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  1. Externet

    Markings on analog moving coil meters...

    That's it ! Thanks.
  2. Externet

    Markings on analog moving coil meters...

    Hi. V. A, VU meters usually have markings on the bottom of the scale. I suppose tell full scale current, internal resistance... Were to look for the meaning ? Is there a standard for markings ? Several types:
  3. Externet

    Green 532nm DPSS laser pointer...

    Thanks, fellows. Those cheap laser pointers publish no specifications of their built-in drivers, or if they could accept 4.2V from a lithium cell; and I need to use their factory drivers to keep at the mandated allowed 5mW optical output. A constant 3V supply as the 2xAAAs they are meant to work...
  4. Externet

    Once a minute chirp...

    Correct, Hevans. I goofed about my link; that one needs the oscillator to be fed. The intention was a 1 minute relaxation-neon oscillator? to provide signal for your correct type of linked chime/buzzer avoiding transformer power supply towards simplicity and bulkiness. Will try your suggestion...
  5. Externet

    Green 532nm DPSS laser pointer...

    Hi. Looking to make a 5mW(optical) at 532nm generic cheap laser pointer module that operates on 3V (2xAAA cells) work from 4.2V fully charged to 2.5V full discharged 18650 cell. The Vf for 808nm is supposed to be 1.9V. Such pointer is supposed to have a current regulator IC built in. Would it...
  6. Externet

    Once a minute chirp...

    Hi. Trying to make an about once-a-minute chirp/beep/chime, capacitive? resistive? coupling from 120VAC. Capacitor, rectification, slowly rising DC trough a very large resistance until the rising level discharges a short (0.5 second?) burst to a piezo buzzer emitter kind of circuit. Then, start...
  7. Externet

    Obbey the president...

    Spectacular ---->
  8. Externet

    Movement sensor

    Yesterday saw this gadget at Goodwill for $1. Thought of this thread... This counts money, not coins. I suppose by the amount of opening the coin pushes at the insertion slot width assigns a value. Hackable to just count number of coins, (if that is the intention) I suppose. Hevans : On...
  9. Externet

    Movement sensor

    Not that matters much for detection; but with such emphasis in 'horizontal slot' , clarify : if the slot is horizontal on a vertical panel (slide-in/push-in) or the slot is horizontal on a horizontal panel (drop-in) Seen from above ( - ) or ( | ) The picture that did not post at #3 before ...
  10. Externet

    Movement sensor

    Or, Abundant and canibalizable from a defunct printer : Optointerrupter, optocoupler, slot opto sensor and other names. -Don't know why image does not show...:( Perhaps this helps ---->...
  11. Externet

    Powering device with Cat5e data cable

    For a momentary drain use any. 1 or 2. For a permanent drain, use 2 or 3, if you no not want the extra spare pair for something extra/future.
  12. Externet

    Frequency generator

    ----> https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20190106121319&SearchText=function+generator+kit Or look for ICL 8038 data sheet/application notes. For sure there is newer chips too. One of them ---->...
  13. Externet

    Powering device with Cat5e data cable

    Should be at least 0.5A per conductor, and can be paralleled. What is the needed current ? What length ?
  14. Externet

    Direct connecting solar panel to 18650 lithium cell...

    Found it. It is a circuit I made when chargers were not available, not even cells were on the market, and charging voltage was "never more than 4.1V", cells were only available salvaging from defunct equipment - 1N5335B 3.9V 5W Connected a zener to a cell with 3.95V ; drained 95mA...
  15. Externet

    Direct connecting solar panel to 18650 lithium cell...

    Am not sure if remember details that long ago. It may had been just while charging wired to the cell holder, then cell removed. Will find those zeners and measure current when paralleled to a cell not being charged. About the 3.6V figure, there is something that bothers me, unrelated to the...
  16. Externet

    Direct connecting solar panel to 18650 lithium cell...

    Once I tried (empirically because I had them) 3.9V/1W zeners in parallel to lithium cells and behaved decently, not allowing to rise over 4.1V
  17. Externet

    Direct connecting solar panel to 18650 lithium cell...

    Thanks, *steve*. What is worse to select; a 4.2Vz zener or two series 2.1Vf green LEDs in parallel to the lithium cell, for a high resistance charging voltage ? 6V source(+)-----------------1KΩ-------------(+)18650(-)--------------------(-)
  18. Externet

    Looking for older LED's

    It is red. Designed in '92 to illuminate a track on cinema film projectors to decode digital audio. Unobtanium made by Opto-diode, 1.2Vf. My camera will not produce a meaningful close-up, arrays in it are about 0.1mm wide x 3mm long. I could send it to your mail box.
  19. Externet

    Looking for older LED's

    Hi. I have a bunch or weirdo LEDs, gold plated, with two linear micro arrays of like 10 emiters each; look similar to But not that old. Perhaps the nineties. Are you after pictures or the diodes ? Its manufacturer does not publish pictures; these are very custom.
  20. Externet

    Direct connecting solar panel to 18650 lithium cell...

    About the diode, I disagree. A dark solar cell behaves as a diode. A dark solar panel behaves as a series of diodes. For a diode to conduct, the voltage applied to it has to be over its Vf. (A)---------------|>|--------------(K) Vf=0.7 For a series of diodes (panel) to conduct...
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