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  1. CDRIVE

    Is this true or false

    Quite frankly I can't even fabricate a plausible technobable answer to this question. I do know that I've read quite a few crystal radio articles and threads where guys in the UK were begging for 1N34's because Schottkys didn't perform as well. Yes, they worked but not well. Here's a guy that I...
  2. CDRIVE

    Is this true or false

    I think we have to make a point of differentiating available airborne power vs available voltage. The basic 2 requirements to make a crystal radio is an RF detector (Diode) and a Crystal earphone. Since its inception and to this date the 1N34 Germanium Diode still reigns king. Schottky diodes...
  3. CDRIVE

    Video Distortion Over Cable Distance

    The industry impedance standard for CCTV is 75Ohms. The camera's output Z = 75Ohms. The cable impedance also equals 75Ohms. Finally the monitor's input impedance should be 75Ohms. Any mis-match from any of these three components can cause what you describe. Some monitors have a switch or...
  4. CDRIVE

    Wheel movement sensor / alarm

    Thanks for the pix. Do you wear a respirator or is the material misted to hold down the dust? Anyway, where are you on this project? Do you have a schematic for that control panel? Chris
  5. CDRIVE

    Lithium battery charger

    Here ya go. :p
  6. CDRIVE

    Battery powered Current sink with low voltage cutoff

    Kris, you never cease to amaze me how fast you design your circuits. I'm beginning to think that your wife and kids don't see much of you! :p Chris
  7. CDRIVE

    software inventory

    I'm sure that bar code scanners have changed quite a bit over the years but the most basic forms I've encountered would have to be the Keyboard interface models. They use either a direct plug in to the keyboard (PS-2) port or a 'Y' adapter to share the port with the keyboard. Data from the...
  8. CDRIVE

    New Career?

    Yes, this is my opinion also but I wasn't really sure. So a Condor or a human with wings might have a problem? Chris
  9. CDRIVE

    New Career?

    I think the Faraday Shield theory as used in this video deserves further discussion. After all the shield is not earth grounded and birds don't need them. That leaves the wild card in the equation, which is the Helicopter, which the suit is grounded to. Who wants to go first? Chris
  10. CDRIVE

    220v LED DIMMER??

    Note: You will find large font and large red font in this reply. When I do this it usually indicates DANGER! Go back to my last post. I've edited the schematic to include vital information regarding dangerous node potentials. I've also included a second schematic with plots. That said, I'll...
  11. CDRIVE

    220v LED DIMMER??

    I was thinking of something like this. I took the 555 PWM from here. http://www.reuk.co.uk/LED-Dimmer-Circuit.htm They're running the 555 @ 250Hz but I jacked it up to 2.5KHz here. Please note that my opinions about circuits like this connected directly to the mains haven't changed. I...
  12. CDRIVE

    220v LED DIMMER??

    Let's back up for a moment and review a few things. A common Triac dimmer is actually a form of PWM because it slices off a piece of each pos & neg cycle. Which, in effect shortens the on time that the load is receiving current. It doesn't work well for LEDs because LEDs are fast and there's no...
  13. CDRIVE

    220v LED DIMMER??

    Well, I don't know what R value your pot was. I was not thinking of a high value. I really don't like that solution anyway as it's yet another linear concept. It was more like thinking aloud. My good sense little voice should have said shut up until you have something viable. :D Chris
  14. CDRIVE

    220v LED DIMMER??

    I asked because I was pondering a 3 gang pot wired as a rheostat in series with R1A,B,C. The logistics of this may not be convenient though. Chris
  15. CDRIVE

    220v LED DIMMER??

    This quote is from one of your posts early in the thread. How many R1s' (10R) are there? Unless my calculations are way off R1 dissipates about 100mW. Chris
  16. CDRIVE

    220v LED DIMMER??

    On a whim I Googled "240VAC LED Dimmers". This is what I skimmed through. http://www.reuk.co.uk/240V-LED-Bulbs-and-Dimmer-Switches.htm Chicom! http://www.aliexpress.com/store/product/newest-design-self-developed-100-240VAC-led-dimmer-remote/501312_687376803.html CFL-LED/INC switch...
  17. CDRIVE

    New Career?

    But that's only because you're sane! :p Chris
  18. CDRIVE

    220v LED DIMMER??

    Huh? Is it an old 'Rheostat' design? They were high power variable resistors that belched out copious amounts of heat. It was a miracle that they were ever approved by UL or any safety compliance agency. I think they'd re-purpos as a space heater or a toaster though! :D Chris
  19. CDRIVE

    220v LED DIMMER??

    Yeah, but I sure wish BL didn't overlay all those current squiggles all over those schematics. They obscure and confuse what I want to see. Makes me dizzy too! :eek: BL, is this dimmer going to replace a wall (240VAC) switch? In other words it's not plugged into a wall receptacle but rather...
  20. CDRIVE

    alternating LED flasher using 12Vdc supply and 555 timer

    Your welcome. Here's an updated version for 12V operation. The LEDs should flash at about 1 Hertz. Each LED is on for 1 second while the other is off. Please note that it's important to observe the polarity of the caps as shown. Personally, I'd use a 555 because it would only need one timing...
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