| Author | Message | ||
     Anonymous |
what is the difference of an audio transformer and a centertaped regular transformer? | ||
| Simon Quellen Field (Sfield) |
By "regular" transformer, I assume you mean one that is designed to work best at 60 hertz. An audio transformer is designed to work over a range from 20 hertz to 20,000 hertz. A power transformer will have losses at higher frequencies, so the sound will be distorted. | ||
| Anonymous |
if i connect a audio transformer into a stereo or amplifier and then connect the speaker will the sound be louder or the same? how exactly do audio amplifiers work? how much wattage can a audio transformer handle before burning or getting ruined? | ||
| Simon Quellen Field (Sfield) |
A transformer is like a lever. The short end is the 8 ohm side. The long end is the 1,000 ohm side. If you have a strong person who wants to move something a long distance, he can push on the short end and make the long end move quite a distance. If you have a little kid who wants to lift an adult, he can climb up onto the long end and lift the adult sitting on the short end. The audio amplifier is designed to put a lot of current into an 8 ohm coil in a speaker. It is pushing hard on the short end of the lever, using a lot of current at low voltage. The transformer converts this high-current, low-voltage power into higher-voltage, lower-current power. We don't need a lot of current, but we want to change the voltage in the circuit by more than the small amounts that the amplifier uses. If you put too much power into the transformer, it will overheat, but before that happens you will destroy the oscillator. Don't do that. | ||
| Anonymous |
i dont think this has anything to do with anything based on your website but you are the only person i can turn to for help. i had recently bought a 8-track player and i installed in my car i installed everything correctly cause the instructions were on the back of the player. as soon as i hoocked it up i tested it out by inserting a 8-track cartridge. it played for a few seconds and then "POP"!! smoke came out from everywhere. I disconnected it and opened the player i discovered that one of the big capacitors had exploded and i want to know why did this happen and can you post any sites that could help me repair my player. | ||
| Simon Quellen Field (Sfield) |
You're right, the question has nothing to do with science toys or any other of my areas of expertise. However, a quick Google search for "8 track player" came up with many afficionados of ancient music storage devices, including 8-track heaven. Since the devices are no longer manufactured, I suspect you received a player that had an old, dried-out electrolytic capacitor. These are easy to obtain, and easy to solder back into the player to replace the damaged part. If the damage was caused by some other fault in the device, the capacitor will probably explode again, so keep your face away from the player when you turn it on the first time. Also, they are polarized capacitors -- make sure you put it in the right way. With 8-track players going for $15, it is probably best just to replace it. I assume you want it for effect in a vintage car, or you'd replace it with a CD player, or convert your old 8-track tapes to MP3s and use an MP3 player. | ||
| Anonymous |
I BUILT THE COMPUTER CONTROLLED TRANSMITTER WITH A 28.0214MHZ OSCILLATOR, BUT I DONT HAVE ANY (LW) OR ANY HIGH FREQUENCY RECEIVER. SO I WAS WONDERING IF IT IS POSSIBLE TO USE A (CB RADIO) AS A RECEIVER TO RECEIVE THE MORSE CODE. | ||
| Simon Quellen Field (Sfield) |
The reason I suggest 28.322 Mhz when using the 10 meter band is that the easiest license to get allows you to use that frequency. To use 28.0214 Mhz you need a General Class license, which requires another test, above the Novice or Technician class, which requires only one simple test. The Citizen's Band is the 11 meter band, so a CB receiver will not be able to receive 28.0214 Mhz. Besides, you are not allowed to use homemade transmitters in that band. The transmitter has to be tested and approved by the Federal Communications Commision if it transmits in the Citizen's Band frequencies. The Computer Controlled Transmitter can transmit audio tones using Amplitude Modulation, so any cheap short wave radio will be able to receive it, if it can tune to the 10 meter band. However, you will get much better range using Continuous Wave, which requires a receiver with a Beat Frequency Oscillator. These can still be found at reasonable prices. | ||
| Anonymous |
What is a CB radio's frequency if the chanels are from 1-25? and if a 88MHz oscillator is used for the transmitter can it be received in the 88MHz FM band? (JUST CURIOUS) | ||
| Simon Quellen Field (Sfield) |
CB radio is in the 11 meter band, or about 27 Mhz. Here are the actual frequencies: 26.965 Ch. 1 26.975 Ch. 2 26.985 Ch. 3 27.005 Ch. 4 27.015 Ch. 5 27.025 Ch. 6 27.035 Ch. 7 27.055 Ch. 8 27.065 Ch. 9 27.075 Ch. 10 27.085 Ch. 11 27.105 Ch. 12 27.115 Ch. 13 27.125 Ch. 14 27.135 Ch. 15 27.155 Ch. 16 27.165 Ch. 17 27.175 Ch. 18 27.185 Ch. 19 27.205 Ch. 20 27.215 Ch. 21 27.225 Ch. 22 27.255 Ch. 23 27.235 Ch. 24 27.245 Ch. 25 27.265 Ch. 26 27.275 Ch. 27 27.285 Ch. 28 27.295 Ch. 29 27.305 Ch. 30 27.315 Ch. 31 27.325 Ch. 32 27.335 Ch. 33 27.345 Ch. 34 27.355 Ch. 35 27.365 Ch. 36 27.375 Ch. 37 27.385 Ch. 38 27.395 Ch. 39 27.405 Ch. 40 Our transmitter is AM, so an FM radio would not hear much. You might hear the background static get quiet when it was transmitting. However, a quick Google search for "simple FM transmitter" will get you hundreds of simple one and two transistor circuits that will send FM to your radio. | ||
