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  1. MP1

    Flashlight without batteries

    I do not have a ready made circuit for you. I would have to design it and I do not have the time to jump into another project at the moment. When I have the time available, I will put something together and upload it to the forum. MP
  2. MP1

    Labeling the project box

    OUS was meaning Outside the US. Did you find anything out from those sources? I have not had a chance to pursue it since my last post. MP
  3. MP1

    Flashlight without batteries

    glebka11: Receive the wave with an antenna into a vari-loopstick, then rectify the signal with a diode and a few filtering components. You will not get much current, but I am sure it would light a bulb or LED if you tune it well enough. MP
  4. MP1

    Absolute Newbie needing help

    Actually, if you use a "black Light" bulb, it will take less time and not generate the heat requiring a fan. The heat actually impedes the imaging process with the photo etch chemicals. My system uses 4 18" tubes and can produce a 12" x 12" board in a very short period of time. If you only need...
  5. MP1

    help

    Yes, up to the allowable value of the resistance. (V/R=I) After that you get heat and after that you get the smoke if the resistor cannot handle the power dissipation. ;D MP
  6. MP1

    A (simple) question about PSU

    Yes, these are for high frequency filtering. It is hard to find a 0.6 microfarad or 0.7 microfarad capacitor, which is what this makes up. Also, some designers like to parallel capacitors because each capacitor charges to the same voltage, without regard to the behavior of the other capacitor...
  7. MP1

    Construction of digital thermometer

    What kind of accuracy are you looking for? Thermisters are not that bad for most applications. You might also look at the LM34 and LM35 from National Semiconductor. Again, you need to list how tight the spec. And how are you calibrating it? Another question: are you using a microprocessor to...
  8. MP1

    LM317 Variable power supply

    I have built quite a few of these. There is a LM317 calculator in the "Articles" section of this site. On the page, there is a link to a tutorial with some added information. In addition, if you could post your schematic including the information written on the back of your wall wart, I am sure...
  9. MP1

    dm7407

    Yeah, I think Radio shack discontinued the 555 some time ago, too. They haven't caught on that it still exists, either. MP
  10. MP1

    LM317 Variable power supply

    You are losing a bit when you pass the DC voltage through the rectifier bridge. The rectifier bridge is for the AC input. Just tie into the circuit after the 4 diodes that make up the rectifier bridge or somewhere on the trace that goes to the input pin of the LM317. As long as you have enough...
  11. MP1

    need help

    Beerman, Eagle 4.11 has a free hobbyist version. I highly recommend it. http://www.cadsoftusa.com/freeware.htm MP
  12. MP1

    dm7407

    I am not aware that anyone has discontinued this device. Where did you get that information? You can get the Texas Instruments SN7407 for about 60 cents at digikey. I just checked their website and they had more than 500 in stock. MP
  13. MP1

    "Snap-in mount" capacitors

    I have purchased these in the past. The legs are bent to an angle which permits them to snap into the circuit board for a snug fit. I have not seen any sockets for them, but perhaps they do exist. MP
  14. MP1

    Power supply for AMP in CAR

    Ante: I do not think this debate really belongs in this thread. Others are probably tiring from it. I will have to stop now. Please check out the link above for more on transistors. In answer to the question...since all of your transistors are on at the same time, your resistances are all in...
  15. MP1

    Flashlight without batteries

    rectify the radio signal so that it is DC. Actually, I used the term "1 transistor" to mean simple, but I am not sure that you even need a transistor. MP
  16. MP1

    Car Burglar alarm

    You could store the message on a ISDxxxx record/playback chip. Instead of triggering the relay forr the horn, you could send the pulse to this chip and have it play the message. There seem to be a few of these chips with different numbers, so I replaced the number with xxxx. MP
  17. MP1

    Flashlight without batteries

    I have not really been following this thread, but why not just use a one transistor radio receiver circuit and rectify the received wave with a diode to use it as a power source. (radio waves are everywhere). You should be able to get about 3 volts from this. You then only have to connect it to...
  18. MP1

    Power supply for AMP in CAR

    Yes, I work in the consumer electronics industry. I have also seen the amazing things that the industry gets away with. ::)Consumer electronics is not based on good design. It is based on how much money the company can make. If you can leave out several 20 cent parts and sell several hundred...
  19. MP1

    Build a simple PC oscilloscope

    You are correct. Most PC devices will not allow more than 5 volts. Some cards have over voltage protection, but I would not use a higher voltage as a test to find out if yours has protection. You should decide what your highest voltage will be. Is it 5 Volts Pk-Pk?, 10 volts Pk-Pk? When you have...
  20. MP1

    Heeeeeeelp!!

    Glad we could help. I trust the wedding is still on, then? ;D Take care! MP
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