I’m starting this post thread to discuss building minimal radios. I’ve always found them fascinating because even though they have the same principles, how you make them is entirely up to you. You have to follow the basic circuit design with to start. That is important to understand.
Now, let’s get started with the first one that I came across. I consider this one to look simple, but what I am going for is one where we don’t need as many parts. This one is courtesy of https://openideo.com/challenge/amnesty/inspiration/improvised-radio-transmitter and has a few parts that you can get fairly cheaply.
Building circuits takes some time and buying is sometimes cheaper than you get the parts for. There was a time where I liked to build circuits because it was fun and was a learning opportunity. But now with everything you can buy out there, you can be well on your way to doing some more interesting things.
I like to purchase a lot of my electronics projects from Amazon. You can get deep into their integrated controllable circuit systems. Those are fun to use and can help you teach your kids a lot about electronics. Snapcircuits is a great learning aid for kids if you do it right.
If you are looking for good electronics programs and instruction located in India, here is a list of resources to get you started at the end of this article. First, though a couple of key questions.
- Be prepared to answer why you would like to attend electronics school. What is your objective for learning electronics.
- Have you done any work with electronics before in India. Do you know what a potential job would be like in India working in electronics?
When shopping for a ham radio antenna analyzer or arial analyzer as some call it, it is goodo to consider the AIM 4170 Antenna Analyzer. Before buying it though, please review some of the details about the AIM 4170 antenna analyzer. Those are listed here below. Antenna analyzers can be very useful when building ham radio antennas. I know that often times I would construct an antenna by doing the measurements correct and cutting the feedline to the right length only to get high SWR on my antenna. A good quality arial analyzer can help you get a low SWR and that can make your time on ham radio more enjoyable. You can purchase antenna analyzers from a variety of places and you can spend little or lots of money on them. I haven’t seen too many antenna analyzers though that cost less than several hundred dollars. That may be a bit discouraging but it’s a great tool to have. I have purchased my equipment before from Ham Radio Outlet. They have several locations around the country and have very good service. The AIM 4170C Antenna / Lab RF Analyzer has many features from a small box. Here are some of them:
- SWR referenced to any impedance
- Resistance and reactance at the cable input
- Resistance and reactance at the antenna terminals
- Resistance and reactance of discrete components
- Return loss
- Reflection coefficient
- Cable length
- Cable impedance
- Cable loss
- Distance to fault (open or short)
- Smith chart display
- Quartz crystal parameters
I think some of the valuable ones for beginners are calculating the cable length and the cable loss. SWR is key but sometimes we don’t realize how much is lost on cable resistance. A Smith chart display can be very handy as well. (For more information see http://www.arraysolutions.com/Products/AIM4170B.htm) You can also read the reviews here http://www.eham.net/reviews/detail/6258.
This is a review for the Palstar ZM30 Antenna Analyzer. When you buy something from Palstar, you are buying a product from a good company. Palstar’s customer service is very good and their quality is good as well. Many people I know speak highly of Palstar and their products. The Palstar ZM30 Antenna Analyzer is no exception.
Here are all the technical specifications on the Palstar ZM30 (http://www.palstar.com/ZM-30_specifications.pdf) . The main reason to get an antenna analyzer is to help tune your antennas. So in my mind, you want that piece of equipment to have a good working range of signals to work with and good attachment points on the analyzer so that you can hook up your antenna easily.
One thing I like about this model is that you can plug it in the wall or run it off of batteries. That’s a very nice feature. Usually signal generators will run down on power quite a bit. It takes a good amount of energy to gererate signals for reading. One analyzer I built chews through batteries.
The other thing I like about this antenna analyzer is that it is not priced out of reach. That is always a plus. The controls are easily managed in the front. They give you almost an IPOD type control knob for frequency adjustments. All in all, a very good product.