| Anonymous |
can a CB radio transmit to far places and if it can how big would an antenna have to be to transmit world wide? | ||
| Simon Quellen Field (Sfield) |
Citizen's Band radio uses a frequency that will bounce off of the ionosphere and travel around the world. This is why it is illegal to use high power, or to use large directional antennas, such as cubical quad antennas, Yagi-Uda beam antennas, rhombic antennas, and others you can find with a simple Google search. CB uses the 11 meter band. The 10 meter band is better, and you can get a license to use much higher powers and any antenna you like, just by taking a simple test. Many kids in elementary school take and pass the test, as it is easy, and there are books with all of the questions and all of the answers. You can even take free sample tests on the Internet to see if you are ready (just read the book you can buy at Radio Shack and you should be ready). Here is one place to take as many practice tests as you like. You don't have to get all the questions right in order to pass. | ||
| Anonymous |
How do oscillators work? what do they contain inside and is it possible to build your own oscillator? What changes the frequency inside the oscillator? | ||
| Simon Quellen Field (Sfield) |
You should look up "oscillator circuits" at Google, and read some of the many books on oscillators at your local library or bookstore. Even the ones at Radio Shack are pretty good. | ||
| Anonymous |
I did the am trasmitter and I used a portable cd player for the project. I worked ver well using the phono plug but then from a wile from trasmitting across the room and house I tried using the Cd player with headphones and only one of the speakers work and the other you just here a faint sound I tried different headphones and same results. Probably its because of the phone plug and usnig for long periods of time. But anyway I dont worrry much becasue I was about to throw that Cd player away but until I came across the project I decided to keep it. Great website I really enjoy it and so do friend and many people I/ve told about. Keep up the good work! | ||
| skaterfool |
can a Pain field Generator and a Sonic Nausea generator be built using inexpensive part and also how do they work? do they use really high frequencies or how do they work? | ||
| Simon Quellen Field (Sfield) |
You may be confusing my site with the one that sells plans for those devices. You can find them again by searching for those words on Google. | ||
| Anonymous |
im planning on building the am crystal receiver. I got enameled copper wire from a microwave oven fan motor. what would be the wire gauge for this type of wire?? thanks for your help,, -Jason | ||
| Simon Quellen Field (Sfield) |
A table of wire gauges can be found here: "http://www.reade.com/Conversion/wire_gauge.html". Measure the diameter of your wire with a micrometer, or count the number of close-spaced windings in an inch, and do the division. | ||
| Anonymous |
I downloaded the Morse Code program to use with the computer controlled transmitter then i installed it, When I tried opening the program it said that a a required DLL file was missing. So, I cant open the program. What should I do? | ||
| Simon Quellen Field (Sfield) |
Which program did you download? (There are several.) Also, which DLL was it complaining about? Lastly, which operating system were you running? | ||
| Anonymous |
I downloaded the MorseCode.exe (the one that controls the transmitter) MSVBVM60.DLL Windows 98 SecondEdition | ||
| Anonymous |
On a audio amplifier why does it say that a speaker lower than 6ohms or higher than 16 ohms cannot be used? Also if something with lower resistance like 2ohms is used will it burn out the amplifier? | ||
| Simon Quellen Field (Sfield) |
Most amplifiers have circuit cutoffs that prevent damage when the outputs are short-circuited. Amplifiers are designed to work with speakers of a particular impedance. Matching the impedance will get the best power conversion. An everyday example of an impedance matcher is the gearbox in a car. If you are in the wrong gear, the car will either stall, or the engine will rev too high and waste gas. Picking the right gear matches the engine's output to the load, and power is most efficiently transfered. | ||
| Anonymous |
3.3V and 3.0Amps is the same as 12 volts and how many amps or milli amps, also will the 3.3V and 3.0A work for a device that uses 12V and 8W? | ||
| Simon Quellen Field (Sfield) |
