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  1. bogdan2

    Simple PC thermometer

    i don't really know what the problem is. but the error should not occur in winME or 98. it is an XP problem. i does not allow direct usage of the port.
  2. bogdan2

    LM317 Variable power supply

    just a suggestion. if you cannot find a 2 x 12v transfoermer, you could use a power suply made from 2 LM317 regs in series. though, the maximum output voltage is a bit lower. i think that having that switch is the best way. also, if you could use a 3A or 5A bridge, then you will have less power...
  3. bogdan2

    Electronic Stethoscope

    CDAK, why don't you try to reduce the gain for the LM387? LM386 is a power amp, not really good to replace all the 741 amps with 386, maybe just the last one, to get a stronger output. t_ang4, what are you powering the circuit from? maybe you have suply noise? also, maybe you hgave a problem...
  4. bogdan2

    Capacitane switch

    i have a suggestion. putting the plates closer togther increases the capcity, wich is small when using water as dielectric. also, i suggest that when insulating the plates, use something wich has a high relative permitivity. this means that you will have a big difference between the 2...
  5. bogdan2

    Capacitane switch

    here is something nice........... http://www.newscientist.com/news/news.jsp?id=ns99992123
  6. bogdan2

    Capacitane switch

    why not use ultrasonics? put a senstor at the top of the tank and it can determine the distance between the sensor and the water. or, i am thinking of another way, with the capaciatance switch. maybe a better rensor would be to run 2 insulated paralel, horizonatal wires in the tank. put them...
  7. bogdan2

    cunonstant current load

    well, i know i can do it that way, but what i want is a circuit that will not need external power. just from the cap.
  8. bogdan2

    led lighting

    just a little modification. for 9V you can put 3 leds in series. so you could use 9 leds or have a series of 2 leds and 2 series of 3 leds.
  9. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    what do you mean my SOA??? well....i forgot about the ic's. maybe they can be replaced by something else? soooooo.... in conclusion the idea is to put 2 transistors in paralel....right? and change the bridge.... yes, you are right, there is a small difference in price between a 10A and a 35A...
  10. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    yes, i think that a 10 or 15A rectifer could be used.... why not use a bridge from schotty diodes? expensive, but more performant. a good transformer would be a toroidal one, probably a 30V, 200W would be suitable. i think that having 30V a.c. output rather than 24V. if we use 2 transistors in...
  11. bogdan2

    Capacitane switch

    here is a tip.... the probes don't corrode is you apply an alternative current on them. the reason why they corrode is because if electricity flows in just one way, then a process of electrolises starts. water gets split in O2 and H2 and these react, especially the O2 with the probes. also, i...
  12. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    yes, lamps are not more reliable. i think that the best option here is to either put tu 2n3055 transistors, but it think that tha will require having a 30V a.c. transformer to obtain 30V at the output, or to use a highter power transistor. or, maybe what about using 2 2n3055 transistors in...
  13. bogdan2

    cunonstant current load

    not quite like that. you see, considering the capacitor charged, it has a stored amount of electricity Q=C*U. and an energy of E=C^2*U/2 . now, Q=I*t, where t is time and I is the current trough the cap. if you discharge the cap trough a resisotor than I=U/R but U changes because the cap...
  14. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    nope, you did not understand me right. :P i was suggestiong to use the heatsink and the transistor that are already there and another resistor in series with the transistor, wich will be short-circuited(the resistor) when the voltage required at the output of the power suply is highter. what i...
  15. bogdan2

    Making PCBs with magazine's paper

    hello! i am using this method too.... only...a bit different, i don't have a laser printer, so i have to photocopy the board. but i tried with laser printers and it works fine. i photocopy the circuit printed from a jet printer on some sperial paper, similar to the one from magazines, acutally...
  16. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    well, yes, the realy and resistor and control circuit(a low power transistor, a zenner and some resistors) can be more expensive than the transistor itrself. but what about adding the heatsik? you will not need a heatsink for the resistors. yet, i think that the power resistors can be more...
  17. bogdan2

    Hameg HM205 Oscilloscope Manual

    there is a strange thing. even though the HM205 is a good and quite performant osciloscope, i can't find any info on it. why don't you try emailing the manufacturer. maybe they have the manual and can email it for you.
  18. bogdan2

    Wireless remote power supply

    i saw something on tv once. it was an implantable device. as power it used a coil wich was generating power from a magnetic field wich ws generated by the chip readrer. a cap was used for filtering. as suggested, RF is used too.
  19. bogdan2

    varible voltage, current limiting, power supply

    well, instead of using the LCD and PIC for dispaying the voltage and current, don't you think you could use a voltmeter and ampermeter kit wich display on 7-segments leds? also, another suggestion. for the negative you could use a LM317 regulator, as it can provide 1.5 amps. i am not sure how it...
  20. bogdan2

    Convert 0-30V 3A PSU to 5A or more

    ok. i have a suggestion. what if the 2N3055 transistor could be replaced by 2? this will lower the dissipation ok each transformer. but the drop on the transistors means that the output will not be as high as 30V.... or, another suggestion. put a resistor in series with the transistor. and a...
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