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  1. chopnhack

    How do I calculate the ESR of a capacitor please?

    Wow..... I am shocked that they would have you designing a SMPS at third year! Perhaps this tool can be of some use: Texas Instrument Is Unilag that difficult? Or is the teacher not doing a very good job at educating?
  2. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Today's madness brings some design alterations... maybe.. After some thought and some excellent suggestions I have come up with condensing multiple supplies into a compact, usable form. The schematic above is partial - I really just wanted to ask a few questions about the approach. I thought it...
  3. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    LOL, negatory good sir - I have not purchased anything else other than the xfmr's because they were such a good deal and then some ancillaries, like binding posts, fuse holders, sheet aluminum. I figured I should nail down the design first before placing the order to be economical :D Well...
  4. chopnhack

    RthetaJC - top, bottom??

    Wow, that is awesome Harald! I think I should report their misdrawn bridge diode schematic! In, I believe their 371 datasheet someone on the forum spotted it drawn as a ring modulator :eek: Any prizes for helping? Maybe they can send me a few samples :p:D
  5. chopnhack

    Help purchasing Capacitors

    Rubycon, Nichicon and Panasonic are all very good quality capacitors.
  6. chopnhack

    Soldering Recommendations

    That is a soldering gun, not an iron. I do not think that it can give you the control you need. The dirty tip is probably a result of initially too high of a temperature and the flux burning off leaving behind residue, while the iron does not have a high enough thermal reserve and thus can not...
  7. chopnhack

    Soldering Recommendations

    Welcome to the forum. Can you give us a link of your iron and tip that you are currently using. I suspect that it is too small a surface area to rapidly transfer the heat to those larger pins. Some solder paste, fine solder and a hoof tip is what I use, even for bigger tabs, as fast as I can...
  8. chopnhack

    Questions on LT3080

    Thank you, I saw that later in the datasheet. I modeled the basic variable supply in spice, but the output was not adjusting as expected. Regardless of what value I use for the set pin resistor, I get a consistent 10.97VDC out... Any clues as to what setting in spice I might be missing? Again...
  9. chopnhack

    Questions on LT3080

    Indeed, it makes it hard to follow along when they obfuscate the internals!! But I guess that is ok, it may be a trade secret. Thanks, I was pretty enthused when I found it, but I am not so sure after reading this statement from the datasheet: << The LT3080 can be operated in two modes...
  10. chopnhack

    Questions on LT3080

    Hi Adam. I am not sure I follow you on this one. The Vcontrol pin is hooked up to the op amp and the ammeter symbol device (not sure what that is supposed to be). The pass transistor is directly connected to the input voltage.
  11. chopnhack

    Questions on LT3080

    Thanks Hop, I should have realized by now that C1 was a filtering capacitor...:oops: Would conventional flow look like this then? Incoming voltage filtered by C1 until it was full then feeding to In and Vcontrol, stopping at the pass transistor until its gate is activated by the op amp. I am...
  12. chopnhack

    Questions on LT3080

    Hi all, doing a little research on LDO linear regulators and came across a five pin package that I was not familiar with. http://cds.linear.com/docs/en/datasheet/3080fc.pdf In the schematic above they show Vcontrol being tied to the IN pin. In the pinout diagram they show Vcontrol as a...
  13. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Truest thing ever said of spice regarding modeling and true to life sims: << sceadwianNew Member Jun 1, 2009 499 37 Those parasitics also don't fully characterize the truly complex nature of an IC. Most IC models for Spice aren't actual TRUE full spice models for the circuit, or they would take...
  14. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Makes more sense :) and its priced right. I did see recommended operating current and will change R7 when I get my hands on some. (Thanks for reminding me in case!!!!) Agreed, I think I will play with the values of C5 to see if we can accomplish that. These were the two xfmr's that I got for...
  15. chopnhack

    Considering a design change

    I like the fluid option better, similar spacing. I do like the older version better, the border seems to delineate the areas better. Now they seem to float abit, but no big deal, I am here for the content ;-) Thanks for all you do Ian!
  16. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Here is the setup: The transformer provided 23.45 VAC unloaded, so the caps I picked where rated at 35vdc, close to max, but I figured under load the xfmr would have some voltage drop so that should keep it safe. Perhaps in the psu it would be more prudent to go with 50vdc for the extra...
  17. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Hahaha, curious eh?! If we do this, the current across the resistor R7 drops from 2.4mA at inrush to 0.286mA at steady state - and the zener does not get enough current. As compared to when the D13 is left in, current across R7 starts at zero and ramps up in a saw tooth pattern to 18mA. This...
  18. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    I don't have the precision v. reference shunt on hand yet, but I tossed it into spice. Interestingly enough, I left the diode and caps in as they seemed to be effective when I reviewed the circuit in preventing negative voltage during one half of the sine wave - proved to be correct in spice...
  19. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Thanks ak ;-)
  20. chopnhack

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Thanks Hop. I did look at the schematic when I visited the page and thought, I wonder if I could simply just swap in a 1.225 zener in place of the 9.1v zener in the schematic. I haven't quite decided what I will do - continue along this line of thinking and produce the simple linear regulator...
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