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  1. chopnhack

    I want to learn about electronics!

    I find that to be the case sometimes as well and what I really have distilled from the experience (time and time again) is expectations. We are expecting to learn about something specific, perhaps how to build a project and the teacher is taking us from the beginning to get to that stage, but we...
  2. chopnhack

    I want to learn about electronics!

    I have the old version with some outdated projects. I am very interested to see what you think of the new version. For the price it is really a great starting point - it's what got me interested in electronics when I was younger. A good mix of theory and application in the right amounts. Let me...
  3. chopnhack

    I want to learn about electronics!

    It's a long road to learn solo, but there are many here who can help you with specific questions as you read and learn and stumble on something. For books I can recommend Getting Started in Electronics, Make, et. If you search around this website you will see some resources have already been...
  4. chopnhack

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

    Ah!!! Many thanks Blue - now I have to chase down that rabbit hole. Talk about design creep... I must say that the op-amp supply has me intrigued. I will start researching that later today. Hi Dave, many parts of my schematic are not of correct spec due to the limited varieties available in...
  5. chopnhack

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

    Hi all - continuing on the bench psu build, I have started to play with the design in spice to get an idea of how things are working and what purpose they serve in the schematic. According to the nuts and volts author whose plan I am loosely following, using a zener of 1.225v from the adjustment...
  6. chopnhack

    RthetaJC - top, bottom??

    Thanks Harald, essentially taking into account the worst case scenario and heatsinking for that.
  7. chopnhack

    Regulated 15V Power supply scheme

    What are the specs of the transformer you found and what kind of appliance/device did it come out of?
  8. chopnhack

    RthetaJC - top, bottom??

    Thank you Harald, I was trying to calculate out the numbers to see if forced air would be required. I intend to use a solid aluminum chassis, probably about 1/16" thick and attach the LDO directly to it. Here is a link for the pdf of the LM1086-5. The section is on page 5, 6.4.
  9. chopnhack

    RthetaJC - top, bottom??

    I noticed that the datasheet of an LDO give the RthetaJC of the top at 16.1 deg C/W and then gives the bottom in two parts, one for the control section and one for the output section being 1.5 and 4 deg C/W respectively. When calculating for power dissipation and determining heatsinks, are we...
  10. chopnhack

    Flickering flame simulation with PIR motion sensor - mostly need help with transistor, I think

    You actually do not need more than one flickering LED per group in series. See one of my old threads where I learned this. So now you just have to make sure you have enough voltage to accommodate however many LED's in series to make up for their Vf. If the voltage will not be sufficient then you...
  11. chopnhack

    LED stays on when it shouldn't. pulling my hair out.

    Good job Dorke! Looks like the resistor is enough to decrease the current to below the threshold required for the LED to light. Please note Martin that this does not mean that there is zero voltage present, just that it's below the LED's threshold to light. That may be all you need though.
  12. chopnhack

    Scavenging MOT's for bench power supply use?

    LOL, that is inventive Colin!
  13. chopnhack

    Scavenging MOT's for bench power supply use?

    I would try that Colin, but since the output is high voltage, kv in this case, I don't think it would be safe and I do not have any insulating tapes that go over 600v. I agree that this would be the simplest approach, but I was hoping someone with theoretical knowledge would be able to comment...
  14. chopnhack

    Scavenging MOT's for bench power supply use?

    I was contemplating re-purposing some microwave oven transformers that I have on hand. They are beastly things, but in my research I have discovered that they can not be used for extensive time periods because they operate in saturation? Can someone explain this to me? My intent is to rewind...
  15. chopnhack

    Op-Amp selection for inverting source signal - Bench PSU build

    LOL, that actually took me a sec. :D:p Yes, things of this nature are certainly cheaper than they used to be due to the massive amounts of manufacturing in China. Check out these SPDT, cheaper than any SPST I could find! I am going to order two lots, they look very useful for this project and...
  16. chopnhack

    Op-Amp selection for inverting source signal - Bench PSU build

    That is a sweet unit, but at over $400 delivered, way outside my budget - LOL. I can only imagine what it went for new!! I am not sure on the transformer yet, I really have to spend some time and come up with an anticipated total energy consumption list and then decide how much headroom I want...
  17. chopnhack

    LED stays on when it shouldn't. pulling my hair out.

    I am too, I suspect a diode in series would solve the problem. I would wait for further advice from some of our masters around here. While you are waiting, I would use your multimeter and start taking some readings like I mentioned before.
  18. chopnhack

    LED stays on when it shouldn't. pulling my hair out.

    I know this is obvious, but I will state it anyway. If the LED stays lit and dims over time, yet stays lit, it is receiving current and is the low point to drain it away. With mains disconnected, can you easily remove the charging LED from the circuit? This way you can test what current runs...
  19. chopnhack

    Op-Amp selection for inverting source signal - Bench PSU build

    Thanks Hop! This makes a lot more sense now. I was wondering how this small unit was measuring the high amperage without burning out. There is a built in shunt, its a short loop of a thicker copper wire. As long as the polarity is connected correctly, it will give a reading. Quite well...
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