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hello sir , i am making a project of transmitter.whose circuit diagram is shown below.i think this circuit diagram is right for me so i choose it to build my project.but there is one problem comes across me .i've found that i have bc547,bc548,bc337 type transistors only but the recommended transistor in this circuit diagram is bc338 which is not available in any shop in my town..so what can i do ????? can i am allowed to use transistors bc547,bc548 or bc337 in this circuit.actually i have taken this image from a video so the suggestion of using bc338 is given in the video..not given here in the image.the +9v dc input is given in the junction of coil,0.01 micro farad capacitor and 27 ohm resistor. -ve terminal of the battery is connected to the ground one terminal of audio input is given to the -ve terminal of 1 microfarad capacitor and second terminal to ground .....please suggest me solution as soon as possible ..i have to complete my project till next morning.....please also tell me the description of the full circuit step by step....thankyou very much sir               here is the image of transmitter made in the video..

Hello,

     I would like to wirelessly sync my Altera FPGA DE1 board (Cyclone II) with another circuit as part of a project. Please help with whether or not it's possible, then what parts I would need for the build. I will only need to sync 1 byte (8 bits) at a time. Should I use a Wi-Fi card, infrared LED's, or bluetooth. I would like some help with the sync part only. Thanks for your help.

              Robert Newstrand

Hi Chris -

I am a not an engineer but I have a product idea which I would like to build that involves the idea of a wireless beacon. I am not sure if there are engineers (for hire) or companies that can create a product based on an idea you have to build it? Would appreciate any recommendations.

Meanwhile, the idea I have is for a small (light/pager) size wireless beacon that must be run on a battery and is able to connect to a network (ie. phone or pager) independently upon power on.

All help will be greatly appreciated.

Thanks.

Chris Hi,

I was wondering have you any experience of IPTV and the use of Roku receivers?

Martin

New question:      Here is something I cannot figure out:
I am an electronics engineer. I can design and build circuits if they are not too difficult. I can build audio stages and, I assume, we are all familiar with the design philosophy of the superheterodyne receiver.
If on a bench, I throw together several audio gain stages (each has a gain of 10), somewhere around three or four I start hearing noise. This is amplifier noise, likely thermal and it means at gain of 1000, I have hit the noise floor. At this point adding more gain stages is futile because it only makes the noise louder.
This is the point in radios where the detector is found. From the detector going forward the frequency band being amplified is changed from AF to IF or RF, an increase of about one thousand in frequency. There are usually two or three gain stages of IF. For some reason this does not increase the noise as the previous experience suggests. Instead the noise floor falls away and finally, as one moves along to the front end, receiver sensitivities around a microvolt are obtainable. This means the noise floor has dropped by a factor of a thousand.
I can not understand how this can happen. According to thermodynamics we are on the low side of a black body curve which is flat up to infrared frequencies. So in any interval of say 15KHz bandwidth we should see the same noise power wheather it is in the audio range or the RF range. If this was the case radio would not be possible. So clearly something strange is happening and this has been well understood for more than 50 years.
What is the explanation?

Sir,

I am using a SIM 300 module . Could u please help me with capturing the tower information.

Hello Chris !

I look for RFID tags which can be detected by a RFID over 1 meter distance. It's for a wine cellar management. For example, i wish (if it's possible) to take out a bottle without approach it towards the reader....

I would like use Raspberry PI connected to RFID system with tags which have a long range (between 1 and 2 meter).

Is it possible ? Can you help me for equipmenet choice ?

Thank you

Hi Chris

I've just unpacked my new Raspberry computer and quickly tested it using my TV.

It seems just like the day when I plugged in my BBC computer many years ago. Sigh...

Then my wife handed me a slip of paper (the only documentation supplied with the bits & pieces)

It had escaped my notice. I read it and it carried compliance information.

I must admit that I've never read this sort of thing before, but squinting hard to read the small print, I see that the Raspberry  computer is not designed to be used in a residential area, only in a commercial environment.

For example, one of the statements declares that at my own expense I have to stop the thing from interfering with radios.

In fact, I believe the slip of paper should be headed "Non-compliance Information" rather than "Compliance Information".

If it's intended for use in a home environment then it is NOT compliant with the appropriate EMC requirements of the various countries in which it is sold.

I wonder how many users have read and understood just what is said on the (back of the) slip of paper produced by Farnell?

What do you think Chris?

Is it just another source of problems for radio listeners?

regards

Allan

Hi,i 'll use face recognition in my project and i intend to use web cam to take pictures of people who 'll enter a building .these pictures are videos and i want to connect the cam with computer wireless by access point (WiFi) so,i need your help.is it possible? i exactly want to khnow how to connect web cam to computer but wireless .is there any interface 'll be between them? i need your help.it's an urgent need. Thanks

help,i 'll use face recognition in my project and i intend to use web cam to take pictures of people who 'll enter a building .these pictures are videos and i want to connect the cam with computer wireless by access point (WiFi) so,i need your help.is it possible? i exactly want to khnow how to connect web cam to computer but wireless .is there any interface 'll be between them? i need your help.it's an urgent need. Thanks