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  1. Externet

    Ignition coil...

    Hi. What to expect feeding a plain 12VDC automotive ignition coil with 12VAC ?
  2. Externet

    Television reception antennas farce...

    Hello. Is there anyone here that can show me an impedance-versus-frequency plot for any television reception antenna of any manufacturer ?
  3. Externet

    Impedances...

    Hi all. A normal, typical speaker being used as a microphone has a - low impedance output or a - high impedance output and requires a - high impedance input preamplifier, or a - low impedance input preamplifier ? And; a normal, typical earphone being used as a microphone has a - low...
  4. Externet

    Looking for data sheet - application notes...

    Hello. The BEKEN brand integrated circuit is BK7252UQN48 in a surveillance camera, would like to attempt modifying its operation mode.
  5. Externet

    Voltage regulator driving a pass transistor...

    Hello. A 3 pin regulator with a maximum input voltage of 35V and 1 Ampere capable like LM7815 can drive a power transistor to raise its current capability. Does the input maximum voltage for the regulator also raises as the pass transistor Vce specifications ? Or that input voltage increase...
  6. Externet

    Making a LED bulb to produce a faint light ?

    Hi. A very high resistor value or a very low capacitance across the wall switch contacts should produce a faint illumination, right ? Like 1.2 MOhm on 120VAC would conduct 0.1 mA. Will try and post results.:rolleyes:
  7. Externet

    Maker pro crevices ?

    Hi. I was not familiar with this forum before merged with 'Electronics point' ; I was familiar with a Make! site related to many things electronics and not. Is there any connection/relation ? Is there any non-electronics forum core about 'making' things within this 'Make' forum ? Thanks.
  8. Externet

    Blue strip on top of page...

    What is that moving blue thingy on top for ? Sometimes does never stop, sometimes cannot edit when on, sometimes runs until refreshed...
  9. Externet

    Can you discern the circuit ?

    Hi. From this image ---> https://en.wikipedia.org/wiki/Joule_thief#/media/File:Joule_thief.jpg Can you draw an schematic ? It is supposed to be supplied by 1.2 V and uses two individual 100uH ? inductors, a 1K and 2n3904.
  10. Externet

    Meaning of square symbol ?

    Hi. What does that faint square shown left of the date on any post means ?
  11. Externet

    Tweaking an analog VU panel meter ?

    Hi. In a playing attempt to make a quick dirty solar pyranometer indicator, connected a plain garden light solar cell to a VU meter canibalized from defunct equipment, to see if would indicate something reasonable. (-)Solar...
  12. Externet

    Capacitive supply...

    Good day. What is the voltage at C2 for this supply method ? If not allowed in the forum, please delete.
  13. Externet

    Change timing period to gadget ?

    Hello. My poor vision cannot reverse engineer now this $1 non-contact AC detector probe from Aliexpress. ---->...
  14. Externet

    Never seen this before... have you ?

    A sixteen inch vinyl record. :eek: Next to a standard twelve inch 'long play' for comparison : What do you know about ?
  15. Externet

    Old 'travel adapters'...

    Hi. Decades ago, I used to come across power travel adapters, for converting 230VAC foreign outlets to 115VAC as for U.S. shaver, hair dryer... They were surprisingly light, vented with slots but never dismantled any to find how they worked. What do you know about them ? Are modern ones...
  16. Externet

    Fat laser beams...

    Hi. Perhaps title should say 'Fat beam lasers'... Has anyone played with them ? From curiosity, bought a couple to evaluate. Chinese cheap DPSS; supposed to be 50mW at 1.8V / 300mA, ~14mm. Aiming for a 1 mile range beam visibility at night. Do you think that power will do it ? Blue presents...
  17. Externet

    Refrigerator compressor...

    Hi. Please confirm if the way it works is : When applying 120V to arrows, the PTC starter is cold and passes current to winding S (start) in addition to current flowing trough winding M (main or run) A few seconds later the PTC heats up and conducts much less current to winding S. Being the...
  18. Externet

    Toasted windings in 3 phase motor...

    Hi. Replaced a burned 2HP 400Hz motor and after dismantling wiring, found one phase wire at the power relay with open solder joint. Would that be the cause for the motor failure ? The overcurrent at failure moment could have also had melted the solder, right ? Any other probable reasons that...
  19. Externet

    Far-field antenna polarization...

    Hi. Read somewhere that a television receiving antenna should be horizontal polarized. Also read that many miles away, it does not matter if the signal is received with a vertical polarized antenna, will perform the same :confused: Can anyone explain how it works ? What polarization are old...
  20. Externet

    Where to find schematic of 315MHz receiver module ?

    Hi. It is exactly like this one : ----> https://robu.in/product/rf-transmitter-receiver-module-315mhz-wireless-link-kit-for-arduino/ The 8 pin IC on it is LM358. Had no luck.:(
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