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  1. audioguru2

    Another INVERTER we can talk about..

    Hi Sasi, Where is your schematic? I agree that MOSFETs are better, but are not available everywhere like 2N3055 transistors are. Those MOSFETs cost the same as 2N3055s in Canada, and they are both very cheap. Hi Rhonne, To switch the frequency of the 4047, use a 47K resistor for 100/50Hz, and...
  2. audioguru2

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

    Hi Bohda, In this one and in the other forum we discussed and recommended the changes that you are talking about. I am glad that you agree with us. However, we need a supply of 0V to 30V, not 0V to 15V and 15V to 30V, so we will not switch the transformer's windings. Thanks for posting that...
  3. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, I don't care about my old hat. What about the new windows in my home? And my hearing? And my wife? And my dog? ;D The cars in the SPL contest have Lexan instead of glass, since at nearly 150dB the actual air pressure is almost +,- 15lbs/square inch. Of course, nobody is inside the...
  4. audioguru2

    Electronic parasite zappers

    Hi Steven, Is it an electronic doctor, or just another Viagra ad? How many volts did you arc to your skin? You must be numb to sparks by now. I don't like to touch only 24V.
  5. audioguru2

    Another INVERTER we can talk about..

    Hi Rhonn, Oh goody, another one! I figure that it will give about 200W. A few comments: 1) Those nice 2N3772s cost nearly 3 times as much as ordinary 2N3055s. If you parallel two 2N3055s on each side, the performance will be the same but cost less. 2) The BD239s will be running at their limit of...
  6. audioguru2

    Is It Possible To Make the DVM Portable?

    My LCD meter runs for years on a little 9V battery. It even shuts iself off when unattended. Newer ones have a backlighting button that probably also has a timer.
  7. audioguru2

    Levitating Globe

    Hi Hotwaterwizard, Thanks for your links to sites of DIY hanging thingys. Hall effect sensor for distance feedback to the coil driver! I didn't think of that. Did you see the beautiful one that sells for only $1600US?
  8. audioguru2

    Latch does not work with transistor loaded

    Hi Sid, I hope that you aren't mixing regular CMOS with TTL logic ICs, because they are not compatable without making changes. The "high" output voltage (2.4V minimum) from a TTL IC will not always be high enough to be recognised as a "high" input voltage (3.5V minimum) at the input of a CMOS...
  9. audioguru2

    Problem w/ j/k flip flops?

    Xerxes, Good, you did a fine job.
  10. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, Yeah, It seems to be best to use your new woofer in a big, ported enclosure with a bit of EQ. Your posts of high-quality woofers reminded me that I have a very high-quality, very high-power, very long-excursion, very.... etc. 18 inch woofer still in its packing case. It weighs a...
  11. audioguru2

    Latch does not work with transistor loaded

    Hi Vajirkar, So this is the rest of your "sparking relays" circuit. I see the same problem as GPG did: The inverters (which I hope are CMOS, not TTL) that are connected to the limit switches have a very high-value resistor of 1M on their inputs, and also unshielded "antennas" from the limit...
  12. audioguru2

    Is It Possible To Make the DVM Portable?

    Going another step further, you can also save display current if you add a circuit to flash the display briefly, and keep it blinking for a while. If the "on" time is 20mS, and the "off" time is 480mS, the display will brightly flash twice per second and use an average of only 1/20th of the...
  13. audioguru2

    scalar beamer

    Hi Steven, I use a digital CMOS IC for my noise generator, but it is now obsolete. A good noise source can be made by causing the reverse-biased base-emitter junction of a silicon transistor to avalanch (at about 7V), like as done here: http://www.web-ee.com/Schematics/Pink%20Noise/pink.htm
  14. audioguru2

    Problem w/ j/k flip flops?

    Hi GPG, Sure, a 7404 TTL IC can sink 16mA through an LED, but does its output voltage go high enough to turn it off? If not, then why not just add a diode or two in series with the current-limiting resistor? The outputs of the 74154 can also sink 16mA, so why aren't the LEDs connected to it...
  15. audioguru2

    fast switch-off for transistor switch

    Hi Trigger, Of course your triac will eliminate the spark, because it eliminates the relay contacts. And the diac-triacs must be optically-isolated, so that the entire circuit isn't "live". Four diac-triacs will need to be connected in an H bridge, to reverse the motor. But I think that a triac...
  16. audioguru2

    neon bulb flashing ..............

    Many years ago I potted flashing neon lights together with two 45V batteries in clear plastic. The plastic was completely solid with the parts inside, like they do with coins. It was a flashing chaser that looked really neat. A couple of months later, it blew-up, because I didn't allow a vent...
  17. audioguru2

    fast switch-off for transistor switch

    Hi Sid, That's it! I think that it is normal for a relay contact to spark if the inductive motor is disconnected from the mains supply at the moment that the AC voltage is at its peak of 170V. The resulting hundreds of volts of back-EMF will also cause arcing at the bouncing contact of the...
  18. audioguru2

    Problem w/ j/k flip flops?

    Hi Xerxes, I'm glad that you got you counter working. Now you must make a 5V power supply for it. Your 7400-series ICs use too much current for a zener diode and for a 9V battery. For a suitable 5V power supply, see: How Stuff Works, How Electronic Gates Work, The Power Supply. A 7404 is a...
  19. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, I'm disappointed by your estimated response curve for the new Focus woofer. Since the Qts is almost perfect, I expected its response to be very flat down to about 40Hz. Maybe its resonance frequency is too high for a sub. Are you ready to make awesome bass? You've probably seen it...
  20. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, How are you able to lift that thing? Also, its rubber surround is huge so it must have a long excusion. Let's see your sim of it.
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