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  1. CDRIVE

    Restoring a Regal Do-Wa-Diddy by fOXX

    Admittedly I'm late to this party and I never read the original topic. That said I should be capable of understanding this quote but I don't. Are you referring to the 'Wiper' (center terminal) as the taper? Actually, reading it again,...that makes no sense in that context either. Chris
  2. CDRIVE

    Scope

    Oh yeah that's a damn important point! I imagine there are DUT's that wouldn't like it either. :) Chris
  3. CDRIVE

    Scope

    Sometimes datasheets for transistors and other active components include example circuits of pulse tests. Many of these examples use a 50Ω load. Your 50Ω input is useful for measurements like these. A 50Ω coax cable is used in place of your probe and cable. Prior to scope manufacturers providing...
  4. CDRIVE

    Learning Unijuctions

    Yes, it certainly is a spike. I guess with only 2uF one should expect a brief pulse. It could be a handy pulse source for someone playing with time domain reflectometry. I wonder where the OP went? Chris
  5. CDRIVE

    Using Resistor as Dummy Load

    I'm not exactly sure of what you're looking for. Are you desirous of a circuit that will automatically adjust the load resistance for maximum power dissipated in the load? If you're looking for something simpler you could use a high power wire wound Rheostat. If so you would have to manually...
  6. CDRIVE

    Learning Unijuctions

    I guess after a goof like that I should post a corrected schematic and plot. I added R4 to limit the LED current and stretch C1 discharge time a bit. Chris
  7. CDRIVE

    Learning Unijuctions

    Yes Bob, that was a very lame mistake. Chris
  8. CDRIVE

    cctv re-wiring

    Post a clear photo of the rear of the camera with particular focus on the terminal block. Chris
  9. CDRIVE

    triac based 50v to 110v battery charger

    Is there a link where I can see these locos? Chris
  10. CDRIVE

    cctv re-wiring

    The vast majority of CCTV cams that I worked with accepted both AC or DC power. In fact I'm struggling to remember the last DC only model I worked with. It was that long ago. Chris
  11. CDRIVE

    Learning Unijuctions

    Huh, I guess the page didn't load correctly when I posted that because, as you say, it's still there... now. BTW, if the spice model is accurate I don't see enough C1 discharge current through the PUT to light a LED. The datasheet includes an astable example but they drive the LED with an SCR...
  12. CDRIVE

    Learning Unijuctions

    Where did the schematic go? Anyway I didn't like the way it was drawn so I was going to redraw it. That's when I discovered I didn't have a 2N6027 in my library. Actually I found I didn't have any UJT's or PUT's at all. I didn't even have a symbol for them. So I downloaded a spice model for it...
  13. CDRIVE

    A zener diode question

    Trevor, I have to click a "LIke" somewhere in this thread but I'm not settled on which of your replies it will be. You did a great job of walking him through the problem without actually doing the work for him. On second thought it's got to be this one because it ends with a "?". It's...
  14. CDRIVE

    PIR operated DC motor project odd behaviour help

    Ivan, did you make sure you clicked the drop down box and selected the 12V model? Also, when it arrives please don't power it up until you post to this thread and tell us if it came with any further instructions or tech data. In particular I want more info regarding the Optocoupler and its input...
  15. CDRIVE

    PIR operated DC motor project odd behaviour help

    Like this.. Chris
  16. CDRIVE

    PIR operated DC motor project odd behaviour help

    Do you remember when you posted this? The off delay is used to keep the motor running after the GSM receives its first ring. Otherwise the motor will be turning on and off with each ring (vibrator voltage). Chris
  17. CDRIVE

    PIR operated DC motor project odd behaviour help

    That's one of the bugaboos with Chinese direct products. Products that aren't retailed through natives in the country of sale suffer from poor descriptions to nearly no descriptions. Sending queries to the Chinese seller is an exercise in futility. You shouldn't have to do any soldering unless...
  18. CDRIVE

    PIR operated DC motor project odd behaviour help

    Ivan, the rise time speed of the 4N33 optocoupler is probably a non issue because the FET isn't being cycled on and off repetitively like they are in PWM applications but the schematic I posted still doesn't provide the triggered ON - Timed Period - OFF operation that you want. I can add a 555...
  19. CDRIVE

    PIR operated DC motor project odd behaviour help

    In this world the terms "fast" and "slow" are relative to the topic being discussed. When I said OptoCouplers are slow I'm speaking in terms of microseconds vs nanoseconds. When a MOSFET is used to switch a heavy load it's imperative that the Gate - Source voltage (that turns the fet on)...
  20. CDRIVE

    PIR operated DC motor project odd behaviour help

    J1 & P1 are connectors. Yes, they're triggered by low current DC and employ an integral OptoCoupler input. I provided links for SSR descriptions. Later I'll post a block schematic using an SSR in your application. Chris
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