Purchasing an antenna analyzer can be very expensive. Analyzers range in price from $300 up to $10,000 or more. Come on folks, this is a hobby here. I wish I had that much money to spend on ham radio. Thankfully there is an antenna analyzer kit put out by a ham radio club in Australia that is wonderful. It’s the VK5JST AERIAL ANALYSER designed by Jim. (See notes at the end of this article for how to order and contact the ham radio club)
Let’s jump to the finished project: This kit is for advanced builders which I wasn’t when I ordered it, but how do you get advanced, you build. So I built and it wasn’t really all that difficult to build. The first thing you want to do is block out some time and get some old movies to watch while working on it. I think I watched like 6 and by the end was getting a bit delirious. Since I’m a newbie at this, I’ll offer up my notes here and documentation on my building process. I hope this helps out someone. First off, you get a package with a lot of little parts. Hence, the word “kit”. At first you might pull your hair out but relax and the first thing you want to do is go through and check your parts. Do you have them all? Check against this list: http://www.users.on.net/~endsodds/partsmk2.doc Next, print off this component overlay: http://www.users.on.net/~endsodds/ovrlymk2.jpg I took a red marker and when I put a component in, I highlighted that component on the board to mark it done. I also marked off the components as done on the parts list after I got each on or each set installed. Here’s my cheat sheet for the resistor color codes. It helps when looking at them to look at this sheet. Of course, unless you have memorized all of those color codes. The little square pins threw me for a bit. I didn’t know what those were for. There were for test leads. I guess I could have figured that out. Put those in first, then solder on all the resistors. Then do whatever you feel like soldering in. Save the big black IC’s for last for installing but go ahead and solder in the dip sockets. There are two little wires on the component diagram showed wrapping around the positive and negative test terminals. When you are pretty much all done soldering, solder those on there. I didn’t have them soldered on and the thing wouldn’t work. When you solder in that LCD, you could follow the instructions that tell you to cut wires really little and then slip collars over them. I tried that, couldn’t get it work. Instead just solder wire directly into the hole on the board first, guess at some length you want it to be and cut it off. Just do two of them first though and start long. It is sort of like cutting hair, it’s easier to take off than put on. For the box cutting out the holes and everything can be time consuming. If you have a Dremel you are in great shape. If not, go buy one and save some sanity. Click here, http://www.users.on.net/~endsodds/analsr.htm for details on the analyzer. There is also a link on that site on how to order it from the ham radio club in Australia.
Here are some additional images of the finished product. This is the top right section of the analyzer:
Here you can see the frequency control in the center of the dial. I’ve attached a few wires with power coming in for a test.
This is a closeup of the back of the dial area.
A photo from a distance away.
Some of the integrated circuits listed.
That’s all there is. Definitely a fun project to do.
Subcarrier FM transmissions can be picked up by creating a circuit that identifies them. The circuit would not be the easiest to put together quickly. However, it is a doable project. I would start with some simplier FM receivers first to learn how they work and then progress onto this one.
If you ever wanted to build a very small FM transmitter, then this is the circuit for you. With only 16 components, this is a very compact FM transmitter. I like small circuits because they give you a chance to build something quickly. Sometimes if you pick a project too large, then you can’t get it done.
If you would like to pick up the parts before building, here is a list of the parts for this small FM transmitter.
Two 100K resistors
1 10k resistor
1 470 ohm resistor
2 470pF capacitors
2 4.7µF, 16V, electrolytic capacitors
2 4.7pF capacitors
1 4-40pF trimmer cap (this is optional, but if you are putting in an order to Digikey for electronic parts, just go ahead and get this as well.)
2 2N2222, NPN transistors
1 Electret Microphone
1 9 Volt, Alkaline battery, or you can use a 9 volt power source.
I like to create these projects on a breadboard first. If you can, purchase a good breadboard kit. Here are the full instructions to build it:
Here is a small two transistor FM transmitter that can transmit up to 1/4 of a mile. That is a good distance and should not cause many problems interfering with other radio communications. There are a wide variety of applications for a small device like this. You can build one to listen to nature sounds. You can put this in a waterproof housing and put a 9 volt battery in it. However, after a while, that is going to drain your battery down. For a listening device that kicks on when sound hits a certain threshold, you need a small sensor that can pick that up. Almost like a photo sensor.
Here are the list of parts:
R1,R4,R6 = 10K C1,C2 = 0.1uF Q1,Q2 = 2N3904
R2 = 1M C3 = 0.01uF L1 = 0.1uH
R3 = 100K C4 = 4-40pF
R5 = 100 ohm C5 = 4.7pF
R7 = 1K
I would recommend buying your parts at Digikey or Mouser. Both are good parts suppliers. It all maters how low of a price you can get.
(source – http://www.uoguelph.ca/~antoon/circ/fmt1.htm)
This 3 Volt Miniature fm transmitter can only transmit for short distances, but it is small. Having a small discrete FM transmitter can be useful. If you don’t want to consume too much power or have your transmitter too visible, then the smaller the better.
I prefer working on small projects like this one because when you create small electronic projects, then you can understand how the more complex ones work. Here is the parts list:
1 – 4.7k resistor
1 330 ohm resistor
1 0.001uf capacitor
1 10-40 pf variable cap
and then you will also need an electret mike, some magnetic wire for the antenna, and then a 3 volt battery. (source – http://www.uoguelph.ca/~antoon/circ/fmt2.htm). I would buy the magnetic wire at Radio Shack but order most of the capacitors from Digikey or Mouser. Variable capacitors are handy to have as well.