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  1. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, Yes, the TL072 has the same pinout as the TL062. Don't worry about vibration, except don't use an IC socket. That's a nice amp, but as the author says,"... and it might be necessary to connect a low value (47pF ?) capacitor between collector and base of Q2" and "In reality, it is...
  2. audioguru2

    Connecting An Audio Output to 20 Headphones...

    Yeah and Yea, MP, Congratulations for posting more than 1000 entries. Now you win an LED (not Luxion) of your choice of colour! Right, Mixos? That's the end of car stuff.
  3. audioguru2

    Connecting An Audio Output to 20 Headphones...

    Ante, I KNEW that you would have a Saab, that's why I mentioned it! ;D I think that the starter motor's solenoid draws a lot more than 1A to cause the ignition switch to catch fire. ??? Remember 8-track tape players? Their little solenoid sucked more than 5A, didn't they? Guys complained that...
  4. audioguru2

    Connecting An Audio Output to 20 Headphones...

    Smoke? Many years ago I used the starter motor to propel my car to the nearest gas station. A fair distance. No smoke, no problem. The relay at the starter motor conducted the high current very well. The ignition switch and its wiring were catching fire on those GM cars. Mine had a heavy duty...
  5. audioguru2

    ELM - Pocket Size MP3 Player

    Ante, Seagram's? Never in the early morning when I do my wiring. Many new ICs are surface-mount only, in new smaller packages. How do you hand-wire ICs in "bump" packages? They have little connection bumps all over the bottom, not just around the outside. I guess that you could connect to them...
  6. audioguru2

    7805 overheat and Clock signal

    Click the "Attach" button during your reply, and select the circuit from your hard drive. Only certain extensions are allowed (jpg, gif etc., it shows what) and the size limit is 3M. If it says,"That name is already used", then re-name your file and attach it again. ;D
  7. audioguru2

    Mystery object!

    Yes that's right, MP. I forgot about that. Also, some jumpers have a raised kink in them so that they can be cut to disable functions, instead of using an expensive switch. OOps, you cut the wrong one. I hate having to solder them back together in the field.
  8. audioguru2

    Connecting An Audio Output to 20 Headphones...

    I always honour datasheet spec's and ratings so that my designs are reliable. I guess that Yamaha didn't know about gold contacts on my intermittent stereo receiver. I must clean off the silver corrosion by clicking the selector switch back and forth a few times. And GM ignored the current...
  9. audioguru2

    ELM - Pocket Size MP3 Player

    Yeah, I'm not going to wire an entire circuit like that, just little SMT to DIP adapter boards. Before surface-mount was invented, National Semi. sold LM3914 and LM3915 modules, with a black "blob" for the tiny IC and very small LEDs welded on the surface with tiny wires. The LEDs were covered...
  10. audioguru2

    Audio Signal Switch

    MP, A mechanical switch doesn't have a control voltage swing to couple into the audio path, but a relay does and therefore needs careful PCB layout like these electronic switches. A dynamic microphone is low impedance and the switch's load must also be low impedance for low noise when the mic...
  11. audioguru2

    Guitar Amplifier

    Blacksheep, The article tells what to remove under "Bass Guitar, Electric Piano". That darned emitter-follower is the transistor. It is thrown out too. When the diodes and transistor are removed (plus changing a few things), then your distortion will vanish.
  12. audioguru2

    Guitar Amplifier

    Hi Blacksheep, Did you remove the "distortion-diodes" and emitter-follower from the preamp's output, as recommended in the article?
  13. audioguru2

    A VERY usefull circuit , but how...

    Hi Nano, A mixing console has many outputs (one for each microphone), each having its own volume control and a lot of gain. It would be easy to turn down the "master" output control to get the desired output level, but have some input controls turned up too high and clipping. Your home system...
  14. audioguru2

    7805 overheat and Clock signal

    Harsh, The transistor provides the clock signal at the mains frequency. Chrono, The transistor will work a lot better if you add a 4.7K resistor from its collector to +5V. What does the clock signal connect to, that is off the page? If you filter the AC from the power transformer, feed it to a...
  15. audioguru2

    Guitar Amplifier

    Blacksheep, Did you have your speaker connected directly to the output of the preamp? Sorry, but I had to ask since it would cause your problems. If the preamp connected to a power amp, does the power amp have a low input impedance? (I hate emitter-followers!)
  16. audioguru2

    Lowpass for subwoofer -project

    Hi Vainajala, Nice project, but use a TL072 dual opamp. The TL062 has low gain and high distortion. 1) That's right. Halving the value of R1 for a single input will keep the gain the same as for 2 inputs. 2) If you have 10mA in each 12V zener diode then they will each dissipate only 120mW. Use...
  17. audioguru2

    Mystery object!

    Hi Quantum, It is a "J" for Jumper. It avoids the expense of having a double-sided PCB. I have seen them that look exactly like resistors, with a single black ring that means "0" or "zero" ohms. A little one probably has a huge power rating.
  18. audioguru2

    ELM - Pocket Size MP3 Player

    Thanks Ante, I'll get some of that tiny, urethane-coated wire, and try it out. And I'll do the soldering before drinking coffee.
  19. audioguru2

    Audio Signal Switch

    GPG, You are talking about charge injection between external pins of the IC. I agree that the control voltage can be slowed down to reduce that, as well as proper PCB layout. I was talking about charge injection occuring internal, from the output of the IC's controlling high-gain inverting and...
  20. audioguru2

    A VERY usefull circuit , but how...

    Hi Nano, I agree that clipping indicators are important on power amplifiers. Detecting when the output of a power amplifier clips is complex, due to the amplifier's power supply voltage constantly changing with power output and mains voltage variations. GPG's LM3915 post will not work if...
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