired. ;) You really don't have much headroom here, that if you have to use salvage from appliances all there is from any...
  14. dave9

    12v 2 pin connector

    You might also mention where you're located, since seller location and/or shipping cost can matter. In the US, there are lots of plugs at electronics supplier 'sites like Digikey, where they have a drill-down selector where you pick # of pins, size of pins, pin spacing, voltage and current...
  15. dave9

    Maytag oven

    Have you tried closing the door? ;) What do you consider too long? An old wive's tale is it is supposed to take about 10 minutes to preheat an oven to... something... maybe 400F? Anyway that's the number I've used for years, just let it heat for 10min to follow a receipe cook time or leave...
  16. dave9

    An intro

    Much can be cannibalized from old equipment being thrown away or found at yard sales for practically nothing, including repair candidates, but another way to get a lot of cheap, and sometimes marginal quality parts, is the electronics surplus sites. If you're in the US that could be some like...
  17. dave9

    Diode help.

    ^ Yes many do backfeed, though I couldn't tell you if all do. Some people choose to use the lighter outlet instead, which also backfeeds (and may need the ignition turned on or at least to accessory position to complete the circuit, meaning that other things like the HVAC blower and radio...
  18. dave9

    Diode help.

    Do you have evidence this will work on your specific vehicles? If by "basic 9V" you mean the most common PP3 form factor/size, you might find that not only starting with too low a voltage but that voltage dragged down even further because it struggles to supply enough current. While most...
  19. dave9

    Computer speakers power issue

    Where would you get cables? The internet! Kidding aside, depends on where you're located. A fully made cable might be cheapest on ebay or Amazon while individual connectors, I'd check Digikey, Mouser, etc, electronics suppliers.
  20. dave9

    Different voltage displays on different charge controllers on same battery

    I'd guess that the latter charger is applying current to the battery while taking the reading to result in the 0.2V higher value. You could check this with a multimeter. If it is constantly supplying an extra 0.2V, that could result in shorter battery life long term from trickle charging more...
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