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  1. chopnhack

    Why do my leds blink on this power supply?

    First question that comes to mind is why did your supply die in the first place? Is it possible the LED driver has become faulty and is drawing too much current thus killing your supply? Are you able to take a amperage reading while the circuit is powered to see what kind of draw is occuring...
  2. chopnhack

    Toner transfer for PCBs having BGA packages on them

    To each their own, I have used both and I am currently in favor of the muriatic acid because of cost, ease of use and environmentally friendly disposal. I didn't think it was faster, but when I thought back to when I used to use the ferric chloride solution (over ten years ago) - I did remember...
  3. chopnhack

    Toner transfer for PCBs having BGA packages on them

    I've had no problems, but gloves are the best precaution, safety glasses and a respirator too! This mixture is more environmentally friendly in my opinion - it can be neutralized with baking soda and disposed of. If you really want to, you could bring this mix to the junk yard for copper...
  4. chopnhack

    Toner transfer testing

    Awesome, thanks for the follow up! I stopped using the ferric chloride in favor of the hydrogen peroxide/muriatic acid - the latter is far more easily obtained. H2O2 from grocery store and muriatic acid from home supply store or pool supply (hydrochloric acid). Etching is slightly slower, but...
  5. chopnhack

    Toner transfer testing

    Pilko, in retrospect, the printing is not usually the problem - its the etching with undercutting of fine lines. Have you etched any boards with the fine lines you have shown?
  6. chopnhack

    4 Digit 7 Seg LCD Display Datasheet

    Unfortunately some of the Chinese/Hong Kong sellers purchase their wares from various sources and do not deal direct with the factory or have the manufacturer's datasheet. Do you have relations with other sellers in the Pacific that you can ask to look for you?
  7. chopnhack

    Bench Power Supply

    That one is also obsolete. I am looking at the LT1083 - 7.5A max, three terminal device. I haven't thoroughly searched yet, but the datasheet didn't seem to have anything about using the regulator as a negative supply. If I can not find a negative complement, there is a 5 pin LT1085/LT1185 +/-...
  8. chopnhack

    Bench Power Supply

    Found out that the LM333 are obsolete. Digikey had a listing with "call" and TI's datasheet are marked obsolete.
  9. chopnhack

    Temperature Control Help

    Hi Charlie, does your mechanical engineering education include HVAC? I ask because this would seem more like homework help, for which the forum has an excellent section to cover this. 175 degrees F is fairly hot for ~1400 cu. inches. Do you also have to build the enclosure? The material the...
  10. chopnhack

    Bench Power Supply

    Aside from just a heatsink, have you thought of using computer fans to assist the cooling?
  11. chopnhack

    Bench Power Supply

    I was thinking more along the lines of having to rid the IC of heat - specifically at the extremes of low voltage and high current.
  12. chopnhack

    Bench Power Supply

    Thanks Dave, off I go! :-)
  13. chopnhack

    Bench Power Supply

    Thanks Dave, I will look at in depth. Is the large amount of power wasted not really much concern with linear regulators? Konstantine mentioned that linear is the way to go with bench supplies because there is less noise and that becomes very important with amplifiers, but the inefficiency...
  14. chopnhack

    Bench Power Supply

    That is probably why I was having such difficulty in producing a schematic, there was something that just didn't seem right, thanks for the explanation! Valid points, I saw some information in the datasheet which led me to believe it was possible to do. Lack of experience brought me down this...
  15. chopnhack

    Bench Power Supply

    Tonight's question! Here is the schematic for producing a negative supply voltage from the datasheet. I assume that the ground symbol is true earth ground and not common. 1. Can someone confirm this for me. I am relatively sure of it. 2. Does this arrangement make more sense? Should the...
  16. chopnhack

    Bench Power Supply

    That is a great way to remember electron flow, thanks Dave!! I was always thinking of the arrows and would confuse myself sometimes when thinking of electron flow. Either way is fine, just need to work your way through a circuit one way or another - by checking with the opposite method you can...
  17. chopnhack

    Bench Power Supply

    I see where I goofed again - solarwind pointed it out, but I misunderstood the datasheet. I'll post a new schematic tonight. Thank you Dave! Its rather hard to find a good design!!
  18. chopnhack

    Bench Power Supply

    I think I get it - its a vector thing - its just the direction of flow, so the negative rail is just more negative than common, thus charge flows from more negative to common. Really no different than flow of charge moving from common to positive rail, if I got it right. And if the above is...
  19. chopnhack

    Bench Power Supply

    Hi Dave, my thought was to rectify the AC from a transformer and use a buck converter - thus providing the necessary isolation from mains.
  20. chopnhack

    Bench Power Supply

    My concern is that in using this power supply with μ-processors that only need 5v, this unit will have to bleed off ~18-19v, if I have peripherals hooked up to the PIC and am using 1/2A, that would be ~9watts of heat lost. This is why I was thinking of perhaps using a SMPS supply. They are...
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