Tube Amp

Started by Dave.H in sci.electronics.basics12 years ago 13 replies

Hi, I'm looking for plans for a 1 or 2 tube low voltage amplifier to go with a regenerative radio. Does not have to be the best, but needs to...

Hi, I'm looking for plans for a 1 or 2 tube low voltage amplifier to go with a regenerative radio. Does not have to be the best, but needs to drive at least 250 mW speaker, preferably 1 watt or more. Thanks, Dave Australia


Dialer problem with a picchip

Started by lerameur in sci.electronics.basics11 years ago 31 replies

Hello, I have a recuring problem when connecting my circuit to the phone line. basically the circuit I use is...

Hello, I have a recuring problem when connecting my circuit to the phone line. basically the circuit I use is : http://ourworld.compuserve.com/homepages/Bill_Bowden/autocall.htm with the exception that I connect B3 to an 8th order low pass filter and the output of that goes to the positive of the transformer. Also I use picbasic to create my DTMF. I connected a small audio speaker to th...


Networking Router near a speaker(magnet) ??

Started by Robert Blass in sci.electronics.basics11 years ago 4 replies

I've asked this question in the networking/router newsgroups and those guys give conflicting answers so I wanted to ask you guys since...

I've asked this question in the networking/router newsgroups and those guys give conflicting answers so I wanted to ask you guys since you'd probably know better. Almost everyone in the etworking/router newsgroups say the problem I have has nothing to do with my router being near my speakers. My router is on top of one of my stereo speakers. It's a 50 watt speaker and is not being used A...


will a dc offset affect a speaker?

Started by panfilero in sci.electronics.basics11 years ago 44 replies

ok... here's my question: If I have a millivolt range audio signal and I add a dc offset to it, and then I take my new signal and send it to a...

ok... here's my question: If I have a millivolt range audio signal and I add a dc offset to it, and then I take my new signal and send it to a speaker with a built in amplifer, will this be the same as sending the audio signal alone to the amplifier? What I think: I think yes... because the way speakers work is by vibrating along with the fluctuations of the audio signal, and since a dc s...


How to test speaker ohms?

Started by muzician21 in sci.electronics.basics11 years ago 43 replies

I want to replace the midrange of a Fisher speaker model ST-440 "Studio Standard Series". No idea what vintage it is - maybe 80's...

I want to replace the midrange of a Fisher speaker model ST-440 "Studio Standard Series". No idea what vintage it is - maybe 80's or 90's. What's on the back is SB-80521-1 L81TNK AFAIK it's a factory speaker. Obviously I want to replace it with the right kind of speaker. I have a multimeter, how do I test it? Only one is damaged - it's been torn since I got them at a pawn shop - bu...


Building a class A audio amplifier - no audio out

Started by Anonymous in sci.electronics.basics11 years ago 68 replies

I tried to build this Class A amplifier circuit as a learning experience: http://www.techlib.com/electronics/audioamps.html#class-a with the...

I tried to build this Class A amplifier circuit as a learning experience: http://www.techlib.com/electronics/audioamps.html#class-a with the following modifications: 1. I have no MPSW45, so I built a Darlington out of a 2N2222 and TIP31A. 2. 150k resistors: I only had two 100k resistors in my collection. But as long as they're identical, should work...??? 3. speaker: I had only a 10W...


need a quick ultrasonic noisemaker

Started by Michael in sci.electronics.basics10 years ago 13 replies

For the neighbor's dog. Heard about the ultrasonic noisemakers that are triggered by a dog's bark, but at $50 and several unfavorable comments,...

For the neighbor's dog. Heard about the ultrasonic noisemakers that are triggered by a dog's bark, but at $50 and several unfavorable comments, thought I'd try to roll my own. Aiming for 16-20 kHz. In a bit of a hurry at the moment, so no C, R1 and R2 chosen yet, but is this a good idea? I've got a couple spare 12V lead acid batteries lying about, and a couple of spare 4 ohm car speaker...


Diodes for 12v battery charging

Started by Stumpy in sci.electronics.basics10 years ago 22 replies

I put in a 12v solar panel to charge up 2 ATV's and a mini tractor. Ran some speaker wire and battery clips to charge all of them in parallel. ...

I put in a 12v solar panel to charge up 2 ATV's and a mini tractor. Ran some speaker wire and battery clips to charge all of them in parallel. The tractor battery seems to not hold a charge very well. I'd like to add 3 diodes to protect the other 2 batteries in case at night with no input current, the low battery would siphon off power. The setup is in a very remote location with no ...


Magnet Damage to LCD

Started by Affan in sci.electronics.basics10 years ago 8 replies

So, I know that speaker and light magnets donot damage LCD like they used to dmage CRT's. However, my daughter a mere 2.5yrs old, took a magnet...

So, I know that speaker and light magnets donot damage LCD like they used to dmage CRT's. However, my daughter a mere 2.5yrs old, took a magnet and was able to make entire area on the screen go completely black. First question... anyway to repair it? second, how could this happen?


building a small amplifier for the first time

Started by Michael in sci.electronics.basics9 years ago 9 replies

I finally settled on this one: http://www.techlib.com/electronics/audioamps.html#computer Questions: 1. Would a 2N2222 work instead of the...

I finally settled on this one: http://www.techlib.com/electronics/audioamps.html#computer Questions: 1. Would a 2N2222 work instead of the 2N4401? I've got a bunch of quad-2s in my bin. 2. Would it be ok to substitute 1-ohm resistors for the 2.2 ohm resistors on the speaker side, if I use a larger speaker? I've got a spare 4-ohm, 10W speaker from when I upgraded the car's audio syst...


