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  1. Externet

    Direct connecting solar panel to 18650 lithium cell...

    Hi. If a 1 Watt little solar panel outputs 4.0V at full sunlight; direct feeding a lithium cell will charge it to that maximum 4.0V at a maximum capable rate of 0.25A into a discharged cell, reaching perhaps ~85% state of charge. If the solar panel is 4.5V instead; it will apply overvoltage to...
  2. Externet

    Hight input impedance DC buffer ?

    The voltage follower works well. Re=100K yields 15MΩ loading to Vin with a 150beta 2N2222A. No more overloading of the triangle wave. Output is near desired range. What would be the effect of adding some resistance to the collector ? Would it produce less or more attenuation at Vout ?
  3. Externet

    Hight input impedance DC buffer ?

    Hi. I believe am loading my circuit too much and collapses. Am I seeing it wrong ? A 7555 IC as astable has 100KΩ as 10μF capacitor charge path and 100KΩ at its discharge path for ~ 0.2 Hz I want to use the oscillation at the capacitor, that goes from ~1VDC to ~2VDC (1/3 to 2/3Vcc) triangle...
  4. Externet

    THIS is a good paint job...

  5. Externet

    Is it wrong to leave a transformer plugged in ??

    Where is the supply installed? If reachable, a switch can be installed at an aluminium end 'wing' to cut off the mains input instead of the output. Mine are under the upper kitchen cabinets with mains switch added.
  6. Externet

    Suggestions on analog galvanometer ?

    Thank you, fellows. The first plan is to bend the pointer back crossing the pivot center and glue the mirror there. It is actually glass, first surface, gold coated, flawless optical quality perhaps (corrected) only 0.5mm thin ~half a penny thin. Nearly unobtanium, got 200 pieces. Cannot weigh...
  7. Externet

    Suggestions on analog galvanometer ?

    Unless better options you may suggest; am after a as I have to glue a 15mm x 10mm x 1mm mirror to its pointer. Will be driven by a 7555 triangle wave repeatedly at 1 Hz. Scale and housing is irrelevant, unnecessary. Am after the movement only. Do you see an alternative way to make such a...
  8. Externet

    Which video adapter to use ?

    Thanks, Bob.
  9. Externet

    Old remote control repair

    First check battery and contacts being firm and scraped. Look if 9? V gets to its board. Then, check the buttons make contact when pressed. Try activating next to an AM receiver antenna, perhaps makes some noise. Measure power supply at the receiver module.
  10. Externet

    Which video adapter to use ?

    Thanks. Nope, that is for VGA; should be CGA input, composite output.
  11. Externet

    Which video adapter to use ?

    Hi. Is there a converter gadget to display this RGBIHV video output into a composite monitor input ?
  12. Externet

    Lithium ion canteen...

    Arithmetics do not fit perfect. 5.0V supply - 0.7V drop yields 4.3V for charging If the cell is 3.7V charged, minus 0.7V drop feeds 3.0V to camera. (Had to split the post in two portions as got message of being too large)
  13. Externet

    Lithium ion canteen...

    Hi. How whacko would this be to use as a simplistic external 'canteen' supply for a digital camera that uses 2xAA cells that not last much ? Currently am using the right portion only to supply the camera and has worked very well for 4 years, and I transfer the 18650 to recharge on its...
  14. Externet

    250v switch

    What side of the adapter is switching, primary or secondary ?
  15. Externet

    Microcap Boost converter

    Your homework to find the other parameters. ----> https://www.amazon.com/Voltage-Converter-Regulator-Transformer-Waterproof/dp/B077N62328?psc=1&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-d-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B077N62328 What is Microcap ?
  16. Externet

    hi fellow hobbyists.. ?about sensors

    Obtaining the linked items, you can dismantle it to individual pieces, trace its schematic, learn/study how it works and put it all together again as you will have all the correct components, quantity-one and tested to work with no ordering wait, including the hardest to find, a proper housing...
  17. Externet

    hi fellow hobbyists.. ?about sensors

    ---->...
  18. Externet

    Make an Oscilloscope?

    Kits like from post #2 can connect its output to the input of : ----> https://www.aliexpress.com/wholesale?SearchText=oscilloscope+kit&opensearch=true Which include a small LCD monitor. Perhaps there is one listed with composite output to connect even to a huge television, or VGA output to a...
  19. Externet

    Simple moisture meter circuit?

    ----> https://www.aliexpress.com/wholesale?SearchText=garden+moisture+soil+meter&opensearch=true
  20. Externet

    Make an Oscilloscope?

    To make a waveform generator you need to order all the correct parts, make a printed circuit board, or assemble this : ---->...
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