RF

You mean any sort of binary modulation?

It is a stupid idea to use h bridge for creating rf signals right? I could just use comps out for that if it really worked . And yes for binary or any analog signal. Does it make any difference?

There is no point in using an H-bridge for carrier generation. They're used for driving heavy loads. There are many options; colpitts, heartly, clapp, armstrong, pierce, and even square wave smoothing which can generate sine waves. Which modulation do you wanna use? AM, FM, DSB, SSB, BPSK, QAM, BFSK, BASK, DPSK, PAM, PCM?

Or you may use an LC circuit along with an opamp. But I prefer using transistors like BF494.

@methamafoz, what is "an rf circuit" for you? There are millions. What i know from you and your knowledge, the field of RF is not what you should go into. You say "you need to design" why??? To learn, because a custom request you, for fun, why? You have to less experience to go into RF now, start with the basics. Check the question i have here for you!

@fatcat2, BF494 Are you sure?

Pretty sure, I have a couple of those.

but they are definitive NOT for RF

Upto which frequency can we use them?

Thanks to @fatcat2 now i know there are different modulations for rf and now i will look them up on internet to learn which is used for what and what are the advantages and disadvantages. And i will try to learn how to use an opamp to use along with an LC circuit. I will definitely check BF494, too. And @hurz look at what you have written. You act as if a private tutor trying to sell every bit of information you have. I want to use an RF circuit for a very simple application. I make quizshowbuzzers and sell them for 500 Turkish Liras around 70 dollars usually for free. There are many cables when button number increases so i dont want those cables. I used bluetooth modules and rf modules for that. It worked but it was also very costly. I am ttying to reduce the price and along with this i am trying to learn. So i am going to use that curcuit to send a binary id signal. Then chexk which button has sent the signal first in the main curcuit and light up an LED to display the first buzzing button.So hurz what do you recommend? Is there a very cheap way to do it without using expensive modules. I will have around 10 buzzer buttons a box for reseting the buttons. So buttons will be used as a transciever. Making it a transciever is the second step for me sondont tell me you cant do it by just sending signals.

I think you're relying upon a modem. They are obviously costly. But you can buy cheap DIP ICs and implement an AM or an FM circuit. I suggest you to start with AM. Crude diode and transistor RF mixers can be constructed using discrete components but an IC is obviously a better option. Good luck! For your application, use a PSK module. That's because you're dealing with binary numbers. But it seems that your circuit would be pretty complex. If noise and lower speed is not a problem, you can use ASK because they're easier to implement. PSK requires balanced modulators and clock recovery circuits (which in turn contains a PLL) which will surely make your circuit more complex. By the way, didn't you search Amazon or so?

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But @methamafoz said, "I make quizshowbuzzers and sell them for 500 Turkish Liras around 70 dollars usually for free". That means he's young? For beginner purposes, BF494 is ok. I have seen lots of RF experiments with it. Of course, it is an old package in a cylindrical can but I like them.

RF is a wide range of frequency and application

The title says "RF". The description asks for increasing frequency without quartz. And the components available to make a bridge cct. @methamafoz seem ti be at the begining of a cinfusion tour. an Am modulation is cheap for shortush range and codes could be sent. You can buy them for a few pounds.. Or strip a car lock remote control.. But before 1st. Why!?

I think he rather wants to learn stuff. And that's why he's a member of EC.

Do you think its a good idea to start with RF when you want to learn electronics?

Not at all. I have no clue why he put a1nH inductor in his circuit. But still, he made an astable multivibrator using an RC timing circuit along with a Schmitt Trigger. Also, he should check more circuits using H-bridges.

Hurz RF means radio frequency generating curcuits to carry some signals like analog or digital. There are many ways to generate it. Actually too many ways . Thats why i am trying to learn from more experienced people. As i said before i want to make such a curcuit for quuzshowbuzzer projects. I know that i need to know many things before i go into such curcuits as they requires a lot of calculations and knowledge. And i know you are the best electronic engineer of the world. And i dont know the terms you know and i fool my self when i ask for help. But some people can understand what i say. Without humiliation they approach constructively. Let me explain you again if you still havent understood what i need with some basic simple terms that are away from engineering .

Lets say I have a quizshowbuzzer curcuit. I use arduino or i sometimes use transistors to make it. This time i have arduino nano inside. There are ten players which means there are ten buttons and that means there are ten cords connecting reset box(the box arduino in) with buttons. The buttons also have a power led inside indicating who hit the button first. There is also a buzzer sound in the reset box. The cords are at least 3 meters long and there is chaos everywhere because of those cables.

In the past i used bluetooth to clear the cords. It worked fine. However bluetooth module that i used is hc05. I had to use 20 of them and i used one extra for controlling through my phone which made ot 21. When i made a calculation, yes it was cheaper than many show designs in the market but was still expensive. I want to use such an effective curcuit that everbody can afford it. I make them and i give it to schools. I get the money that i have spent for them. I believe those modules are more stable but i think there s a way that i dont need to use 21 bluetooths together. (I know that i can connect 7 bluetooth as slave to one bluetooth but in my case it didnt work as it caused a lot of delay)

It just needs to transmit the id number of the button. Receiver curcuit must be able to receive from 10 other buttons. So the reset box will understand who hit the button first.

