All Activity

This stream auto-updates     

  1. Today
  2. 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.
  3. Yesterday
  4. somebody help me

    You have to give us more information so we will be able to help.
  5. Last week
  6. 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. 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. 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? Any suggestions where and what to buy I want to make a 26 mh choke?
  7. Bidirectional DC/DC converters have been widely applied in many fields such as electric vehicles and battery energy storage systems. This article adopted the pulse-width modulation switch model method to obtain the equivalent circuit model of this converter and constructed a closedloop control system of the converter under different working modes:
  8. why the is off?
  9. somebody help me

    a die circuit ,i test the reset pin in 393 ic
  10. Hi Youkito1991, Nice work!. Thank you for sharing your design and make the PCB available for anyone who wish to use it. Your description is nice and also the support of pictures is very useful. Regards, William
  11. 0-30V Stabilized Power Supply

    Let me know your gmail.
  12. 0-30V Stabilized Power Supply

    Hello liquibyte, Can you provide gerber files for that board revision (7) Thank you
  13. Earlier
  14. 0-30V 0-3A Latest Data

    Hi I also made this project after your example (however i had to etch the boards my self, little bit hard from these gerbers but any way:-)) It worked nice but after a little longer session with a 12v 25w lamp the current control started to oscilate and be unreliable when i was testing. Any ideas about where to start. I am not an expert so thats why I am asking. The only thig i have tried so far is ro replace the tle op amp but same result. Attaching some pictures of my project as well..... And yes i realise that a cooling fan is needed:-) Regards Niklas Ok so now solved:-) Now it works like a charm again and the problem was that due to a tight layout i had a small pice of aluminium on the backside of the board between two thin lines. (it did not burn anything so lucky i guess). Just have to find a good way for the cooling fan.
  15. PCB by JLCPCB

    JLCPCB is the Best and Cheap way to order Your Professional PCBs. I'm ordering PCBs from JLCPCB and they are EXCELLENT QUALITY!! This is the PCB manufacturing company for more than 10 Years. They do offer the colors of the PCBs and the Thickness of the PCBs. And the Crazy thing is they offer 10 PCBs for JUST $2!!! So if you are looking for a low cost but quality PCBs then you can checkout their website by Clicking Here. Amazing Website
  16. Where to buy PCB Designs

    I also use it They have a good price and good quality.
  17. Hello, how are you? sorry my engles, I am using the google translator to write this text. I am new to the design of PCB boards. Currently I use EasyEDA to design my electronic prototypes. Surprising tool to design electronic circuits. The most surprising thing is that it gives you a shopping cart to buy the components and order your printed circuit. The company in china is at I have recently placed several orders, I have received all the material before the delivery date. The package delivered was very well organized and well defined. everything has a very good price and very competitive. I recommend using this service for those who dedicate to carry out an electronic project. It is worth trying, I am very happy with the service and the quality of your projects.
  18. help for driver for led

    Hello friends, I need your help, I need an expert who designs an electronic circuit that acts as a driver for a power LED, the circuit must have an input voltage from 3v to 18v and a 12v and 2.1A output , Help me do this thank you
  19. Circuitmaker included one of the most friendly spice simulators, and I still find it more useful and easier to configure and use than the simulation packages in the high end "professional" packages. Good luck, there are lot of packages at various price points to choose from.
  20. jlcpcb is the best for the price and the quality of the product if your pcb size is not more than 100mmx100mm and max 2 layered they made it only for 2$ in 2 days and shipping takes max 5 days (shipping available to most country) they support via and hole plating diffrerent pcb colors are avaible ( green , red, yellow, blue, white, black) for 2$ prototypes you can only choose green pcb solder mask is made so you dont have to worry about oxidation. you can check the process of your product from the site online and i suggest you to choose DHL for the shipping . some images for three pcbs i ordered:
  21. 0-30 Vdc Stabilized Power Supply

    Thank you, Tintin. Adding another 2k2 resistor in parallel solves the problem. Now the rectified voltage is 40,5 VDC and will not rise.
  22. 0-30 Vdc Stabilized Power Supply

    I, I had the same problem of you. To fix it, make a minimum load with resistor. For me a 25mA load was the minimum to decrease this. See there :
  23. 0-30 Vdc Stabilized Power Supply

    Then i should assume that my 30.5VAC transformer has a number of widings for a 29.5VAC. The widings are at a ratio of 2,44 turns per volt. So i need to remove 2 or 3 turns to get something near the ideal 28AVC.
  24. 0-30 Vdc Stabilized Power Supply

    The peak of 30.5VAC is 30.5V x 1.414= 43.13V. The bridge rectifier has diode voltage drops of 1.4V when there is no load so the positive supply will be 43.13V - 1.4V= 41.73V. If your mains electricity voltage rises then the opamps might be destroyed. I do not know why your voltage measurements are wrong. A 28VAC transformer is about 29VAC with no load. Then its peak is 41.0V and the bridge rectifier reduces it to 39.6V with no load which is fine for the 44V opamps.
  25. 0-30 Vdc Stabilized Power Supply

