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  2. Hello. I am Alexander Bondarenko, the author of a book "Mathematical modeling of a pyroelectric detector". As the pyroelectric detector being an electronic component and this forum is more related to theory articles, I decided to upload the book here. Further, I developed a simulator for the detector provided with different settings. You can see the videos here Is there anyone who is interested in advanced understanding of the thermal-to-electrical model for a pyroelectric detector? Thank you. P.S. I am on linkedin https://www.linkedin.com/in/pyrodetector/ Abstract The book offers a step-by-step guide to mathematical modeling of the thermalto- electrical model of a pyroelectric detector. It contains the solutions to ten problems. The first eight problems are related to processes running in the body of the sensitive element from heating or cooling to generating electrical charges in response. The last two problems examine the transformation of input electrical charges to output voltage when the sensitive element is connected to high-megohm electronics. Every solution starts with the equation for the law of conservation of energy and ends with that of the transient response. In order to make reading easier, the author provides almost every equation with corresponding units of measurement which are extremely useful not only for beginners, but also for advanced readers. The book can be recommended to amateurs, undergraduate and graduate students, teachers, engineers, who want to develop advanced knowledge better concerning to the thermal-to-electrical model of pyroelectric detectors. Mathematical Modeling of a Pyroelectric Detector Release.pdf
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  5. 0-30V Stabilized Power Supply

    Great, we are on to something! If R10 in liquibytes schematic is shorted, this would happen. Can you measure it's resistance? R10 is the 1k resistor which sets the 5mA current for the reference zener.
  6. 0-30V Stabilized Power Supply

    The middle opamp in Liquibyte's schematic is the 11.2V reference because it uses a 5.6V zener diode and it has a gain of 2 times. The voltage setting pot R27 is simply a voltage divider that feeds 0V to 11.2V to the non-inverting input pin 3 on the opamp on the right side. The gain of this opamp is 1+ (56k/28.8k)= 2.9444 times so that the maximum output of the circuit is 11.2v x 2.9444= 30.0V. Your middle opamp is messed up since its output voltage is too low.
  7. 0-30V Stabilized Power Supply

    Unloaded or loaded with a minimal load (a 1k resistor and a led) same thing. Voltage drop is about 180 mV, and I don't think it's the current limiting, the current limiting led doesn't turn on, which it does if I set it low enough to kick in on my small load, so that part of the circuit seems to work fine. And yes, the bridge on the 100k trimmer is in place. I did notice something while probing the thing though. As expected, the voltage over D6 is 5.6V. However, and thus over R14, the non-inverting input to U2 is half, at 2.8V, making it's output 5.6 and thus the output of U3 roughly three times that at max voltage adjustment, which is those 17.5V I get at the output, and it can of course never go above that. Now, the reason for that U2 input beats me.
  8. 0-30V Stabilized Power Supply

    Whats the voltage drop over your 0.46 ohm sense resistor? It is past bedtime here, can think more tomorrow. But I think it could be current limit. When you remove the voltage trim pot you get really high gain, which means that the input voltage at the rightmost op amp can be low (caused by current limit) and still provide a high output voltage. If the 100k current limit trimpot is connected wrong it will always be 100k. This will mess up the current limit op amp. So I hope the solution is to put a bridge/jumper/short between pin 1 and 2 on the 100k trim pot.
  9. 0-30V Stabilized Power Supply

    Hi! I have bought the same board from the same man :-) but not built it yet. Ive done lots of simulations though. I guess this is unloaded? Repairman told me about the 100k trimpot, you need to short pin 1-2 there, did you do that?
  10. 0-30V Stabilized Power Supply

