Transmitter design Interview Questions 

I searched on the internet to find chips to design a system that send sms.
i traied to find GSM chip and SIM reader but i failed
are these chips exist?

i want to design something that can measure the distance of an oblect using a microcontroller. what i have thought of is .. when i press a button a pin of the micrcontroller(uC) will go high. this will lead to the transmission of the ultrasonic waves from the transmitter. at the same time i will start a counter in the microcontroller which wil increase every micro second. when the receiver gets the reflected signal it make one pin high or rather input some signal to the micrcontroller. when the uC receives this signal the counter will stop and a distance will be calculated based on that counter value.

can anyone please tell me wether this thing will work or not.. also i want to know how to generate soun waves from that transmitter.. will it just start signalling them as soon as give them the required voltage? .. also what happens when the receiever gets those waves?.. is there any voltage difference or something like that...

any help will be greatly appreciated

I don't need anything fancy as the 50mW is more than I need so losses aren't a problem. I'd like a model and place to buy in the UK or a design. Thanks.

see again oh my god why you always ask so much difficult question. Now i don't know. Next time ask some easy questions which i can answer.

I have an old pair of RCA infrared headphones + transmitter that I use at home with home AV stuff. I want to get an extra set of headphones. There are a lot of brands out there now, and various models. Most are designed to work with in-car TVs. Wondering whether this kind will be compatible with my home-type transmitter, and whether I can use two headphone sets at once.

I have a Zune, and I want to get an FM Transmitter that will play it through my car stereo. I don't have an input jack on the stereo, or a place for a cassette adapter, so I need to transmit via FM. The only problem is, I can't seem to find one that works well enough to justify spending the money. The Belkin Tunebase was my first choice, but I heard the Signal it transmit is super weak, so you get either no transmission at all or alot of static. I love the design though, it's exactly what I wanted, but it's pointless if you can't listen to your music right. So, anyone have an FM Transmitter that is ultra awesome, and can maybe point me to a website or two where I can read up on them? Otherwise, I may have to go get a new stereo installed in my car, which is not what I want to do. Thank you.

I am trying to pick a good FM transmitter for my iPod. Many of the stronger units attach at the bottom and I don't think they will fit in the area designed for the lighter in my Honda (it is a 4 door model).

Did anyone try the hondalink? I was told that my car was too old. Also did anyone just get a line put in their car instead of using the FM transmitter?

It’s really an inconvenience to have to turn on the transmitter every time I get in my car so if I just leave it on in the background so when I get in the car the only thing I need to do is turn on the radio to receive my music. I’m just afraid the phone was not design to transmit for long periods.

It's a physics project.

Experts please answer ... Thanks in advance !!!!

I am trying to build a radio transmitter for my science fair project. Our design uses a 1MHz crystal oscillator and a 8ohm to 1k ohm transformer on a solderless bread board. But the shops in my area don't have 1 MHz crystal, they only have 4 MHz. Please tell me of an alternative model which uses 4MHz oscillator. I cannot buy stuff from the internet.

160 -190 KHZ band of frequencies are for experimental no license in the U.S that have certain regulations for power output and antenna considerations. I can build what i need, and have done so in the past, but i would like to see your ideas and diagrams.

You're asking a question about something that has been in use for longer than I have been alive, and I am 55. ALL receivers use frequency discrimination, it's part of the selectivity function of a receiver. You don't want a broad band receiver circuit because then you would have everything available coming in through the receiver. That would be a very good example of bedlam, or incoherent noise. Let me put it this way, do you take ALL of your music and play everything at once? Hopefully not, you select 1 song, listen to it, and then choose another, listen to it, and so on for as long as you choose to listen to your music. Receivers are set up to do the same thing, they select 1 channel at a time as the operator chooses. When done, the radio is tuned to another frequency. Transmission is done in the same way, 1 channel at a time. While commercial systems may transmit many separate lines of communication at the same time, it is all bundled into 1 channel for transmission. I believe that you would profit in understanding what you are asking about by getting a copy of the ARRL Handbook for Amateur Radio from either the library, or buy one, and read up on radio transmitters, receivers, and the practice of radio communications. It would clear up a lot of misunderstandings that I believe that you have. The wording of your question indicates to me that you haven't a clue about what it is that you are asking about. Here is a point for you in that regard, define SSB. What is it, and what are the operating parameters of such a transmitter. Further, could an AM or FM receiver detect and reproduce the audio signal being transmitted. These are very simple questions, but if you don't know, then you need to know before embarking on your project.

it should work.. any engineerin student who already did tat well can help me... fm transmitter n receiver circuit design...

there are many different transmitter designs on the web. i want to make a cheap 1 with at least a few feet of range. i dont want to waste my time making 1 and it doesnt work. help plz