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  1. Shahriar

    460V DC to 400V DC How?

    By the way, your transistors will get too much Hot because of 70W Power dissipation. you should use fan and some more Transistor in parralell and some resistors for current sharing. I hope you understand what I mean!!! HTH - Shahriar
  2. Shahriar

    460V DC to 400V DC How?

    Dear boombar I am not completelty sure but you can do it with those normal Regulator circuits. if you need a good regulation, maybe connecting some zeners in series and a suitable transistor with Vce >= 100V with high enough hfe. if you don't need 400V fix, then you can use two 30V zeners...
  3. Shahriar

    Low drop out voltage regulator with TL431 Problem!

    ThanX all for your replies and your Pictures. At last I made this circuit working. I was sure about my circuit wirings and I was really disgusted. Do you know How I solved it. Look at the picture below: I don’t know much about Zero and Poles in Feedback circuits. But I think this cap will do...
  4. Shahriar

    Low drop out voltage regulator with TL431 Problem!

    Dear Staigen I put Different resistors there to ensure 2N4403 gets off. when I put a low resistor(2.2K even 330ohm) the output goes to 3.8V when I put a bigger resistor the output goes higher 4.8 But in both cases, the output changes when I change the Vi ThanX Shahriar
  5. Shahriar

    Low drop out voltage regulator with TL431 Problem!

    Hi I want to build a Low Drop out voltage regulator(LDO) I tried the schematic Below but the output Changes when I change the input voltage. I wrote the voltages I measured at Vi=8V. I put that 8.2K and 2.2K to create a voltage devider at the base of NPN tarnsistor because the lowest voltage i...
  6. Shahriar

    Help with IR motion sensor

    You can Also creat a latch with D-Filp Flops. 7475. (Check it!) Anyway, there is a project in the Project section of this site. Its name is Park-Aid. Take a look. It will anserw to some of your questions. HTH - Shahriar
  7. Shahriar

    Current Limiting Indication

    Dear MrHeckles One way to do this is to creat an average  DC Voltage on the Vi+ of the Op-Amp. Beacuse there are lots of unwanted Spikes there. These method is used by New SMPS Controllers and Is called Average Current Control Topology. Anyway, without this, it is possible, but you should add...
  8. Shahriar

    Wireless intercom

    Dear wood_workur As your writing implies, you want to sell these devices to customers. On thing that you should remeber is that simple transmitters Frequency will change by Tempreture, and even after a month or a year. So if you want to get rid of customers calls, you should use a PLL based...
  9. Shahriar

    7 segment displays

    Dear stevedabear As Ldanielrosa Said you'd better build one for yourself. About the file ANte Attached, I should say I couldn't download it because it is too big for me to download it. (I have a dial up connection) I have attached The thing you want. with all explanations. U can Download any...
  10. Shahriar

    a Constant Power consumption design

    Hi I have a SMPS that its output varies from 4V up to 32V. As you know at the output of most SMPS there must be a Load to Dissipate some power. For my SMPS, it should be at least 2-3W Because this SMPS is to be used as a Laboratory Supply, I have to put a load at the output. I can not use a...
  11. Shahriar

    What does Complementary Means?

    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
  12. Shahriar

    What does Complementary Means?

    Hi In Transistor datasheet there is alays a word “Complementary”. For example TIP42 is TIP41 Complement. What does this mean? ThanX Shahriar
  13. Shahriar

    Design Steps in Big Companies!

    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...
  14. Shahriar

    Design Steps in Big Companies!

    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...
  15. Shahriar

    Variable SMPS + Variable Linear PS!

    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
  16. Shahriar

    Variable SMPS + Variable Linear PS!

    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...
  17. Shahriar

    Tracks Shape in RF PCBs are like two comb!

    Dear Staigen 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
  18. Shahriar

    Tracks Shape in RF PCBs are like two comb!

    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.  ???
  19. Shahriar

    the voltage drop across an Inductor instead of a Res. for current adjust.

    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...
  20. Shahriar

    Tracks Shape in RF PCBs are like two comb!

    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...
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