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  2. Hello, We wish to see if our offline Switch Mode LED lights are immune to noise. Therefore, we will make a special “noise producer” as in the attached. It is simply an LLC converter with one of its switching nodes dragged out of the enclosure for 30 metres. This 30 metres is loosely twisted (it’s also insulated wire). We will drape this 30 metres of “noisy wire” over our products as they are working –to see if it makes them go wrong. Do you think any of the products will go wrong when the “noisy wire” is draped over them? Might any operating electronics products be disturbed by being brought near to such a wire? The waveform of the square wave of the wire is also shown. It is a square wave with 7ns rise time. LTspice simulation of "noise producer" attached also. By the way, the LLC converter ('noise producer') shown feeds off the output of a fully isolated full bridge converter, which itself feeds off the output of a 240VAC mains PFC stage
  3. Hello, Recently, I've been playing with flyback SMPS topology for fun but also to make a reference design for eventual future use in commercial products. Specifically, what I am experimenting with is a capacitor charger (those things for which one usually uses a LT3750 or LT3751) and I want to charge the biggest possible cap in the shortest possible time. Power and efficiency. One thing I learnt is that when you need higher output voltage, and you don't have a suitable transformer, ie. when you need high duty cycles, you start finding that leakage inductance and other problems play a bigger role. Consider also that I pretend to do all the experiments in software, on a EF PIC32, and when you use a transformer with 10uH primary inductance, you are very short in time, especially during the discharge phase of a high duty cycle when you want to do things like zero-voltage (valley) switching. Anyhow, experimenting brought me towards the implementation of a two-switch topology of flyback SMPS, something I had overlooked before. I now understand the beauty and usefulness of this topology. This way, the transil/snubber is gone, the MOSFETs can be much lower voltage, and I have a chance (not verified yet) to measure discharge current with much higher precision and ease (while measuring discharge current is not necessary, I think I can do some interesting things if I can measure it). To experiment (but always with eventual, future, production design in mind) with it I need a low side and high side driver for the 2 MOSFETs, which do turn ON and OFF simultaneously albeit on two different "rails", and I want to drive them directly via a MPU pin, ie. logic level (for my ease and for containing noise even in imperfect PCB), but I can't find any suitable IC for this task. Is there one, or can any of you suggest some smart/clever solutions to drive with as few components as possible (also to reduce board space and interference as I'll be switching tens of Amperes, maybe in continuous mode, not even discontinuos) both MOSFETs simultaneously, considering the ~12V difference between them? One a side note: I noticed that the "primary" part of two-switch flyback and two-switch forward converters are identical, the only difference is on the secondary side. What are the benefits of implementing a type of secondary (flyback) or the other (forward)? Thank you.
  4. 0-30V Stabilized Power Supply

    Two transistors gives double the area used to transfer the heat.
  5. 0-30V Stabilized Power Supply