    Hello. I have a question about the rectifier part of this project. I recently made a transformer and a rectifier board that outputs the GND, 30VDC and -1,4VDC lines. Since the winding was made by hand, the output voltage got a little off. Instead of a 28AC output, i got something around 30,5AC. The problem starts when i connect the transformer to my rectifier board. The positive output gets to 45VDC and begins to slowly rise until it hits 49VDC. The negative line stays at -1,6V. I'm more worried about the positive supply since the OPAMP can only take 44Volts.
  26. Just before creating my next projects tutorial, which will be using a PIR sensor, I thought I might create a separate tutorial explaining the working of a PIR sensor. By doing that I will be able to keep my other tutorial short and to the point. So, without wasting time let’s discuss what is a PIR sensor and how we can use it in our project. Step 1: Basic What is a PIR sensor? PIR or "Passive Infra-Red" sensor is a "Pyroelectric IR Sensor" which generates energy when exposed to heat. Everything emits some low level of radiation, the hotter the object is, the more radiation is emitted. When a human or an animal (with IR radiation wavelength of 9.4µMeter) approaches the sensors range the sensor detects the heat in the form of infrared radiation. The sensor only detects the energy emitted by other objects and don't produce any, that's why the sensor is called a PIR or "Passive Infra-Red" sensor. These sensors are small, cheap, rugged, low-power and very easy to use. Step 2: Hardware For this tutorial we need: 1 x Breadboard 1 x Arduino Nano/UNO (Whatever is handy) 1 x PIR Sensor 1 x LED and a 220 ohm current limiting resistor to test the connectivity Few connecting cables A USB cable to upload the code to the Arduino & General Soldering Equipments Step 3: Architecture As we can see the sensor has two sides: 1. Top or the Sensor Side 2. Bottom or the Components Side The Top consist of a specially designed 'High-Density Polythene' cover called "Fresnel Lens". This lens focuses the infrared rays to the underlying 'Pyroelectric Sensor'. 9.4 µMeter infrared rays can easily pass through the polyethylene cover. The sensors sensitivity range between 6 to 7 meters (20 feet) and the detection angle is 110 degrees x 70 degrees. The actual sensor is inside a sealed metal can. The can basically protects the sensor from noise, temperature and humidity. There is a tiny window made of IR-transmissive material to allow the IR signals to reach the sensor. Behind this window are 'two' balanced PIR sensors. In idle state, both sensors detect the same amount of IR radiation. When a warm body passes by, it first intercepts one of the two sensors, causing a positive differential change between the two halves. And then, when it leaves the sensing area, the reverse happens, and the sensor generates a negative differential change. When the pulse changes or in other words the PIR sensor detects motion, the output pin changes to "digital high" or 3.3V. The bottom bit consists of a bunch of circuitry. Few of them are of our interest. - Most PIR sensors have 3-pins VCC, GND and OUT. VCC and GND are to power the module (Operating voltage: DC 5V to 20V). The OUTPUT pin is the one which communicates with the micro-controller by sending digital pulse high (3.3v) when a motion is detected and digital low (0v) when no motion is detected. The pin-outs may vary between modules so always triple-check the pin-outs. - The BISS0001 or the "Micro Power PIR Motion Detector IC" gets the output from the sensor and after doing some minor processing it produces the digital output. - The module has two potentiometers one to adjust the sensitivity (which is up to 7m) and the other to adjust the time for which the output signal should stay high when an object is detected (it ranges from 0.3s to 5 mins). - There are 3 more pins on this module with a jumper between them to select the trigger modes. > 1st one is called "non-repeatable trigger" - this one goes low as soon as the delay time is over. > 2nd one is called "repeatable trigger" - it stays high as long as the object is in the proximity and will turn off once the object is gone and the delay is over. I will be using this mode for this project. If you want to do a quick test before going ahead with this tutorial please follow the steps below. A testing is also a good idea to test the range and duration of sensing. Step 4: Connecting Without Arduino - Connect the VCC to the +5v rail of the breadboard - Connect the GND to the -ve rail - Connect the LED along with a 220 ohm resistor to the OUT pin of the sensor Now, when the sensor detects a motion, the output pin will go "high" and the LED will light up. Move back and forward to find out the sensing the range. Then to test the duration walk in front of the sensor and then walk away and use a stopwatch to find out how long the LED stayed on. You can adjust the time or sensitivity by adjusting the POTs on the board. Step 5: Connecting With Arduino Now, to do the same with Arduino connect the VCC of the PIR sensor to the 5v pin of Arduino. Then connect the OUTput pin to D13 and GND to the Ground pin of the Arduino. Now, connect the LED along with a 220 ohm resistor to the D2 pin of the Arduino. Thats it, now you just need to upload the code and test if everything works the way it should. You can replace the LED with a Buzzer (to raise an alarm when an object is detected) or a Relay to drive a high voltage circuit. To learn more about relays please have a look at my tutorial Number 4 - "Driving a Relay with an Arduino". Step 6: Code The code is very simple * Start by defining the pin number 2 and 13 as LED pin and PIR pin respectively * Then we need to define the pin modes. LED pin to be the OUTPUT pin and PIR pin to be the INPUT pin * Next we need to read the value of the PIR pin and see if it is HIGH * If the value is HIGH, then turn ON the LED otherwise turn it OFF Step 7: Areas of Application of PIR Sensors PIR sensors can be used to: * Automate Opening and Closing of Doors * Automate All Outdoor Lights * Automate Lights of Basement, Garden or Covered Parking Areas * Automate Lift Lobby or Common Staircases Lights * Detect Presence of Human and Raise an Alarm * Create a Smart Home Automation & Security System, and many more.... Step 8: Demo So, this is my setup for the testing of the PIR sensor. The sensor is hooked up to the breadboard and is sitting on the table. As I am in front of the sensor the LED is on. Now, lets do a quick test. Currently, the sensor is in its idle state. I am going to walk in front of the it to activate the sensor. Tada, the LED just turned on after detecting my presence. The light stays on as long as I am in the sensors proximity. OK, lets walk away and start my stop watch to see if it turns off after 5 seconds. Success, everything worked the way I wanted. 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.
  27. 0-30V Stabilized Power Supply

    Thanks for the reply and the advise. You make good point to switch transformer windings based on output. I didn't consider the current mode.
  28. JLC PCB Review

    I know it . Very good !
  1. Load more activity