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  1. Herman the German

    Re: sensor circuit

    Hi Albert, you might substitute the photo transistor with a normal NPN transistor. Apply base voltage which will simulate the light passing to the photo transistor pulling the collector low. Switching the base to ground will then simulate an obstructed view switching the collector high. The...
  2. Herman the German

    power supply ircuit Help

    OK! Partially agreed.  :D Subtract 0.1V for a final charge voltage of 14.4V to make it safe!  ;) Beyond 14.4V any lead-acid battery starts gasing (Hoffman's electrolytic gas production facility)  ???  ??? H + O mixed make a beautiful firework if touched off by the spark of a switch.  ;D HtG
  3. Herman the German

    need some ideas for a perimeter alarm

    Hi Joulian, the problem would be an omnidirectional sensor. It must be rotating either mechanically or electronically like a radar antenna. That sensor system being carried by a person has yet to be invented. What is your personal problem? Are you afraid being alone in the dark? Do you...
  4. Herman the German

    power supply ircuit Help

    Lead-acid-batteries are charged with constant voltage e.g. 13.8V. Their charging current decreases while they approach full charging voltage. NiCads are charged with constant current.
  5. Herman the German

    muzzle flash

    Hi Simon, I don't know the reason why some of my posts were deleted. I guess it's a simple data base error, since none the posts was abusing or aggressive. I did the design using Eagle (not 123 PCB). You might download a free version (Eagle light) from http://www.cadsoft.de. Eagle light is...
  6. Herman the German

    Electronic Fish Feeder

    Hi tags, I've never built an automatic fish feeder. Fish can easily survive in an aquarium for a period of two months without being fed. If you know you're staying out of house for a longer period just feed a bit more for about one month. This allows the fish to put up extra weight which they...
  7. Herman the German

    muzzle flash

    Turn it around from uF via nF to pF to make sense! How could it possibly help if it's wrong?
  8. Herman the German

    muzzle flash

    To make a burst of three flashes you will need two timer ICs, one wired as a monostable and the second as an astable MVV. Timing must be accurate enough to have the astable put out three pulses until the monstable times out and keeps the astable in reset condition. At 80ms pulses and  50% duty...
  9. Herman the German

    variable delay trigger

    How are you going to see an LED flashing at microseconds?
  10. Herman the German

    Candle flicker led schematics?

    Hi stuee, you might try this circuit. It uses two timer ICs and a decimal counter. Function: Timer1 (IC1) generates  the clock frequency of 380Hz for the counter while timer2 (IC2) generates enable pulses for the counter. Since the frequency ratio is not dividable with an integer result the...
  11. Herman the German

    what's the difference between 1N5402, HER502, and FR502 diodes?

    Hi Sukhbinder, I guess there is no difference in general purpose rectifier diodes and high efficiency ones. The manufacturers might call a general purpose rectifier a "fast rectifier" diode or what so ever. Fast recovery diodes can normally stand multiples of the rated current being pulsed...
  12. Herman the German

    proposal:musical water fountain...kindly help..

    Please get somebody to translate your post to plain English. HtG
  13. Herman the German

    Transistor Switch???

    Hi AN920, this has nothing to do with the circuit you are discussing. After having purchased a lousy, but expensive simulation program I'm looking for a better one. Would you kindly give me the name of the one you are using? Thank you in advance. Kind regards HtG
  14. Herman the German

    Energy saving device - can they work?

    Hi again today Ldanielrosa, I know about this stuff. They sell it in Thailand for a relatively high amount of money (about 32US$). My friend purchased such a thing and he gave me permission to open it. The box was glued together all over for good reasons. Inside there where three capacitors of...
  15. Herman the German

    HELP!!!I NEED YOU ALL

    Hi Ldanielrosa, he doesn't have anything to type low case letters because he is using a Radio Shack TRS80 (Trash80)  :P
  16. Herman the German

    Printing negatives from Eagle.

    Hi, I had the same problem. For differential etching the film must be inverted. I made a normal positive print and used reversing film to make a negative. There is reversing film at the market and it can be exposed like a board with photoresist. That way there were only negligible inaccuracies...
  17. Herman the German

    500W sine wave inverter design

    Who told you the SEAT IBIZA 1.3 is a car?
  18. Herman the German

    So how do i create a PCB from schematics in eagle please

    Making a PCB with EAGLE is just as fast as an eye twinkle. Type "board;". Don't forget the colon. Eagle will ask you a silly question: "The board does not exist. Create from schematic?" Click OK and you'll have a board instantaneously. All components are placed beside a standard board of...
  19. Herman the German

    Are datasheets important?

    P.S. I purchased a 3000VA inverter in China to be deliverd next month. I'll take it apart and look how that one works. I am well acquainted to the sales manager and she will also deliver a schematic of that device if I join her wedding party.
  20. Herman the German

    Are datasheets important?

    Hi audioguru, well, a CD4047 will do the required job. I just thought of the 100Hz cycle it produces internally to be divided by two. It is kind of hard to achieve a stable 50Hz cycle anyway. Higher frequencies are easier and using the appropriate output and just one transistor for inverter...
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