    Maybe you use the power supply to test a 3A forward biased diode. Then the output transistor gets very hot.
  6. Has this ever happened to you? You come back from a romantic dinner date and when you open the shutter door of your garage you realize that you left the garage light ON. You spent few hours outside with your partner to impress her and all the time this light bulb was on. You immediately turn around and look at her face to see a silent anger on her face. Alright, enough of that. So, in this tutorial, I am going to turn on and off the garage light using a PIR sensor. When the sensor detects a moving object, it turns on the light bulb and when the moving object is gone, it turns it off. Lastly, I am going to make sure that light bulb only turn on during the night time (when its dark). Step 1: Logic In this project, I will be using a PIR sensor along with an LDR to turn on or off a light bulb using a Relay. The things I need to consider before designing the circuit are: - The bulb should only turn on when the room is dark and when a motion is detected. - The bulb should turn off after 30 seconds of the object leaving the sensors proximity. - Most important, we need to place the LDR in a place where it doesn't turn off the bulb as soon as it lights up. Step 2: Hardware For this tutorial we need: A General Purpose PCB 2 x HC-SR501 PIR Sensor 2 x 1N4148 Small Signal Fast Switching Diodes 1 x 1N4007 High Voltage, High Current Rated Diode to protect the micro-controller from voltage spikes 1 x LDR 1 x 10K Trimmer Potentiometer 2 x 470 Ohms Resistor 1 x 10K Resistor 1 x 1K Resistor 1 x 2N3906 General Purpose PNP Transistor 1 x 2N2222 General Purpose NPN Transistor 1 x 5V Relay 1 x LED to display the status 5 x Terminal Blocks 1 x 220V to 5V Buck Step Down Module Few Connecting Cables And General Soldering Equipments Step 3: Assembly Lets first connect the LDR and setup the light detection bit. As we all know we need to setup a voltage divider to use the LDR in a circuit, so, I am adding this 10K POT and 470ohms resistor to setup the voltage divider bit. By adjusting the resistance of the POT we can adjust the intensity of sunlight at which this circuit will operate. Now, lets install the PIR sensor. Connect the VCC to +5v and GND to ground. Then connect the 1N4148 diode to the OUT of the sensor. In this circuit, I am installing just one sensor however in the actual project I have used 2 sensors to capture a bit more than 180 degrees. So, to avoid the sensors from back-feeding each other we need to install a diode to the OUT pin of each sensor. If you want to capture motion at 360 degrees you may need 3 to 4 sensor and diode pair to achieve that. Now that we have the PIR sensor and the LDR in place we need to add the 'AND' functionality. To achieve this I am adding a general purpose PNP transistor. When a motion is detected 'and' when the sunlight is at a certain intensity (adjusted by the POT) current flows out of the transistor. Next, we need to amplify the current received from the collector of the PNP transistor and turn on and off the LED indicator and the Relay. A general purpose NPN transistor is used to achieve this. That's it all done. Step 4: What Have I Have Made So, this is what I have made. On my board components are pretty much soldered everywhere, but you may like to have them nicely installed to give it a bit more cleaner look. OK, so lets check out how this works. Step 5: Demo Alright, I have placed the board on this table to do a quick test. I haven't hooked up a light bulb to the circuit yet. However, the LED indicator should serve the purpose of this demonstration. So, now I am going to turn off the light and make the room dark. Let's see if the sensor picks up motion and lights up the LED. Tada, it works. Now, lets turn on the light of the room and see if the LED indicator turns off or not. Yessss, that works. OK, finally just want to make sure that the light bulb turns off after 30 seconds of me moving out of the sensors proximity. Boom, and that concludes the project. I can now install it on the ceiling and make my partner happy. Instead of having 2 to 3 PIR sensors you can use one and install it at the corner of the wall. However, that will require a fair bit of wiring either inside the roof or on the ceiling, which will be way more expensive and tedious than installing 3 sensors an d putting the device in the middle of the room. You can also swap the Arduino with a NodeMCU board and do a remote data logging to log the time when the sensor detected motion or when the light went on to record when people entered your garage and how long they stayed in there. Step 6: Areas of Applications of PIR Sensors This setup can be used to: * Automate All Outdoor Lights * Automate Lights of Basement, Garden or Covered Parking Areas * Automate Lift Lobby or Common Staircases Lights * Automate bedside or night lamp * Create a Smart Home Automation & Security System and more.. Step 7: Thanks Thanks again for watching this video! I hope it helps you. If you want to support me, you can subscribe to my channel and watch my other videos. Thanks, ca again in my next video.
  7. 0-30V Stabilized Power Supply

    Whether you use one, or multiple transistors, the total power of 114W must be cooled somehow. Unless separate heatsinks are used for each transistor, then the problem still exists. Remember, though, that it is 114W if the outputs are shorted together - that's pretty unusual, so the normal running mode should be a lot cooler anyway.
  8. 0-30V Stabilized Power Supply

    Good luck trying to cool 114W so that the case is not too hot.
  9. I'm intending to use it in low current projects like oscillators, arduino projects - these sort of things - to learn electronic but also I'd love to drive fly-backs for juicier arks (which I've already done with my ATX power supply, of course with the standard measurements and personal protection to avoid electric shock), and olds vacuum tubes. I could instead buy one here. But, for a reasonable price, I could only find Yaxun brand, which I don't take a lot of faith (the good one are like 3 or 4 times the price of these Chinese). I do not think I'll draw too much current from it often... So, this point can be left aside, but, yeah, you're right: by mine calculations, something about 7W per transistor will be lost upon high load. The first question is crucial for my project! Thank you for your reply!
  10. 0-30V Stabilized Power Supply

    Yes, I did realise the mis-type, and agreed that it wasn't right to operate so close to the maximum. Do you have any comments regarding the use of the 150W rated transistor instead? After all, we are talking about a margin of around 30%...
  11. 0-30V Stabilized Power Supply

    I'm a tough guy why I need a toy car for 3 Amps, for a tough guy you need a cool device, here I made for myself a cool device from 0-40 amps
  12. Best tape for conformal coating process?