    So, I ended up getting the PCB:s from Repairman (great service there) and have put one together, I do have a weird issue someone might be able to help me with: The circuit the PCB is based on is the Liquidbyte version from the top of page 88 of this thread (http://electronics-lab.com/community/index.php?/topic/29563-0-30v-stabilized-power-supply/&page=88). The things where I deviate a bit are: The ballast resistors for the 2N3055's are 0.1 Ohm rather than 0.33 since I didn't have those available at sufficient power rating The sense resistor is 0.46 Ohm: Rather, it's a small network of two 0.56 Resistors in parallell after which there is a single 0.18 one in series, yielding 0.56/2+0.18 = 0.46 Ohms, again for availability The single 10 uF Polyester cap was also lacking, so it's replaced by two 4.7 uF ones in parallell, they turn out to measure almost exactly 10 uF My rectifier bridge is only rated at 12 Amps at 250 V, this should be sufficient though The Transformer is a 30V/4A, yielding the same 120VA Now, when I fire the thing up, I can adjust voltage fine from about zero (haven't been able to calibrate it yet) but only up to 17.56V (which may not be that exact given it's from my multimeter). Turning the trim pot adjusts down from this fine, but when adjusting up it goes to those 17.56 and stops. Now, if I disconnect the voltage adjust pot entirely the output shoots up to 40V, connecting it back makes things stop at 17.56 again. Have looked things over and can't find anything obviously wrong, maybe someone has an idea to what may be happening would be greatly appreciated! Cheers
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  13. Weird login issue

    Thanks for reporting this issue. I will check and get back to you.
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  16. Weird login issue

    So, recently joined the forum after lurking for quite some time. However, I am having a really strange issue; whenever I try to log in, it tells me my password is wrong. The first couple of times I though I had made a mistake and just changed it, but after a couple of times I made sure to copy and save the password and it sill doesn't work. Also recently tried setting it to a ridiculously simple password of six lowercase letters, and still it's wrong. Never had this issue at any forum before, unfortunately it makes enjoying this place much less accessible, having to change password each time, so anyone, please if you've had something like this, do you have a suggestion?
  17. Any body can help me in this topic. I want interface P5 RGB LED display with PIC 18F452 .
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  19. 0-30V 0-3A Latest Data Discussion

    CID/CID+ certification is requirenment is high did some one knows how i can get certified in my home counrty?
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  21. Looking for learning material

    I too wish to get tutorials about micro controllers and processors
  22. Regarding Cheapest PCB PRICE Inquiry

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  23. Circuit Diagram is given below: The circuit diagram of a three channel LED driver circuit using MAX7219 is shown below (Fig 1). C4 is an input filter capacitor. R1 is the resistor used for programming the output current. C3 is the output filter capacitor. C1 and C2 are the storage capacitors of the internal charge pump circuit. A logic high at pin 5 will enable the IC and a logic low on the same pin will drive the IC into shutdown mode. In the shutdown mode, the quiescent current is almost equal to zero. With the used value of R1, the LED current per channel will be 25mA. When powered up the MAX7219 operates in 1X mode i.e, the output voltage will be equal to the input voltage. If this output voltage is enough to regulate the current through all LEDs, the IC remains 1X mode. If the output voltage is not sufficient enough to regulate the desired current through the LEDs, the device automatically switches to the 1.5X mode where the output voltage is 1.5 times the input voltage. This process is repeated when ever the IC is powered up or awaken from shutdown mode. Can this circuit work? Actually,the LED driver in this circuit is CAT3063,however,I can't found this mode. I would like to use MAX7219 instead of CAT3063. Please give me some help! Appreciating!
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  25. Regarding Cheapest PCB PRICE Inquiry

    Recently, i found a company called jlcpcb. It’s very cheap, 10pcs boards. 1.2mm thick, 1-OZ copper, 6/6-mil outer (0.1525mm) just cost $2. Cheap price and lots of options regarding board thickness, colour, etc. None of my boards have ever had a manufacturing issue. I think there are no difference with i bought from others. Shipping time (dhl)lasts 3 days.
  26. 0-30V 0-3A Latest Data Discussion

    Oh. Ok. I thought your fix was for the peak that occurs when you are in current limit mode and turn the supply off (since the current limit function collapses faster than the output is pulled down. Then it's ok. Turn on transients shouldn't be as tricky. 0.2 volt on the base of a 2n4401 shouldn't open it, so it should be ok.
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  28. 0-30V 0-3A Latest Data Discussion

    I cannot remember my fix for the "on" voltage spike. If you remove the negative supply then you will not be able to limit shorted output current less than about 0.43A since the transistor that replaces the diode cannot go lower than its max saturated output of about 0.2V. 0.2V/0.47 ohms= 0.43A.
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