Speaker/ Amp impdeance

Started by George Herold in sci.electronics.basics9 years ago 38 replies

There was a question about speaker impedances (8 Ohms vs. 4 Ohms.). On a list server that I follow. Several reponders mumbled about matching of...

There was a question about speaker impedances (8 Ohms vs. 4 Ohms.). On a list server that I follow. Several reponders mumbled about matching of the speaker impedance to the amplifier impedance. To me this sounded like a lot of hooey. I assume modern audio amps have very low output impedance. And that the 4 or 8 ohms is more about the maximum voltage and current that the amp can produce. ...


DIY amplifier+loudspeaker

Started by Man-wai Chang in sci.electronics.basics9 years ago 10 replies

I only need a very very basic speaker, powered maybe by AA batteries, that amplifies the 3.5mm audio output from the iPod Touch. Is this...

I only need a very very basic speaker, powered maybe by AA batteries, that amplifies the 3.5mm audio output from the iPod Touch. Is this going to be cheap? Could I just connect a small buzzer to it? -- @~@ You have the right to remain silence. / v \ Simplicity is Beauty! May the Force and farces be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.39.1 ^ ^ 16:33:01 up ...


class B (or is it AB?) design mods

Started by Recovering Madman in sci.electronics.basics8 years ago 3 replies

Found a circuit: http://openbookproject.net//electricCircuits/Exper/EXP_6.html#xtocid158349 What parts would have to change if I were to use...

Found a circuit: http://openbookproject.net//electricCircuits/Exper/EXP_6.html#xtocid158349 What parts would have to change if I were to use +/- 6VDC instead of +/- 12VDC, and use a 4 ohm speaker instead of an 8 ohm one? Would it still work if I use +/- 3VDC?


LM386 power amp IC question

Started by Kaz Kylheku in sci.electronics.basics8 years ago 20 replies

I found an old LM386 chip in one of my piles of junk, and I'm thinking of putting it into use. All the schematics in the data sheet use an...

I found an old LM386 chip in one of my piles of junk, and I'm thinking of putting it into use. All the schematics in the data sheet use an idiotic, large output coupling capacitor between the chip and the speaker, which just makes me cringe. I'm thinking that since the IC references the output at halfway between its power rails, and since I'm using a virtual reference in the rest of my ...


Convert stereo to mono

Started by amdx in sci.electronics.basics8 years ago 14 replies

I have a new internet radio that has a a stereo headphone jack. I want to drive a single speaker with both channels. Will I cause harm to the...

I have a new internet radio that has a a stereo headphone jack. I want to drive a single speaker with both channels. Will I cause harm to the amplifiers if I just tie the outputs together and use the that to drive the speaker? OR Do I need to add some resistors to isolate the amps from each other before the speaker? Thanks, Mikek Hmm. I'm thinking headphone jacks often...


Noisy Phone (speaker?)

Started by W. eWatson in sci.electronics.basics8 years ago 6 replies

We have a Panasonic cordless set of phones. In the last month, we've noted that occasionally the ringer (speaker, I suppose) sounds very...

We have a Panasonic cordless set of phones. In the last month, we've noted that occasionally the ringer (speaker, I suppose) sounds very rough. My wife finally put it on another circuit for nearly a month. No problems. I think it's another device on the circuit that causes the problem. Here's what's on that circuit. The kitchen circuit containing the phone plug includes: 1. Kitchen...


AC current relay

Started by Anonymous in sci.electronics.basics8 years ago 15 replies

I want to switch on some receptacles when another one is drawing current. I want my remote controlled TV to turn on the equipment ancillary...

I want to switch on some receptacles when another one is drawing current. I want my remote controlled TV to turn on the equipment ancillary to the television - converter box, antenna rotor, speaker amp. Ideally something that can sense down to 1 amp or so then energize the other outlets, and uses minimal current itself. These things used to be fairly common to switch off the other comp...


Tide table audiograph

Started by Stumpy in sci.electronics.basics8 years ago 14 replies

I was looking at a tide table to find minus tides during the daytime to go poke at creatures and I thought that the fairly regular wavelength...

I was looking at a tide table to find minus tides during the daytime to go poke at creatures and I thought that the fairly regular wavelength would make some very boring music. If you sped up the frequency from days to kHz and had feet represent either volts delivered to a speaker, or actual sound waves you would hear something. Probably a very regular tone that varied more in volume t...


Electrolytic capacitors & playing with 556 chip

Started by Adam Funk in sci.electronics.basics8 years ago 14 replies

I wired up a 556 (two 555 timers on one chip) as follows: Timer A: astable circuit with equal mark & space width, R = 267 ?, C = 1000 µF...

I wired up a 556 (two 555 timers on one chip) as follows: Timer A: astable circuit with equal mark & space width, R = 267 ?, C = 1000 µF (electrolytic with 25 V rating), output: 320 ? in series with an LED, also tied to the reset pin on Timer B Timer B: same astable timing arrangement, R = 100 k ?, C = 10 nF (non-electrolytic), output: piezo speaker in series with a resistor


Designing The Perfect Coil?

Started by Ron Hubbard in sci.electronics.basics8 years ago 113 replies

I want to do an experiment in brainwave entrainment by making a 7 Hz sine wave oscillator out of an XR2206 frequency generator IC and a LM386...

I want to do an experiment in brainwave entrainment by making a 7 Hz sine wave oscillator out of an XR2206 frequency generator IC and a LM386 amplifier feeding a six inch diameter coil-- which should probably fit around my fat head. ;-) The LM386 has an 8 ohm output, so it shouldn't be hard to find a speaker, if I wanted to use one; but I don't know how to make a good 8 ohm coil to radia...