    Please suggest, if anybody have any idea?
  13. 0-30V Stabilized Power Supply

    I wrongly typed 114A instead of 114W. A single 2N3055 will be at its maximum allowed chip temperature of 200 degrees C when it dissipates 115W and its case is cooled to no more than 25 degrees C with liquid nitrogen or something. A heatsink also gets hot even when it is huge and has a fan blowing on it. I never operate a transistor anywhere near its maximum temperature, voltage or current. Then it is reliable.
  14. About LongTechnical » In this video i had show you Portable Voltmeter Ammeter Wattmeter with Rechargeable Battery Insite All of thing we need in there. Please check on description and do step by step you will get Portable Voltmeter Ammeter Wattmeter The firts we need to make PCB. I use eagle software for design shematic and PCB. After that i order the PCB by upload gerber file to JLCPCB.COM and after 2 day i reieved 10PCB high quality with only 2$. You can try like my by upload gerber file to JLCPCB.COM for get PCB online. Or you can make PCB by yourselft by download the PDF file at end of topic. look at some picture from my project, and check more video at my youtube channel LCD metter.pdf LCD metter2.pdf
  15. Your project is good but when we use with big load ( big current) we waste a lot of power for heat from transistor.
  16. Every lab bench power supply that I am familiar with outputs only DC. The best power supply really depends on the application. What type of work or projects are you intending to use the supply for? I am most familiar with the Tek & Agilent supplies with 0–5v adjustable outputs and a 0–25v output. For hobbyist use, much more economical options can be found that would meet those needs.
  17. 0-30V Stabilized Power Supply

    Еу firmware : 30 volts 10 ampere 30 volts 20 now 50 volts 10 ampere 50 volts 20 now 100 volts 10 ampere 100 volt 20 ampere Апреле*))) Амреге
  18. 0-30V Stabilized Power Supply

    My 5 MJ11032 ,no 2n3035 on my scheme is 5 pieces TRANSISTOR MJ11032, at the entrance two powerful impulse transformer of 40 volts 25 ampere, at the output of the laboratory power supply 32 volts 50 ampere
  19. 0-30V Stabilized Power Supply

    Agreed - the 2N3055 is rated at 115W maximum, and as the voltage drop also depends on what the ammeter internal resistance will be, it shouldn't be running so close to its limit. The hFE parameter of the 2N3055 is very loosely defined (as is the case with most BJTs), so one of the transistors could be carrying in excess of 2A, and will run quite a bit hotter than the other, but not a big problem. Of course, the alternative is to use a single transistor rated with a higher wattage! I wondered about the 2N3771, but couldn't find a spice model for that. I did find a spice model for the FJL4315, which is rated at 230V, 15A and 150W, and has an hFE of 60, so pretty much a drop-in replacement for the 2N3055, and would handle everything the supply could throw at it.
  20. Hi there. I need a good bench power supply, which i want to build myself, for my hobby lab. The thing is, i have been thinking about LM-317 as my linear voltage regulator (and because here where i live i don't have no access to better ones). The design must have these features: a)Current control from few mA to 5A b)Voltage control from 0V to 30V. For this purpose I've built this schematic, which i attached here. Please, tell me what you think about this project or if does work or does not, for i am a beginner in these things. R8 is just a dummy load. The things i need help: 1) How can i add a minimum load (10 mA as by LM-317 datasheet) to keep the power supply operating in different potentials? 2) I need a replacement for 2n3822, i can't find it in my country too. 3) Can I run it from a fixed switched power supply (way more cheaper than buying a transformer here)? 4) In the future, I'm thinking about adding digital control with PWM to this circuit with Arduino or something like that. Do you think this is feasible? Thanks in advance and sorry for my English. PS: i have already looked here in this forum about the 0-30v power supply with op amps, but i really like the LM-317 concept, although i will build this last one if my project fails.
  21. 0-30V Stabilized Power Supply

    Your idea to use only one 2N3055 output transistor will have it burning hot (38V x 3A= 114A!) if the current is set to 3A and the output is shorted or has a very low voltage. Two output transistors share the heat. Their emitter resistors match them pretty well. Two output transistors at b1.5A each will have a higher hFE than only one transistor at 3A then the driver transistor does not need to supply a higher current and it also stays cooler.
  22. Where to buy PCB Designs

    You can buy PCB designs from Optimatech: There is a knowledge section where you can take help from.
  23. 0-30V Stabilized Power Supply

