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  1. audioguru2

    AM to FM convertor

    Hi GG, I'm near Toronto. I was raised in Vancouver and nearly drowned in its "liquid sunshine" but never drove the trip through the mountains. I left Vancouver a long time ago when Toronto's hippies went there. I think the AM to FM converter will just play many AM stations together, power line...
  2. audioguru2

    Need help for a heartbeat detector!

    Hi Trigger, I guess the blood flows in a finger in pulses with each heartbeat. The blood either blocks or passes the red light from the LED with each heartbeat. Whoa! 2000 posts!
  3. audioguru2

    Need help for a heartbeat detector!

    Hi Bird, The output type of an LM358 opamp is a complementary push-pull emitter-follower stage like most other opamps. See its schematic attached. The LM358 and its big sister, the LM324 quad opamp, is unique in that it can operate with a single supply voltage as low as 3V, and has a very low...
  4. audioguru2

    square to sine convertor

    Thanks GG, I forgot about that appl note. Here's a modern one: http://www-s.ti.com/sc/psheets/sloa060/sloa060.pdf
  5. audioguru2

    AM to FM convertor

    Hi GG, I am also in Canada, eh. My FM dial is jammed full of good stations, a few I listen to wherever I go. I listen to AM only to hear where there is a traffic accident that I might be able to go around. AM sounds awful. Hi Andbor, It is too bad that your project doesn't work. I think that...
  6. audioguru2

    Digital Readout

    Hi RD, You have a good idea that is just the beginning of having computerized cutting and drilling. Just use an HP printer to carry a laser cutter wherever you want! You can use the tape and optics to drive an electronic counter with display, similar to a pedometer (walking steps counter)...
  7. audioguru2

    AM to FM convertor

    Hi Andbor, Welcome to our forum. Why would anyone want to listen to lousy-sounding AM on a good FM radio? I think this project would work fine, but I would double the number of turns on the coils and swap the values of C1 and C3 so it is more like the FM transmitter projects here and all over...
  8. audioguru2

    Electronic Eavesdropping Devices Detector

    Hi Badai, I just finished replying to your other posts about this project! Please keep all your questions in this thread. You can't use a breadboard for high frequencies because the capacitance between its tracks is 20 times or more than on a PCB, and the inductance is also much higher. Of...
  9. audioguru2

    detector prototype

    Hi Badai, Are you looking for parts to make the Eavesdropping Detector project? A telescopic antenna is the kind that you pull to make longer or push-in to make shorter, like used on toys and old wireless phones. A stiff piece of wire will replace it. Can't you find a BFR 90A transistor (you...
  10. audioguru2

    Dual o/p Voltage regulator

    Hi Alun, When I clicked on your bridged-amp attachment, Adobe asked if I wanted to download their new version 7.0, so I did. Thanks. Ahh, just a whopping 1W from that little amp? Here's a nice monster bridged-amp IC with a built-in power supply voltage doubler. Operating in class-H (it doubles...
  11. audioguru2

    Dual o/p Voltage regulator

    Kevin, Of course the zener helps regulate the output voltage. It holds the voltage at the emitter constant so the transistor can amplify the difference between it and a divided-down sample of the output at its base. In your circuit with a resistor instead of a zener, the emitter voltage followed...
  12. audioguru2

    wireless transmitter

    Hi Tas, It's obvious that the 1st complicated 4W transmitter (same as the one on our site) will flatten a battery in no time and probably put you in jail! It has a strong signal by using two RF amplifier stages, and proper LC impedance matching circuits. The 2nd circuit is a cheap little toy...
  13. audioguru2

    in search of a FM STEREO transmitter

    Hi Rs, That's correct, the surface-mount IC is tiny and has no legs. It will be difficult, but you could connect your own 21 wires to it, or solder it to an adapter pcb. You can easily make your own inductors. Why not just buy the kit from Australia or New Zealand? Don't you know anybody there...
  14. audioguru2

    square to sine convertor

    Hi Ro, A PLL has a square-wave output so you would lose any amplitude changes of a sine-wave it is locked in frequency with. A PLL is useful to recover a sine-wave that is buried in noise or has frequency jitter. A PLL output might have frequency overshoot and decaying frequency hunting with...
  15. audioguru2

    Need help for a heartbeat detector!

    Hi Fate, Look at "B" opamp, no negative feedback. At the low frequency of heartbeats, its gain must be 100,000 or more. You won't have to amplify it. Look again at "B" opamp. It is a comparator, and it even has an adjustable threshold! It probably already has "proper pulses" so just feed them to...
  16. audioguru2

    Coupling capacitors!

    No Prateek, A capacitor does draw a DC current when it is charging, and supplies a DC current when it is discharging. Don't your room lights dim when you turn on your computer or high-power stereo? That is caused by its filter capacitor drawing current when it is charging.
  17. audioguru2

    How link two simple LED circuits together?

    Hi Benn, It would be easy to connect those circuits together. Like this:
  18. audioguru2

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

    Hi Moutoulous, With 3 reasonably heatsinked 2N3055 transistors, this modified project can produce 5A output at any voltage from 0V to 30V. With a fan, about 7A if you use bigger supply parts. If you use 4 of those powerful but expensive transistors, a 13A/30V transformer, a stronger rectifier...
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Thomas, I've updated my recommended parts list for this 0-30V/3A project. R14 should remain at 1.5K with your low voltage transformer as in the original article. 0_to_30V_Mod.txt
  20. audioguru2

    Need help for a heartbeat detector!

    Hi Fate, You wanted a heartbeat detector so there it is. The detector part I posted has a dual opamp but not a microcontroller nor Pic. Now what do you want to do with it?
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