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Showing content with the highest reputation since 12/11/2018 in all areas

  1. 1 point

    0-30 volt stailized power supply

    If the transformer is rated at 24VAC/2A then it provides a maximum power of 24V x 2A= 48VA. But if the output is 30V at 2.0A then the load uses 30V x 2A= 60VA plus heating power. The peak of 24VAC is 40V which feeds the bridge rectifier which charges the main filter capacitor to the peak voltage minus the rectifier forward voltage. So then the transformer must produce 40V at 2.0A= 80VA which is much more than the overloaded 48VA. 80VA/24V= 3.33A, not 2A. For a regulated output of 30.0VDC at 3A then I recommended using a transformer rated at 28VAC/4.3A. For an output current of 3A then you must look at how much heat is produced by the single output transistor which is why I recommended using two output transistors to share the heat. Edited with strike-throughs.
  2. 1 point

    Safe Power for electronics

    I’m in the process of a move to an area which I’ve been told has regular power fluctuations and a few power cuts as well. I have been researching how to provide clean and safe power to my electronic components which would include a Denon receiver, 2 Power amps, a Blu-ray player, Projector, gaming console etc. I am contemplating the below options: Option A: Mains to a Voltage Stabilizer to Power Condtioner(Furman) to the electronic components Option B: Mains to an Online UPS(APC) to a Power Condtioner(Furman) to the electronic components Would one of these work? Or is there a better solution to consider?
  3. 1 point
    Holy Hathaway

    555 timer

    The 555 timer is a medium-sized integrated circuit developed by Signetics in 1972 to replace mechanical timers. It is named after the input is designed with three 5kΩ resistors. This circuit later became popular in the world. At present, there are four popular products: two BJTs: 555, 556 (with two 555); two CMOS: 7555, 7556 (containing two 7555). The 555 Timer is a mid-scale integrated device that combines analog and digital functions. It is called 555, which is usually fabricated by bipolar (TTL) process. It is called 7555 by complementary metal oxide (CMOS) process. In addition to single timer, there is corresponding double timer 556/7556. Its power supply voltage range is wide and can operate from 4.5V to 16V, the 7555 can operate from 3 to 18V, and the output drive current is approximately 200mA, so its output is compatible with TTL, CMOS or analog circuit levels. The 555 chip is an extremely versatile chip with up to hundreds of different applications including time-base timing or switching and voltage controlled oscillators and regulators. For those who have been exposed to digital or analog circuits, the 555 chip is definitely a classic. With its low cost and reliable performance, it is widely used in various electrical appliances, including instrumentation, household appliances, electric toys, and automatic control. Its various pin functions are as follows: Pin 1: external power supply negative terminal VSS or ground, under normal grounding. Pin 2: Low trigger terminal TL, this pin voltage is valid when it is less than 1/3 VCC. Pin 3: output OUT. Pin 4: directly clear the terminal RST. When this terminal is connected to a low level, the time base circuit does not work. At this time, regardless of the level of TL and TH, the time base circuit output is “0”, and the terminal should be connected to a high level during normal operation. Pin 5: CO is the control voltage terminal. If the pin is externally connected, the reference voltage of the two internal comparators can be changed. When the pin is not used, the pin should be grounded into a 0.01μF (103) ceramic capacitor to prevent high frequency interference. Pin 6: High trigger terminal TH, this pin is valid when the voltage is greater than 2/3 VCC. Pin 7: discharge end. This terminal is connected to the collector of the discharge tube T and serves as a discharge pin for the capacitor at the time of the timer. Pin 8: external power supply VCC, bipolar time base circuit VCC range is 4.5 -16V, CMOS type time base circuit VCC range is 3-18V, generally 5V.
  4. 1 point

    BMS Charger for 18650

    This is the basic connection of BMS charger circuit. Do you need the scheme for the charger it self maybe?
  5. 1 point

    BMS Charger for 18650

    Need info for scheme bms 12v I -[===]+ -[===]+ -[===]+ l I -[===]+ -[===]+ -[===]+ l I -[===]+ -[===]+ -[===]+ l I. I I. I I. I 12v - 12v +
  6. 1 point

    Rc car

    Perhaps the chip is over heating with to much current draw? Try connecting only two motors to see what happens. For the l298n chip itself: For the IO Peak Output Current (each Channel) – Non Repetitive (t = 100ms) 3.0A –Repetitive (80% on –20% off; ton = 10ms) 2.5A –DC Operation 2.0A TOTAL DC CURRENT UP TO 4 A
  7. 1 point
    The board is made very precisely, it's clean and very pleasant to touch. Markings on the silkscreen layer are very good readable. Soldering does not cause trouble, tin adheres very well to soldering points with a small amount of flux. It is also worth mentioning that the PCB is very robust to desoldering. The company is very solid, although you order 10 pieces, you get at least 1 PCB more for test, prototype, present, etc. When I signed up for an account, I also got a $20 coupon for free. Excellent construction and assembly work done by PCBgogo.No problems encountered, highly recommended.
  8. 1 point
    Perhaps? To big? " This Fujifilm FinePix digital camera has Bluetooth connectivity for wireless media transfer. " https://www.bestbuy.com/site/fujifilm-finepix-xp130-16-4-megapixel-digital-camera-sky-blue/6204739.p?skuId=6204739
  9. 1 point

    Power supply circuit ideas

    If you do not need SMD perhaps "The LT138A/LT338A (LM138/LM338) series of adjustable regulators provide 5A output current over an output voltage range of 1.2V to 32V." The LM338 is about 1$ each on ebay.
  10. 1 point

    LED panel .

