| Author | Message | ||
     Mark Alliet |
i need to make a 3vlot amp to connect to my radio and to a 8ohm speaker for my science fair progect: URGENT!!! can you please help me? | ||
| Simon Quellen Field (Sfield) |
There's a farily simple amplifier here. Others get a little more complicated. Things get simpler again if you use an integrated circuit. Other links: here here here You can also just buy a cheap amplifier at Radio Shack, such as their part number 277-1008. | ||
| Anonymous |
if you put a rf power amplifier between the oscillator and the antenna on the am transmitter will the siganl gain strength. Is an rf power amplifier the same as any of the amplifiers from the previous post? Will I need an amature liscence to do this? Thanks | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 413 Registered: 12-2004 |
If you register as a user, you can turn on the spell checker. The amplifiers in the previous post are audio amplifiers. They work with kilohertz, not megahertz. Do a Google search for "simple rf amplifier" to find hundreds of simple circuits. And yes, you will need a license. A commercial licence if you plan to stay in the AM band, or an amateur license if you move to a frequency in the amateur bands. | ||
| Twors (Twors) Member Username: Twors Post Number: 15 Registered: 7-2006 |
I made the toy at this site: http://www.sciencetoymaker.org/SpeakPhone/assembl.html Ok, so it's very simple lol. Two speakers connected to make a mic and speaker. That's it. The sound is so weak and a very deep low pitch. Is there a way to amplify it as simply as this toy is made? | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1564 Registered: 12-2004 |
The Integrated Circuit Amplifier project will amplify that nicely: "http://sci-toys.com/scitoys/scitoys/computers/solderless/ic_amplifier/ic_amplifier.html" | ||
| Twors (Twors) Member Username: Twors Post Number: 16 Registered: 7-2006 |
Hey I just thought of something about that ic. Would it be possible to make a similar circuit board with aluminum foil and cardboard? I know foil conducts electricity decently. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1565 Registered: 12-2004 |
That might be a little hard to solder something to... | ||
| Twors (Twors) Member Username: Twors Post Number: 17 Registered: 7-2006 |
I know XD | ||
| Bruce Lee (Unregistered Guest) Unregistered guest Posted From: 65.57.245.11 |
I know Karate, Jujitsu, Aikido, and a whole bunch of other Japanese words... | ||
| Twors (Twors) Intermediate Member Username: Twors Post Number: 24 Registered: 7-2006 |
So, according to the site plans for your ic audio amplifier, one speaker has the red connected to H-27 and black connected to ground. Now I need to know where to put the other speaker's wires. And after that, if I talk into either one, it will go to the other, or is one speaker output and the other input so I would need four speakers? I'm talking about the post six up from this one. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1575 Registered: 12-2004 |
You would want four speakers and two amplifiers. Each amplifier would use a speaker as a microphone. It would connect where the three penny radio connected in the text. | ||
| Twors (Twors) Intermediate Member Username: Twors Post Number: 25 Registered: 7-2006 |
Thanks. Will heavy heavy humidity ruin this system or the speakers even if amplifier is in safe place? Oh and about the power usage, the battery won't run out too quickly if permanently installed or should there be a push to talk switch? | ||
| Twors (Twors) Intermediate Member Username: Twors Post Number: 26 Registered: 7-2006 |
There is an electricity buzzing noise of the power supply (adapter 500 mA). It buzzes heavily at 3 volts setting but at 4.5 and above, it's not so bad, but I can not hear anything else except when I tap the microphone. How do I get rid of the buzzing? Different speakers? Would the capacitors and resistors modification change that? (Message edited by TwoRs on November 7, 2006) | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1577 Registered: 12-2004 |
Your power supply is not properly filtered. A good one will be more expensive. Use batteries, and you won't have the noise problem. | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 205.188.117.8 |
Is there a way to amplify only a very small range(+/- 5hz) of frequency? I'm working on an IR, on/off, controller. I'm thinking of sending out a certain frequency in IR. Then using a phototransistor to recieve the "coded" light. Then use the amplifier, which now only will allow a few frequencies to pass, to then trip a relay. Is that do-able? Thanks, -Randy | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1722 Registered: 12-2004 |
Sure -- that's how commercial IR receiver modules work. The carrier is a 38 khz pulse train. The narrower the bandwidth, the fewer bits of information you can send per second. With 10 hz of bandwidth, you won't get a very high signal rate. | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 64.12.116.8 |
Yes I understand that they can do it... But I'm wondering how could I do it? As in; how does it only respond to 1 frequency" Thanks, -Randy | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1726 Registered: 12-2004 |
The same way a radio tunes into a single frequency. Read the Radio chapter to get a better understanding. Then Google for "bandpass filter". | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 152.163.98.177 |
OK thank you Simon, oh and on that radio note... I had something weird happen to me other other night. I was transmitting sound via IR. I had it hooked up just like the LASER transmitter. But then when I took off the leads to the LED it continued to play when I cranked up the volume a little higher(was using an el-cheap-o sound system). It would be louder when I touched only one of the leads that went to the LED or when I grounded it. Was wondering if that acted like a radio at a low hz? -Randy | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 152.163.98.177 |
Ok thank you Simon, oh and on that radio note... I had something weird happen to me other other night. I was transmitting sound via IR. I had it hooked up just like the LASER transmitter. But then when I took off the leads to the LED it continued to play when I cranked up the volume a little higher(was using an el-cheap-o sound system). It would be louder when I touched only one of the leads that went to the LED or when I grounded it. Was wondering if that acted like a radio at a low hz? -Randy | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 152.163.100.68 |
anyone have an idea as to why? | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1735 Registered: 12-2004 |
It is easy for an amplifier to become an AM radio. There are plenty of wires to become antennas, and plenty of diodes around to act as detectors, and lots of amplification to boost weak signals. It is also easy for something like the laser transmitter to transmit AM signals. Diodes and dirty connectors can mix the audio signal with noise, creating a modulated signal on all bands. | ||
| Randy (Unregistered Guest) Unregistered guest Posted From: 64.12.117.8 |
Ok thanks Simon... it was just really weird.. I was listening.. then I took the clips off and it still played very faintly. I was surprised.haha thanks, -Randy |
