Now solder a wire from the junction to U1's collector pin refer to the schematic. You can now connect your MP3 player! I'll post an additional step regarding this mod. This project would still operate at voltages between 7vv, so yeah it's compatible. If you want to stay safe and prevent the circuit from burning, solder a 10 ohm resistor in series with the FM transmitter and 12v battery. Just don't use it near an airport. For more info, pleas read the FCC Rules.
This post was selected by Instructables staff for ThrowbackThursday on our social media channels! I made this on a Saturday afternoon with my 9 year old Son, took about hours and we built it on perf board.
It works very well indeed. Thanks for posting. Question 4 months ago. Question 8 months ago on Step Is it possible to tune this to work on frequencies lower or higher than the standard 87 to mhz? Answer 5 months ago. Question 5 months ago. Reply 8 months ago. Question 1 year ago on Introduction. Hello, I have difficulty in making coil. Can I use a copper wire?
If yes what should be it's thickness and how many turns I should make the coil. Please give me some suggestions. Answer 8 months ago. Question 3 years ago on Step Can I use anything else instead of the 40pf trimmer capacitor? I can't find it. Please give me the solution for this. Answer 1 year ago.
Question 3 years ago on Step 9. Antenna can be made of any insulated wire. Gauge doesn't matter in antenna for such small circuits. More by the author:. About: Hi! I am Angelo, others know me as TechBuilder. Instructables has been my home ever since I was Hope yall enjoy my projects! My Experience: FM transmitters remind me of my early years in electronics. This allows the circuit to yet again begin flicking across its a couple of stable states.
The first of these states is the condition where the U1a output remains high and the U1b output is rendered low. The second state is that condition where the U1a output turns low and the U1b output turns high.
The function of capacitor C1 in this CMOS transmitter circuit is to regulate the speed at which the changeover happens between the two states. If the capacitor hadn't been used, would have caused the circuit to oscillate at an abnormal, and incredibly fast rate. This would have also caused the frequency to get unstable due to varying room temperature, the wire dimensions that join the circuit with each other, and even with the proximity of your body part to the IC.
This is exactly how C1 handles the frequency of the flipping states: As soon as U1a flips and attempts to switch the circuit through the 1st state to the second state, C1 holds the circuit within the first state for a short time, by doing so helps to reduce the frequency. The capacitor is able to do this since it is coupled to the input of U1a, in the same way as R4 is. So long as C1 is in the charged up condition, it is able to "overpower" resistor R4, stopping it from modifying the U1a input.
Now, as C1 begins losing charge by means of R4, this permits U1a to topple over to the second state. If you have any circuit related query, you may interact through comments, I'll be most happy to help!
Your email:. On which frequency?? Two last things, both regarding the coil: 1 Are the dimensions of the coil wire format, diameter and length critical? Which dimensions would be optimal? Would it be wise? Hello sir. As iam a verry begginer I wanted to ask you couple questions In the verry first diagram what are 6t and 15t, also what is the thikness of the antenna and thanks for your great help.
Hello sir good evening, sir is the sound or voice transmitted by this circuit is catch by a mobile FM radio. Hey can i just put the second bug together without ground,pcb,or breadboard.
Just solder their pins together?? Sir you're second bug has an ot of What is the dimeter and how many turns? Sir I want to use 9v adapter for the 9v fm transmitter circuit. At the receiver end buzz sound comes means sound is not clear when I use it with 9v adapter. I want to use this circuit with adapter do I have to do change in adapter circuit or in Tx circuit. Hi, I want to design a simple tranmitter and receiver but for a very limited range around feets.
And at the same time their operating frequencies should be configurable. Can I do that with the one transistor transmitter and receiver circuits that are shown. How can I configure the operating frequencies. Sir, i want to ask if i can make changes to the electrolitic capacitors in the last circuit, …by the increasing not reducing range nf of capacitors. Tun, Please do not repeat your question more than once…your questions appears at least 25 to 30 times which becomes very disturbing while moderating.
Does it need to change values for other components? Referring to Ckt. Referring to the ckt with the fewest component.. Can I use 23 AWG? Thanks a lot. Is is correct sir or the components seller just sold to me the wrong transistor,, thanks. Hello good evening, I am a faithful follower of the website. I want to know if you have a transmitter and receiver RF circuit. I need to control a relay … when the transmitter is close the relay is energized, but when it goes away more or less 5 to 10 meters the relay of the receiver is disconnected.
I frequently surf the web for high power FM transmitter circuit ideas. There are too many but no one answers all the questions. Thanks again. Regards, Jignesh. Made the 2nd one that uses the antennae for a mic instead of a piezoelectric mic and it did not work even up to 5v ma. Most of the transmitter publish running on a power 3v or 9volts try reducing the emitter resistor 0hm you will see the difference in transmission.
Not bothered whether the receiver indicates with LED or sound. The reason for this is the cost of a off the shelf sewer drain detector equipment is very expensive. Can you recommend a circuit? Then, with a non-conductive tool, adjust this capacitor for the clearest reception.
Although this transmitter is designed for the FM broadcast band, it can be tuned to 2 meters, and other VHF bands by changing values of C4 and L1. After mounting the coil, back out the bolt. C1, C2, C3, and C5 are ceramic type capacitors, preferably npo low noise or equivalent. However, you can use any type you have around, but do not use electrolytic or tantalum capacitors. A 2N transistor was used for Q1 and Q2. The 2N is a general purpose silicon NPN bipolar transistor used for switching and amplifier applications.
However, you may substitute the 2N with a 2N or a 2N, these are also general purpose transistors. Students graduate with strong problem-solving and analytical skills needed to design new hardware and software systems.
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