    I cannot see which connects to what. Can you provide a schematic?
  11. 1 point

    0-30 Vdc Stabilized Power Supply

    The original circuit should work fine up to 15V at 1A if you replace the old opamps with the newer higher voltage ones. You probably should recalculate the resistors that set the maximum voltage and current outputs. If the Chinese kit uses the transistor that shorts the opamp output when the power is turned off then the resistors that feed the transistor need to be recalculated for the reduced voltage. I have used perforated stripboard for many projects including very complicated ones. The copper strips are cut to length with a drill-bit and become almost half the wiring of a pcb. The parts and a few short jumper wires become the remainder of the wiring. Only one wire is in each hole so changing a part is easy like on a pcb.
  12. 1 point

    0-30 Vdc Stabilized Power Supply

    Did you know that Chinese companies (ebay, Aliexpress, Banggood, Amazon and others) have copied the original defective Greek kit and used the wrong opamps and resistors that burn up? Their kits of the original project are very cheap. They use some Oriental transistors instead of the original ones.
  13. 1 point

    0-30 Vdc Stabilized Power Supply

    The original project used a 24VAC transformer and TL081 opamps that have a maximum allowed supply of 36V. Since the project was not able to produce 30VDC at 3A because the supply voltage was too low, I changed the transformer to 28VAC and changed the opamps to TLE2141 that have a maximum allowed supply of 44VDC. Please post a video of your TLE2141 opamps blowing up if you power them from the 66VDC produced from rectifying the 48VAC from your wrong transformer. Or just parallel the two 24VAC secondaries which produces a rectified 32VDC so that the maximum regulated output from the project will be about 25VDC at 3A. The TLE2141 U2 gets warm, not hot because its output current is fairly low since it drives the driver transistor Q2 that drives the output transistors to 3A.
  14. 1 point

    0-30 Vdc Stabilized Power Supply

    One 2N3055 transistor overheats in the original circuit that used a 24VAC transformer and produces 25VDC at 3A. Therefore I used higher voltage opamps, a 28V 4.2A transformer, a more modern driver transistor Q2 that can be cooled well and two 2N3055 transistors to share the heat on a very large heatsink. Some people added a fan and a smaller heatsink instead of a huge heatsink. If you connect the two 24V windings of your transformer in series and use the centertap as 0V then its output voltage will be 24VAC x 1.414= 34V minus the 1V for the two rectifiers then the supply voltage will be too low because the circuit needs a 28VAC transformer. Your transformer voltage is too high so it cannot be used for this project. Or you could parallel the two 24VAC windings or with the centertap as above then the maximum regulated output voltage will be 25VDC at 3A.
  15. 1 point

    0-30 Vdc Stabilized Power Supply

    The 24VAC transformer has an output voltage too low for this power supply to produce 30VDC at 3A. The regulation will fail and there will be lots of ripple in the output at and above about 25V at 3A. I recommended a 28VAC or 30VAC transformer and higher voltage opamps years ago. For an output up to 5A then the transformer max output current should be 7A or more, the main filter capacitor C1 value should be about 17000uF or more, there should be 3 output transistors each with its own emitter resistor, a larger heatsink for the output transistors and change the value of R7 from 0.47 ohms to 0.27 ohms. I finished making improvements on this project in July, 2014 but others have made more changes.
  16. 1 point

    0-30 Vdc Stabilized Power Supply

    The TIP31 is 83 times slower than the BD139 that I recommend that has almost the same speed as the original 2N2219 that got too hot as Q2. Then the TIP31 will probably cause oscillation.
  17. 1 point

    0-30V Stabilized Power Supply

    Why do you show an LT1038? it is obsolete and is not made anymore. It is impossible for it to dissipate 32V x 10A= 320W. Its datasheet shows that with a huge heatsink with fan or with liquid nitrogen for cooling it can dissipate only 120W. Its control circuit gives 10A only when its input to output is a few volts and cuts the max current to 2.5A when the input to output is 30V.
  18. 1 point

    BGA rework Process?

    Hey, I also found a training institute and an article about BGA Rework Process. Follow the given link below to get a clear understanding of reworking BGA process: http://www.solder.net/services/bga-rework-services/
  19. 1 point

    Power supply

    A power supply is an electronic device which supplies electric energy to an electrical load. Can anyone tell me what is the minimum power required 1 ton AC.
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