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  1. Externet

    Magnifying lens help needed pls.

    I suggest you forget about magnifying glasses/lenses, you may end hating it. Get a 'bullet' NTSC surveillance video camera, available cheap. Screw-in a 16mm lens. Get a NTSC to VGA video converter if your monitor/TV does not have composite video-in. Attach to a desk lamp that had the magnifying...
  2. Externet

    building a HF transceiver

    :) ----> https://en.wikipedia.org/wiki/Citizens_Band_radio_in_India
  3. Externet

    Anyone fancy designing a schematic?

    The schematics are usually in the data sheet application notes of the integrated circuits used, if not provided with the item. ----> https://www.adafruit.com/product/3072 ---->...
  4. Externet

    building a HF transceiver

    If you already had such transceiver among your things, you would not build it, right ? Well, if you can settle for a couple of Megahertz less; there is plenty of them at yard sales, toy stores, pawn shops, ebay, for a hundredth the cost of gathering all the parts -quantity one- in a thousandth...
  5. Externet

    Electronic trip wire / alarm

    For " a total newbie", getting ALL the parts for a proven/tested design, better pick a flavor of choice : ----> https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20170720054331&SearchText=entry+announcer+chime+beam Then dismantle it to pieces while reverse-drawing its diagram. Now...
  6. Externet

    Maximum battery charging using small generator idea

    And a lead acid battery cannot absorb dozens of Amperes by itself on recharging. It will 'boil' and get destroyed. Only many of them in parallel may. Lead acid batteries are to be charged on constant voltage near 14V., not dumping countless Amperes into them. At 14V, they will take/accept...
  7. Externet

    Maximum battery charging using small generator idea

    Better not abusing your generator. A 700W+ expensive variac will not raise Watts; only Volts, at the expense of current and with the variac losses insertion added. A battery charger capable of 700 Watts would be the maximum improvement to shorten time.
  8. Externet

    Activating a pump based on water flow

    OK, understood. The washing machine shuts down the flow when filled and that should stop the pump. If your existing 'normal pump' does not stop on pressure, go ahead with the flow sensor. Extra suggestion off topic: Remove the hose attached to the washer machine end and check for debris...
  9. Externet

    Activating a pump based on water flow

    Be aware of details... To activate a pump when there is flow... When the pump is on, water flows and tells the pump to keep running ? How will it shut off ? Only when demand faucet closes ? Consider a pressure commanded pump, like ---->...
  10. Externet

    Finding equivalent semiconductors -any websites?

    Not exactly for hard-to-find; but here is one : ----> http://nte01.nteinc.com/nte%5CNTExRefSemiProd.nsf/$all/72BF14B50722ACF285257910007E5A0D?OpenDocument
  11. Externet

    Replacing light bulbs with LED's for illuminating a radio's scale

    AC reaches peaks (and valleys) of 1.41 times RMS = 14.1 Volts. for the 10 Volts AC. Nothing wrong with asumming 10% extra if secondary of transformer puts 11V AC RMS instead. That raises peaks to 15.5 V. Call it 16V for safe calculation. The 16 V when used with three 3.33V Vf LEDs leaves...
  12. Externet

    2 Portable generators

    Hmmm... Are the neutrals of both generators joined together to the house neutral ? Is there a possibility the neutral used for the computers reaches path -say internally to the printer , or UPS- into a wall outlet ? I would start disconnecting things one by one until the misbehavior...
  13. Externet

    Motion sensing mouse trap

    These did not fail in my previous location: ----> http://www.ebay.com/itm/JT-Eaton-409-Jawz-Plastic-Mouse-Trap-for-Solid-or-Liquid-Bait-2-Pack-/232079019484?epid=1900190015&hash=item3608fccddc:g:zHEAAOSw6DtYWZrH And are available at supermarkets, hardware stores. Once the mouse was partially...
  14. Externet

    2 Portable generators

    Never use an UPS for printers. Only for the CPU, that is what you want to protect from outages and perhaps monitor in order to shut down properly.
  15. Externet

    Samsung TV does not like free air signals

    Aiming a TV antenna yields the most unpredictable results in the word on RF/electronics, to the point of a coat hanger under your bed being capable of producing better reception than a fancy roof antenna. Plus Samsung building cheaper tuner modules because most people connects them to higher...
  16. Externet

    Trumps solar wall, forget politics we should just build the thing

    You are dreaming. It will last less than a week under a rain of stone throwing. And they will never pay for the damages. They do not even have to pay for their ammunition to destroy it. And the solar panels would be on their south side, if you did not think about it.
  17. Externet

    Replacing light bulbs with LED's for illuminating a radio's scale

    Diagram is good. Color is your preference. Probably 'warm' white will go better with the age of receiver. There is also more efficient types that give more light with the same current. Aim the LEDs beam spaced towards the edge of glass ends. Avoid under and over aiming the glass, or place...
  18. Externet

    Replacing light bulbs with LED's for illuminating a radio's scale

    Bulbs 1,2,3 are supplied by AC. To use LEDs there, would be convenient to insert a 1N4001 diode in series to S4; and resistance values for R22,23,24 changed to 1KΩ/0.25W. Observe polarities on LEDs. You will end with insufficient illumination spread for the dial after the surgery. Try 6V...
  19. Externet

    Help finding unusual power supply

    You can use two 12V PS wall adapters, connected this way : (+12V)----------(+)PS1(-)----------common----------(+)PS2(-)--------------(-12V) Connect 'common' to both terminals marked as 'Com'. The ground should be picked from the wall outlet or properly. Is there is a label on the device to be...
  20. Externet

    Motion sensing mouse trap

    On the floor, sticky glue sheets with bacon at its center works.
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