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  1. audioguru2

    Transistor tester

    C'mon Steeve, Post the pcb so we can get the project corrected (its 4027 still has its clock pin grounded) and nicely completed. http://www.electronics-lab.com/projects/test/008/index.html
  2. audioguru2

    fm tranismiter

    Hi Alun, Both Ron and Harry have some nice designs. I especially like Harry's low distortion and very-low-AM varactor-diode modulator. Have you considered what happens when the transmitter is over-modulated? The simple AM-FM oscillator like mine is easily over-modulated and makes a huge...
  3. audioguru2

    AAA Battery Charger

    Hi Smart, Haven't you read about battery charging safety in Maxim's and Energizer's notes? Do you know how a battery's temperature is delayed on its outside from its temperature rise on its inside? Do you know at what temperature a battery will explode? Battery and charger manufacturers use...
  4. audioguru2

    AM to FM convertor

    Hi Andbor, The AM to FM converter circuit is extremely simple to do such a difficult task of converting an entire band of frequencies to a completely different band of frequencies without having an RF mixer stage. It must also spread-out the crammed-together AM stations. It must also convert...
  5. audioguru2

    fm tranismiter

    Hi Alun, It is a lot of trouble just for a toy transmitter, isn't it? But you have good ideas. We should also at least make its RF frequency crystal-controlled and the desired frequency selected with a frequency-synthesizer or PLL? He, he. ;D ;D
  6. audioguru2

    AM to FM convertor

    Hi Andbor, VHF doesn't work on a breadboard. The capacitance between tracks and inductance is 10 times higher than some of its most important capacitors. I made mine on Veroboard with its strips, but cut the extra lengths with a drill-bit and planned its outputs away from its inputs. Also I used...
  7. audioguru2

    Simple rev counter?

    Hi Matty, The revs are stepped-up in frequency by a factor of 60 by using a phase-locked-loop IC like a CD4046 and a divide-by-60 divider. The PLL has a voltage-controlled-oscillator that is sync'd to exactly 60 times higher than the actual revs. Then you display the frequency of the VCO.
  8. audioguru2

    How to get a CLOCK from a Crystal Oscillator

    Hi Master, A crystal oscillator is very accurate and stable. Their simple circuit is all over the web and available from crystal manufacturers. A digital frequency divider circuit is used to reduce the frequency of a "master" crystal clock oscillator. The MM5369 was an IC that used a cheap but...
  9. audioguru2

    Another INVERTER we can talk about..

    Hi Alun, You must keep the Q high on a tuned transformer for it to continue to ring at the reonant frequency and convert a square-wave to a sine-wave. Therefore a load ruins it. I was thinking of hitting the tuned circuit with a brief pulse of the proper direction at zero crossings and the...
  10. audioguru2

    L200 Reg plus LM741 Op Amp PSU

    Hi Woody, Good, you fixed it. The L200 must really like its ground.
  11. audioguru2

    detector prototype

    Hi Badai, A 2N2222 won't detect 250MHz very well. :'( Its minimum Ft rating of 250MHz only guarantees that it will have a tiny amount of gain at 100MHz, just enough gain to work as an oscillator or mixer at 100MHz. The Ft rating is the frequency at which the gain is only one, like a piece of...
  12. audioguru2

    Another INVERTER we can talk about..

    Hi Alun, Your idea might work if the transformer doesn't have a load and you operate the Mosfets in class-C so they don't load-down the tuned circuit much. If you time the class-C pulses correctly at zero crossings, you might even get mega-volts out of the thingy! You would probably need...
  13. audioguru2

    Having problems uploading pic's.

    I nearly bought that inexpensive 'scope. Let's see what my new avitar looks like and see if it loads:
  14. audioguru2

    Additional Information

    Hi Nab, Use www.google.com to find out what things are. When you enter CD4017 or LM358 you will get a list of links and a few will be manufacturers' info pages and datasheets. The ICs are available in different package sizes and different temperature ranges which are determined by the letters...
  15. audioguru2

    detector prototype

    Hi Badai, Why do you want a cutoff frequency as low as 60Hz with this very high frequency RF circuit? A circuit's cutoff frequency is defined as the frequency it begins its cutoff, where its output is down to 0.707 of its voltage at higher frequencies, nearly the same. As the project's notes...
  16. audioguru2

    Our Site Doesn't Open

    I just reset the offset on the site's clock for my profile. The new server's time is very accurate now and is Eastern Standard Time, somewhere just down the street from me. ;D ;D
  17. audioguru2

    Our Site Doesn't Open

    Oh goody, we are getting a new server! Thanks Mixos. ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
  18. audioguru2

    Our Site Doesn't Open

    Yeah Dazza, right now the problems have disappeared. I have tried many time today to get in but gave up.
  19. audioguru2

    Our Site Doesn't Open

    Lately I have had great difficulty getting into our site's home page, projects page or even replying to replies. I notice that in the last 24 hours only 15 posts have been made, so I guess I am not the only one. My browser tells me that it cannot find the server, that it found the server and is...
  20. audioguru2

    Running LEDs at PWM and current sensor Q.

    Hi Kain, My ultra-bright LEDs are blinding when operating at 25mA continuously. When I PWM them with 4KHz 100mA pulses at a 25% duty-cycle, they look the same. When I blink them with 20ms 100mA pulses with a 40ms pause between them, they are much brighter of course. Then I let them cool for...
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