    Hi All, I saw this post by Liquibyte, and decided to take up the challenge of offering suggestions. First, I'd like to say that I've enjoyed looking through this thread, and am very impressed with the work that has been done here by Liquibyte, Audioguru and others. I have made some alterations to this new design, BUT I've not yet constructed it. However, there are a number of things that I discovered when simulating with LTspice. In the attached, I've made a number of alterations - rather than using a diode to ensure that the voltage reference is pulled down only when U1 is active, I've used a transistor. The reason is that if the output were short circuited, then the inverting input of U3 would be zero, so U3 can never get the inverting and non-inverting outputs equal. Hence the current is only limited by the output transistor drive capabilities since the minimum of the non-inverting input is the diode voltage drop plus the minimum output of U1. Instead, I've used a transistor which can pull the non-inverting input of U3 very close to 0V (VIN-), which will be less than VOUT-, so the output of U3 will drop, and cut the voltage at VOUT+. The second major difference is to remove the unnecessary output transistor Q4. A single 2N3055 can drive up to 15A, so doubling up is not necessary. (In fact, unless the transistors are well matched, it may have no effect whatsoever as at these "low" currents one transistor would carry the bulk of current if the matching were not perfect). I was puzzled by the need for R13 until I realised that this is supposed to be part of circuitry to limit the current output of Q3. I'm assuming that at some point in the past, the diodes that make this work were dropped - perhaps to keep the voltage up under high drive conditions? In the redesign I've added three diodes from VOUT+ to the base of Q2. If U3 tries to drive too much current through Q3, then the excess drive current will be routed through the diode chain, effectively limiting the drive current into Q3. If the voltage is dipping under heavy load currents (less than the limit of 3A), then the output resistor can be reduced in size. However, the consequence is that the maximum output current spike will be higher. One other final structural modification is to separate the voltage sense and current sense parts of the circuit to allow the common Voltage/Ammeter module to be installed. As I've not built the circuit yet, I don't know what the internal resistance of the ammeter is, so I've put a nominal 0.15Ohm resistor in there. Obviously this should be changed to whatever is appropriate. With a little reorganisation in the drawing, which includes some test circuits: a 555 astable which has power spikes as it is not decoupled, a resistor that is suddenly shorted out at 0.5s, and a resistor that varies between an almost infinite resistance to zero in a way that should make the current rise linearly up to 0.5s, and then the voltage drop linearly. Also, I've included a period after 1s when the supply is switched off. When I did this, I found it necessary to modify the power supply to U1 to ensure that it continued to limit current, otherwise I ended up with a large current spike after the power source had been removed. I've also added a few notes discussing things I've discovered when changing things around. I'm offering this revised (but note UNTESTED) design to the forum. Just one note, I've seen pictures of some builds, and am slightly concerned that the casing of 2N3055 is not covered by everyone. The case of the 2N3055 is the collector, which will be at around 38V. If someone connects VOUT- to earth, then the full 38V will be present on the case, with whatever current the transformer can supply. Under the right (i.e. wrong!) conditions, this could be fatal. Please make sure the case is covered! If anyone builds this, then I'd be really interested to hear how they get on. If you do, please try to understand how the design works first - working with high currents with an untested circuit is not something that should be taken on by those not very familiar with circuit design/construction. My plan is to build a lower current/voltage version of the supply (I really don't need 30V, nor 3A), but finding the time to do this is my biggest problem... Dave.
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  25. somebody help me

    You have to give us more information so we will be able to help.
  26. I bought some Green 10mm x 25mm Ferrite Toroids from China. 1 Green toroid with 11 turns of wire on makes a .5 mh choke. more: dự án sun láng hạ 2 Green toroids taped together with 11 turns of wire makes a 1 mh choke. 4 Green toroides taped together with 11 turns of wire makes 1.8 mh choke. 1 TV toroid white snap together plastic case with 37 turns of wire same physically size as 1 Green toroids makes a 8 mh choke. 2 black natural color toroids taped together 4 times larger than 1 Green toroids with 11 turns of wire mades a .2 mh. Larger is NOT better. more: tasco xuân phương I am looking for toroids in several places and not finding much. I bought toroids from Jameco in the past but they no longer have toroids listed. Ebay has some but there is NO date about the toroids. I checked several of the parts companies listed on this forum not finding many toroids. One place called West Florida Components has a small .8 inch toroid that says it his high flux. I'm not finding pre made chokes either. Will higher flux make a higher mh choke? more: dự án sun láng hạ Any suggestions where and what to buy I want to make a 26 mh choke?
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