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Everything posted by Shahriar

  1. ThanX all Dear Audioguru Obviously, NPN is a complimentary of PNP. But when it is mentioned that TIP41 is Complementary of TOP42, I think it means to using these two together is better. But what Parameters makes TIP42 suitable to use it with TIP41? ThanX Shahriar
  2. Hi In Transistor datasheet there is alays a word “Complementary”. For example TIP42 is TIP41 Complement. What does this mean? ThanX Shahriar
  3. Dear ECET0purdue For example casset tape player! In a topic, I can remember Audioguru had said that it was invented by PHILIPS, and during those days he was working at PHILIPS. anyway, I do n't think it is always improvement. When I take look at TV Chassis, One Model is Completely differs with another on. and while both are from a same Company. ThanX Shahriar
  4. Hi Maybe this topic is not related to this forum; Take it easy, because in this case, MP will move the topic. ;D ;D Today, when I was looking at my Camcorder, I thought to myself How Big Company engineers Build such complicated Devices. when a big company decides to design a new device, i.e. a camcorder, How do they select the Team Members and how do they organize them. obviousley, a Camcorder Electronics is not built just by One Person. and the teams needs New and Inventory Circuits. the Mechanic mechanism need Mechanic Engineers and so on. How do they beging and finish it. ThanX Shahriar
  5. Dear Alun Thanx Very much for your help and also thanx to audioguru. ( I read those links), that's great Help. In the following circuits, Can you Write some Equations Between Vgate, Vdrain, Vsourse. to determine How much Vi can change? Specialy in P-chanel Mosfet ThanX shahriar
  6. Hi I want to add a linear PS to a SMPS to improve regulation and vary the output voltage between 0-30V. The Vi in the schematic comes from SMPS .In worst condition it has 250mV ripple. To reduce power dissipation in trasistor I plan to change Vi when I want to change Vo, But I always have to keep (Vi), 3.5V higher than (Vo) to keep LM317 working proplerly. {the trasistor turns on when LM317 darws 20mA. the input voltage of LM317 must be 2.5V higher than its output. If Veb=1V then (Vi-Vo = 2.5V + 1V =3.5V) } when I draw 10A, My SMPS should produce 35W more (10A * 3.5V) and dissipate this power in Linear PS. I want to know how can I do a trick which enables me to reduce this Differential Voltage(3.5V) Lower. i.e. down to 1V which components can I use instead pf LM317.
  7. Dear Staigen [shadow=red,left][/shadow] If you mean the Component side of PCB, In the Antenna Board, I should say nothing I think you misunderstood my meaning, There is nothing on the Component side because it is a single layer board ;D ThanX Shahriar
  8. Dear Staigen If you mean the Component side of PCB, In the Antenna Board, I should say nothing, but in PC motherboard, I should say I don't know because the Motherboard as you know is a 4 or more layer PCB. Dear Audioguru Maybe It is as you said. ???
  9. Hi I want ot add a current limit to my SMPS. at the output, I have an inductor that creates a LC filter to reduce ripple. Can I measure the voltage drop across this inductor instead of putting a low Value resistor? Please do not care about little voltage drop across that inductor because of low resistance! I will amplfy it if needed. What problem should I encounter? My SMPS is going to be a variable output. ThanX in advance Shahriar
  10. Hi Today when I was looking at my TV Antenna mixer PCB, I saw that some of the tracks have been made in a shape like Two Comb. you can see such shapes in PC Motherboard's Tracks too. What I guess is that they want the two tracks have a same condition like Twisted Wires to remove the Common Mode Interference. Am I right? Here's the picture ThanX Shahriar
  11. Hi Audioguru explained the circuit perfectly. In Communication circuit this is Called AGC(automatic Gain control). the best example of this circuit is in TV Tuners. when a TV receives high power, the AGC amplifies the signal a little and when received power is LOW the AGC Increases the Amplifier Gain. In the main circuit C3 and D1 creat the Clamper circuit which shifts up all negative signal above zero. Clamper are very useful circuits. But Does anybody know how is it possible to design a DC controlled Amplifier with OpAmps? ThanX Shahriar
  12. 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 didn't see any distance. the points which I have marked red and written "there is no space here" is filled with Glue. Do you know where this GAP is? ThanX in advance Sh.Farmanesh
  13. 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 SONY one that can copy both sides of a tape into 3 tapes at the same time and in just 3 Minutes. ThanX in advance Shahriar
  14. Dear Alun I know what tnk2k means, but obviously when power is disconnected and the relay or transistor was disconnected, he wants to turn on or off a siren or any indicator? then how you provide power for that circuit. shahriar
  15. Dear tnk2k When there is no power, The relay can not do anything. 8) Shahriar
  16. 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, ... ThanX a million Shahriar LM317B.pdf
  17. 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
  18. Dear Audioguru ThanX very Much for your Always Complete and Patient Answers... Shahriar
  19. Dear Audioguru You said each side of a tape is devided into 2 Track, One track for Left channel and one track for Right Channel; Then What happens when you put a tape which is recorded with a Stereo Recoder in a Mono Tape(those Simple Ones); Does the Head of these players read just one track; If so, Everythings go wrong ???
  20. Hi Does anybody know how the stereo sound is recorded on a tape? ThanX in advance Shahriar
  21. Dear walid It is a little bit confusing. when there is no Mains power your cicuit will go off. maybe you use a battery, when there is power, your citcuit wil use the power from 12V rail, and also charges the battery. and when ther is no 220V, your circuit will use the Battery power. HTH -Shahriar
  22. Dear ANTE Thank you very much. I had searched the web a whole day, but didn't see the thing you posted? ??? It is very similar to this document I have attached. I have a question In this document: how much voltage changes can we achieve at the output by varying the voltage divider at the TL494 Err Amplifier Input. (Suppose that the Over protection circuit is disabled and the secondary Windings have been changed to proper number) ThanX Shahriar AN983-D.PDF
  23. Salam The best thing you can do is to use a MCU (i.e AVR or PIC) then Measure the voltage across a small resistor via the MCU ADC. then Send it to PC. if the dropped voltage across the res is not big enough, you can amplify it before process. Take a look at this schematic. the resistor is just a piece of Wire. HTH - Shahriar
  24. 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 Some 900W, 1.2 to 30V output smps that can give 30A@30V or 60A@15V on the web. So there is a solution!!! I don't know which topology they have used or which Controller! There are some adjustable Buck Controllers but none of them are Off-line. So I have to use a big transformer.(Not Good) Do you know any way out how to convert usual SMPS to a Variable One? The attached file is a TEA1507 75W Application used for monitors ThanX in advance Shahriar Tea1507Design02.pdf
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