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  1. Shahriar

    Where is the GAP in SMPS transformer

    Hi I am designing a 150W Flyback SMPS. I have read some articles. in Flyback transformer calculatoin, there is a parameter ( Lg ) that indicates the GAP and equals to "i.e.  0.0252cm = 9.917 mInches". but I don't know where is the gap on a transformer? When I take a look at a TV Transformer, I...
  2. Shahriar

    Casset tape Distributor!

    Hi I want ot build a device which can copy a casset tape to 5 or more tape at the same time with high speed. what is the best thing to do? If I increase the speed of the master tape and slave tapes with each other, then would it be Okay. How much can I increase the Motor Speeds? there are a...
  3. Shahriar

    Regulator Datasheet Parameters meaning!

    Hi The datasheet I have attached belongs to LM317. I Want to know how much ripple do we  have for a Specific Output Voltage and current.  ??? I would appreciate it If you could help me through an article to understand the Parameters Meaning. i.e. Ripple Rejection Ratio, Long-Term Stability, ...
  4. Shahriar

    Look at this link for different and small SMPS specially Chargers;

    Maybe building an small and light SMPS for powering your devices (specially those small ones) is much more enjoyable than a usual transformer and diode bridge + .... http://www.powerint.com/appcircuits.htm#der75 there are other things too HTH - Shahriar
  5. Shahriar

    HOW stereo Sound is recorded on a tape?

    Hi Does anybody know how the stereo sound is recorded on a tape? ThanX in advance Shahriar
  6. Shahriar

    Once Again, but this time adjustable OFF-LINE SMPS

    Hi I want to build a 150 Watt Off-line SMPS using TEA1507 Controller. It seems that the output voltage just depends on the transformer windings turns ratio, in Flyback, Pushpull, Half-bridge Topologies. So there is no way out to build a High power variable Switching regulator. But I have seen...
  7. Shahriar

    Does anybody know IC for Amper meter?

    Hi I want to build a Digital Ampermetre upto 5A. Does anybody know an IC for this purpose. ThanX in advance Shahriar
  8. Shahriar

    How does OptoIsolator Compensate circuit Work?

    Hi If you take a look at TV or Monitor power supplies, you see a circuit Like the one I have marked red in the picture. In the SMPS guide which I downloaded from SMPS Disscussion of this forum, there was the explanation I have write at the bottom of the picture. Can you explain how that circuit...
  9. Shahriar

    What are those Black lines, when you look at Monitor through Camera?

    Hi When I Look at my monitor through my Mobile Camera I see black lines going up. As I go far from monitor then the black lines will go to disappear. the same thing happens when I record films from TV with my Camcorder. which is the reason? 1- Because the vertical scan frequency of Camera...
  10. Shahriar

    FBAS to RGB Converter

    Hi I have a small Camera that its Output is a RCA Audio/Video Jack. I Plan to design a circuit which can detect: 1- RGB Signals 2- Horizantal Sync Pulses 3- Vertical Sync Pulses. I know how to detect Horizantal and vertical synce pulses. but detecting RGB signals is a little bit confusing...
  11. Shahriar

    What is the difference between FBAS signal and CVBS!

    Hi I am confused between these two signals: FBAS or CVBS. when I take a look in TV schematics I saw them very similar to each other but in a schematic it is written FBAS and in the other one is written CVBS. Can you tell me the difference? 2- What is the frequecy of these two signals. I think...
  12. Shahriar

    Does Anybody know a good Robot Mechanic?

    Hi There is a robotic contest in my university and I want to build a robot with high reliability. But Robot Mechanics has been always Dusgusting to me. The robot should have high Speed, high Power and As Small as possible There is no limit for Power supply because we are NOT going to power it...
  13. Shahriar

    How Microwave Oven Work?

    Hi Does anybody know how microwave ovens work? How do they get things so much hot during seconds? ThanX in advance Shahriar
  14. Shahriar

    The is a VIZZ in the output Sound!!!

    Hi I have build an square wave oscillator with LM324(which is a quad opAmp). I have connected the output to a TIP122(power Transistor) and drive a piezo to creat a beep sound. but the interesting problem: There is a VIZZ in the output sound. when I touch the Vcc or GND or some other points of...
  15. Shahriar

    What is the diffrence between24Cxx and 24Xxx EEPROMs?

    Hi When I found a EEPROM IC which do not work in a TV, I write new data (which I have read before from a working TV with same model)and it always work fine! But in some TV, the memory is IC is 24Wxx instead of 24Cxx fasmily. the when I try to read from them I usally receive bulshit and when I...
  16. Shahriar

    Telephone Billing machine!!!

    Hi to everybody I plan to build a device that many of you may have thought about it before. (or may have heard about it ) The project is to be connected to telephone line. then when somebody hangs up the phone, he is not able to dial a number till he dial a specified number (i.e. 1111 for...
  17. Shahriar

    Any document for RF amplifier designing!!!

    Hi Does anybody have a tutorial for designing RF amplifiers? for example how to calculate L2 or L3 in "4 Watt FM Transmitter " in project section. or where th Base-Emitter voltage of T2 or T3 comes from to turn on the Transitor? ThanX in advance Shahriar
  18. Shahriar

    Do we lose power, If we select a longer Antenna?

    Hi It is said that a very simple calculation for antennas length, is 1/4 * wavelength. my question is: if we select a longer antenna, do we have lose output power? The anttena I mean is for transmitter. ThanX in advance Shahriar
  19. Shahriar

    How To Find Similar transistors!!!

    Hi I spend most of my time repairing TVs. Sometimes I need a trasistor but I can not find it. so I have to buy similar trasistors. My related Books are very old and small so do not have many of transitors. and the new ones are very Expensive. How can I find similar trasistors in Internet...
  20. Shahriar

    How to calculate the crystal Value in Oscillators?

    Hi In many crystal Tx oscillators, I always see that if the oscillator frequency is for example 98Mhz, the crystal value is sth around 12MHz.(a little bit more or less). I have heard sth. like second or third harmonic but do not know anything exact. My questions are: 1- how to calculate the...
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