So my question is is there a simple way to design such a curcuit with some basic components (not modules). Is this a must for me? No. Am i ten years old? No Am i an engineer or someone who understands everything in electronics? No. Do i have to start with basic electronic? I dont think so. When someone tells me start with this or have a look at that. I research learn and implement. This is the way i learn and go forward in my work.

In the curcuit i asked three questions probably not relevant to my solution. I believe i asked the wrong questions. I can understand that. I asked the wrong questions because i dont want someone else to do my job. I want to learn and work on it. If you rhink i asked the wrong questions you can simply ask me what i want to do with this curcuit. I will explain you. Could I explain my self mr. @hurz?

<underestimation off> You can use Arduino Particle Photon which is capable of connectivity. Why do you use 20 modules? The person who hit first is determined by the Arduino. A pulse is emitted for a duration or until you press reset. Use a simple encoding logic circuitry to generate, say 2 bytes of the code which is unique for each module. Then modulate and transmit it. You may use ASK/FSK (prone to noise, low spectral efficiency) or PSK/16-QAM ( complex and complicated). In ASK, you transmit a binary 1 as a sinusoidal wave for the given bit time. A 0 is transmitted by not transmitting any signal. For reliable communication, use an asynchronous protocol so that the start and the end of the data bytes are known. Now its your decision to select which modulation to use. I will surely help.

What frequency of operation do you desire?

http://everycircuit.com/circuit/5402930113675264

So what i understand from the curcuits you shared i will build a carrier signal first then when i send signal carrier signal will be on and the receiver will understand the button is pressed. And if the frequency is high enough i can send a binary signal that identifies which button is pressed. We dont need to know about if other buttons are on or not. If i understand until here is true, what happens if two buttons are pressed at the same time. Will it cause a problem?

The circuit which I shared with you is amplitude shift keying aka on/off keying. A buffered binary signal is fed to it. If you want to determine which person pressed it first, the usual way is to assign various frequencies for each button. But this is a very tedious task. One problem with ASK is that the signal should always begin with a logic HIGH as it cannot differentiate between a logic LOW and a no-signal condition. So another option is to use encoder and 1-of-n decoder ICs where n=log2(no. of persons/buttons). I may search out a pair of such ICs for you. SER/PAR converters are also required. Of course this setup can be implemented easily but the Amazon_module option is obviously the better choice! Does your Arduino emit different codes for each button press?

The SER/PAR device I am talking about is a bidirectional shift register.

The annoying (yet tolerable) thing is that you respond so late. If this pattern continues, your problem won't be resolved before the lockdown is lifted!

I know that you are busy with your work but I am losing my patience at a -120dB/dec. rate. I have seen one thing; that you respond after a long time only. I will wait for one day. If the response from you is still null zero, then I will unbookmark. 😐

UNBOOKMARKED

😶

Sorry for delayed answer. We had a covid suspect in the family. I am using arduino nano , pro or uno. I can change the codes anytime to diiferentiate the signal. Usingbdifferent frequencies will be a tedious task as u mentioned. Decoders and encoders are welcome but arduino will do this job in any case as long as i program it well o think. My problem is to transmit the code. The problem ASK here is what happens if we press all the buttons at the same time. If the frequency is high enough i think it will be difficult to do that and i think i can add a few things to the codes to prevent this. I dont know i had a fewbthings in my mind butbwhile writing i realised it is bullshit. Let me think and write here. I am wondering now how bluetooth modules do it. They use some IDs before they send the data i think. So bluetooth receiver decides if it should receive itbor not. Am i right? It doesnt cause any problem when two bluetooth slaves want to send data or connect to this device. Cant we do the same by adding some initial codes to the transmitter and receiver arsuinos?

Yeah; its true. Bluetooth uses various types of "Super complex protocols" (Electroboom!) but the main problem is to transmit those, especially if the word length is high. If you are making lots and lots of modules, you may use 8 bits (256 unique possibilities). Protocols aren't necessary here as it is a simplex device, i.e., it only transmits data. The person who pressed the button first will make the arduino transmit a unique code. Is it an 8 bit code? I would recommend using a bidirectional shift register IC and a crystal clock. Wait, I will help you. I am presently finding a suitable IC in multisim.

Jeez, I am really sorry @methamafoz. Hope you and your family are fine. Everything will be alright soon 😊

Thanks @fatcat2. I hope so too. I will check what you proposed as well now

Check this PAR-SER converter:- 74F166 IC.

How many bits (length of code) does the arduino output? I think you would have to reprogram your code; always start with a 1, a HIGH. This begins the process. You would have to generate a clock.

For the receiver section, you would have to use a crystal/RLC BPF.

Why do yoy worry about simultaneus transmissions? Only one signal will be transmitted serially.