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  1. chopnhack

    Resistance of Primary Winding of a Transformer

    Is the resistance of the primary winding of a transformer responsible for preventing a short? I was thinking about how we plug our appliances into mains voltage and typically its reduced via a step down transformer. The transformer itself is simply a primary and secondary winding. The winding...
  2. chopnhack

    Converting a projector from incandescent to solid state?

    My parents have unearthed an old 35mm slide projector along with literally thousands of slides. After watching a few hours, the bulb of course blew the next day when they went to view some more. They asked me to find a replacement bulb which I did, but at some outrageous prices. New bulbs ~$56...
  3. chopnhack

    PCB Cleaning after Soldering

    How do you clean your PCB's after soldering? If you were preparing to spray a conformal coating? I was thinking of using the coating to prevent oxidation for one of my projects that will be in a harsh environment. To prepare for the coating, the substrate needs to be clean and free of residue...
  4. chopnhack

    Anyone else waiting on Christmas?

    I don't know about you, but I got my Dr. Who fix this year - I watched all of the current Dr. Who going back to Chris Eccelston! Eagerly anticipating the Christmas special, although, the new doctor is a bit of wanker. I think the feel of this entire series was one of youthful energy and...
  5. chopnhack

    Christmas Decoration Repair

    Before anyone blurts out, "Why didn't you just buy a new strand of lights/get a new one, etc." I will explain briefly that the decoration in question (a 6' swag style bow with a red bow/white swags with matching lights) has hung from the front of the house for some years. When the store bought...
  6. chopnhack

    PCB Design Considerations

    chopnhack submitted a new resource: PCB Design Considerations - Tips on designing PCB's Read more about this resource...
  7. chopnhack

    Dryer not spinning

    So my job tomorrow is to fix a dryer that is not spinning. That is all I know from the complaint. I will first start by checking to see if the breaker has been thrown. If breaker good and outlet has voltage across it, I will check resistance of the door switch to make sure it is closed when...
  8. chopnhack

    Holiday PCB production schedules?

    Does anyone know if there are better times to put a board in for production with the folks in China? My guess is that there is a huge amount of work being sent over around this time of year or perhaps wrapping up some large orders. Would you put in a board order now or would you wait? Curious...
  9. chopnhack

    Verizon and supercookies

    In the states we have a massive provider of internet,tv and telcom services called verizon. There was a recent article about them using supercookies that you can not disable - apparently they inject the code in on their end. Interesting read: Verizon
  10. chopnhack

    Jack-o-Lantern

    chopnhack submitted a new Showcase Item: Jack-o-Lantern Read more about this showcase item here...
  11. chopnhack

    Capacitive Reactance Circuit

    Well I couldn't have simply stated that I wanted to drive 1 LED off of mains as the title and hoped to have survived! :D LOL It's trite, but I have a device that takes a red colored small based bulb which I am having a hard time locating. I thought instead, with some of my new knowledge, why...
  12. chopnhack

    Rain Sensor Status

    I developed an idea after toying with a two transistor flasher :) The components are not completely spec'd I just wanted to get some opinions on feasibility. Taking the input from a normal closed switch with 0 VAC - call that the dry state for which I want a green LED to light up, the same...
  13. chopnhack

    Sinking and Sourcing Current Supplies?

    Does this diagram illustrate sinking and sourcing supplies? My text uses conventional current supply and states that: 1.5.3 A S S O C I A T E D V A R I A B L E S C O N V E N T I O N Equation 1.4 implies a specific relation between reference directions chosen for voltage and current...
  14. chopnhack

    Resistors in Parallel

    This is an algebra issue - I have written what I thought would be the correct formula for Network C - the computer doesn't like the input method, claims that it failed to parse the equation.... It liked my other two!! Mind you, this has to be in terms of R Parallel resistance - there are two...
  15. chopnhack

    When is 1 watt not 1 watt?

    You are given three resistors: two 4Ω resistors and one 6Ω resistor. What is the value in Ohms ( Ω ) of the largest-valued resistor that can be fabricated by combining these three resistors? 14 - correct What is the value in Ohms ( Ω ) of the smallest-valued resistor that can be fabricated by...
  16. chopnhack

    How to setup KVL equations with element laws?

    6.002x is great! I understand the concept and things are actually starting to make sense!!! Too bad I can't keep up with the math :eek: I've read over 70 pages of the text, watched a few hours worth of videos and some independent research and have concluded that I am fairly thick :rolleyes::D...
  17. chopnhack

    Stranded Hookup Wire and Logic Circuits?

    I wanted to buy some hookup wire for further experimentation and came across a review stating that it was not a good idea to use stranded wire for logic circuits. Is there any truth to this? I was thinking of buying some 22 ga. stranded wire as it would be more flexible than solid core. I...
  18. chopnhack

    Twin LED Flasher

    I built the schematic below: The LED's do indeed alternate flashing, but I noticed that they are not completely off between flashes. I probed the LED's to see what was going on, and the meter registered 2.5vdc when off! Looking at the schematic I guess that the capacitors and the 22k...
  19. chopnhack

    How Transistors Work

    As I try to learn more about these components, I stumbled onto this site. Can anyone review the information and let me know if this is a valid viewpoint or if its bunk. The author did state that it is his opinion as I recall, but so far reading it, it was making sense...
  20. chopnhack

    Can wall wart's be damaged by diodes?

    I was using my w.w. to power a breadboard and didn't notice that one of my jumper wires was in the wrong location. The LED did power up, but the light gradually diminished. I disconnected and found the misplaced jumper, but instead of having 16.4v I now only had about 2v. Any ideas of how that...
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