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  1. Shahriar

    You can download OpAmp hand bokk here!

    Hi Follow the links below. when you downloaded all 13 links, then extract number one to creat a PDF. This book is in 877 pages and one of my friends has uploaded it. http://www.4shared.com/file/811501/4b4cfb69/OpAmpApplicationsHandbook__2005_part01.html...
  2. Shahriar

    4PDT to SPDT trick

    Maybe using CD4066 or CD4016 solve your problem. of course depending on Your current and Voltage as Staigen said. HTH - Shahriar
  3. Shahriar

    How to make RPM counters

    The best way for a RPM counter is What pebe  Said. Imagine if you use a Devider or revs in say 10 sec and then calculate for 1 min this problem will happen! You should multiply the number of RPM in 10 seconds by 6 to achieve for 1 min. so the Number you achieve is alway = 6K. I mean : 6 - 12...
  4. Shahriar

    Video Multiplexing system!

    Hi I want to build a Video Multiplexing device, Which can show a single video picture on a big screen which has been consist of 4 or 16 or more single screens (CRT or LCD). I have tried to show what I mean in the attached picture. This project is just like those in TV SHows that show the...
  5. Shahriar

    Library Aid Device

    Yeah, Thats right. but for using a Scanner, you need a PC for every one, and every few minutes you should put that Heavy book in the Scanner. Sometimes, There are lots of solution to do a job, But I think the important is which way is The best. If you yourself were in a library and you could...
  6. Shahriar

    3-5V DC @50mA from 230V AC without transformer

    BTW, If you don't want to build one, You can buy a Mobile Charger and enjoy it... HTH - Shahriar
  7. Shahriar

    3-5V DC @50mA from 230V AC without transformer

    Hi The circuit I have attached is from a Project in project section of this site with this topic. " Courtesy Light " you can use the power section of this project with some changes. Once I saw a project on the web with this title." Transformerless Power supply"  as I remember it has did the...
  8. Shahriar

    Library Aid Device

    Hi Have you ever gone to a Library, and when you are reading a book, you need to take some notes of the book. You have probably found it disgusting! The Problem is worse, when there is a picture in that section. If there was a device which you could take it to library, and when you need to...
  9. Shahriar

    433 MHz RF Amplifier!

    Hi I have a 433MHz TX and RX module which you should connect it to a 50ohm Antenna and enjoy! I plan to use a i.e. 1W RF amplifier to increase the output power. Does any body have a Schematic for this Power amplifier ThanX Shahriar
  10. Shahriar

    How To calculate the feedback resistors in an OpAmp Amplifier?

    Yeah, That's Right  ;D
  11. Shahriar

    How To calculate the feedback resistors in an OpAmp Amplifier?

    Hi Imagine that you want to build an Inverting OpAmp Amplifier with the Gain of 30. What is the difference if I choose two resistor as (Rf=100K, R1=3.3K) or  (Rf=10K, R1=330R). In both cases the Gain is 30, but In what conditions, does it make difference? and what about a Non-Inverting One...
  12. Shahriar

    URGENT urgent

    About the PreAmplifier I sent, I should say that, I do NOT think if it will drive a Speaker. The Output of this preAmplifer Should be connected to a Power Amplifier Like that 10W Amplifier in Project section as I said Before. I sent these, Because gogo2520  wants to build a descret circuit...
  13. Shahriar

    auto-sms

    Once I see a Project which send and receive SMS via FBUS in a NOKIA Mobile, May be it could help you. If You look it up in Web, You can find it. BTW, I have seen some Devices on the web which can send a mass of SMS, While connected to a PC HTH - Shahriar
  14. Shahriar

    I need an audio recorder/playback device

    I have Recorded and PlayBack Sound via ISD25XX ICs many times, But if you mean a video Clip, I should say NO, it is impossible with these ICs HTH - SHahriar
  15. Shahriar

    URGENT urgent

    Here the preAmplifier you need. Use Bias Resistor If you have an Electric Mic and remove it if you have a dynamic Mic. You can Find the Power Amplifier from the Project section of this site. It has used a NE5532 and a Push Pull at the output. I have built these two and works very well. HTH -...
  16. Shahriar

    Need Help Alligning IR lasers

    I have not done this, but think about it.... Use a laser Pointer (Those use in Conferences) and fasten the pointer to the IR Tx. then Once you adjusted RX and TX when they are close to each other, then Mark the Laser pointer Somewhere on receiver. In this way you can adjust them in far...
  17. Shahriar

    What kind of Electronic related devices are good to work as a job?

    Hi One of my friends (who has enough money) and I want to start a new job. we have disscused very much about what kind of bussiness we begin. At last we agreed to find a factory or company in another city or country(litttle bit difficulat) and tell them that we can sell their products and give...
  18. Shahriar

    Small Cap between OpAmp Input Pins?

    Hi In the following picture which belongs to a Tone Control Circuit, Can anybody tell me what that Small Value Cap (10pF) Is for? Between In+ & In- Pins I remind I saw the reason somewhere Once, but todayI looked it up in all my books, But did,'t find that. I guess it is some how...
  19. Shahriar

    3uH Inductor at the output of PowerAmplifier?

    Hi In the following picture which belongs to STK4121 Power Amplifier IC, Can Anybody tell me what that 3uH Inductor at the output is for? In Car Power Amplifiers, there are some big Inductors wounded on a big Core, Are they the same as this inductor? ThanX in advance Shahriar
  20. Shahriar

    Universal Laborator System!

    Dear Staigen As I Know, they send digital Data! For modulating Sound, I think 100Khz for carrier frequency is a little low, Isn't it? Shahriar
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