A device that needs 12 volts will not work using 3.3 volts. So, 3.3 volts and 3.0 amps is not the same as 12 volts and anything. A power supply that says it delivers 3 amps at 3.3 volts is saying that it can deliver as much as 3 amps into a circuit, but will never push those amps at a higher pressure than 3.3 volts. You can use Ohm's Law to figure out how the power supply will react in a circuit. Ohms law says the current is equal to the voltage divided by the resistance. If the resistance in the circuit is 11 ohms, then the current will be 3.3 volts divided by 11 ohms, or 0.3 amps (300 milliamps). The power supply can safely handle 10 such circuits. But if you had a circuit whose resistance was 0.11 ohms (such as an electromagnet made by winding 70 feet of 12 gauge wire into a coil), then the circuit would want to draw 30 amps, which is more than the power supply can provide. The power supply would start smoking and stop working, much like my cousin Eddie. Suppose you had a car headlight that was designed to draw 8 amps from a 12 volt car battery. The resistance is 12 volts divided by 8 amps, or 1.5 ohms. The headlight puts out 96 watts. If you connect the headlight to a 3.3 volt power supply, 2.2 amps of current will flow through it. It will produce 7.26 watts. That's not very bright, compared to 96 watts. But your power supply can handle the load, since 2.2 amps is less than the 3.0 amps it can supply. If you want to get 96 watts of light from a 3.3 volt power supply, you will need 29 amps of current. If you connected 13 headlights in parallel, the resistance would go down to 1.5 ohms divided by 13, or 0.115 ohms. At 3.3 volts, the current would be 3.3/0.115 or 28.7 amps. But your power supply would smoke and die, like cousin Eddie did. 3.3 volts at 3.0 amps can produce just under 10 watts. To produce 10 watts from a 12 volt power supply you need only 0.833 amps. A device that uses 8 watts from a 12 volt power supply (such as a courtesy lamp in a car) would draw 0.66 amps, and have a resistance of 18 ohms. To get the same amount of light from a 3.3 volt power supply, you would need to put 2.42 amps of current through the circuit, requiring that the resistance be dropped to 1.36 ohms. If you used 13 lamps in parallel, you would have a resistance of 18/13 or 1.38 ohms, and a current of 2.39 amps, and a brightness of 7.88 watts. | ||
| Anonymous |
what is a 9 pin and 25 pin serial port pinouts? | ||
| Anonymous |
I found a really old computer its a windows 3.0. It has a program called Terminal in the program manager. What can it be used for? can it be used for morsecode or something? or to use with another computer to send text messages?. Also im having a little bit of trouble with the AM transmitter it transmits but it has alot of static. what could be the cause of this? thanks | ||
| Anonymous |
Good afternoon Mr.Field, I have two questions. 1.)I have a HP printer that requires 24V 400mA and I was wondering that if I use a 30V 400mA transformer will I fry the printer?? or what can I add to the transformer to lower the current and avoid this? 2.)If I use a 24V 1200mA transformer will it work for the printer or is the current too high?? thank you for your time to answer my questions | ||
| Simon Quellen Field (Sfield) |
Ohm's Law can be used to answer your questions. The current going through a device is determined by the resistance of the device, and the voltage applied (current = volts / resistance). The printer draws no more than 0.4 amps at 24 volts. We can use Ohm's Law to come up with a number that is the equivalent resistance of the printer (a printer is not a pure resistance, but for this example we can treat it as one). Re-writing the above formula, we get (resistance = volts / current), so the "resistance" of the printer is 24/0.4, or 60 ohms. Putting 30 volts into the printer would cause 0.5 amperes to flow through the printer, which is probably not safe. When a power supply is labelled as producing 400 mA, it means that it can produce up to that amount. If nothing is connected to it, then there is no current at all, so clearly it is not producing 400 mA. If a high resistance is connected (say 10,000 ohms), then the current will be 24/10000, or 2.4 mA. This means that the power supply that is labelled 24 volts at 1200 mA will be able to supply up to 1.2 amperes, but when attached to the printer (which has at least 60 ohms of resistance) only 400 mA will be used. It is possible that the printer will try to draw as much current as available, but this is highly unlikely. If you are worried about this, you can put a 60 ohm resistor in series with the power supply, so that no more than 400 mA can ever be delivered to the printer. | ||
| Anonymous |
Does the Sonic Nausea Device a noise that we can hear? Or is it too high pitched that we cannot hear it...? | ||
| Simon Quellen Field (Sfield) |
I would guess you are referring to this site. While your questions should be directed at that site, not this one, it does say on their site that the high pitched sounds are hard to locate, indicating that you can hear them. | ||
| justine aquino (Mnado) Advanced Member Username: Mnado Post Number: 66 Registered: 12-2005 |
a human ear cannot hear 10 hertz below if you're watching discovery channel you might have watched mythbusters([wed 9:00] [sun 6:00] [mon 6:00])there a myth called brown note you might not be able to hear the sound but it will make you go pooo..and they explained that 10 hertz below is beyond the hearing of a human ear. | ||
| justine aquino (Mnado) Advanced Member Username: Mnado Post Number: 67 Registered: 12-2005 |
simon can you differentiate npn and pnp transistors for me?cause i've collected hundreds of transistors not knowing what they where used for and i found a simple fm transmitter but the transistor they used is different is shape(its round and silvery)not like the transistor you used in the "free space laser data transmitter ",for short is it different or the same or can i use any kind of transistor i like..thanks dude pls reply to my e-mail "arklite_caim@yahoo.com" | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1497 Registered: 12-2004 |
The multimeter we sell in our catalog has a transistor checker built-in, and that will tell you PNP from NPN, among other things. |
