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  1. CDRIVE

    PIR operated DC motor project odd behaviour help

    Yes, the Diode position is what you want. When the DMM is switched to Diode test or Ohms the device/component you're testing should never be powered. Not doing so can damage your DMM. Anyway, your reading (.567V) = 567millivolts. That's about normal when the Negative (Black) meter lead is...
  2. CDRIVE

    PIR operated DC motor project odd behaviour help

    Yes, you're correct. The product image doesn't include that component. It was probably added in current versions. Since I can't see the bottom of the board I can only give you an educated guess of what it's for. Considering it's location on the board I believe it's a reverse polarity protection...
  3. CDRIVE

    PIR operated DC motor project odd behaviour help

    OK Ivan. That test confirms that there's a current limiting resistor on the board because I don't think any of the OptoCouplers I'm familiar with employ an integral resistor. You may ask what this means to you? It means that you should be able to connect the GSM ringer output directly to the...
  4. CDRIVE

    PIR operated DC motor project odd behaviour help

    Does this help? Chris
  5. CDRIVE

    PIR operated DC motor project odd behaviour help

    The Opto input is the White (2 pin) connector. Pos(+) is the top (Red) wire. Neg(-) is the same White connector (Black wire) directly under the Red. A 560Ω will work fine. Chris
  6. CDRIVE

    PIR operated DC motor project odd behaviour help

    I can find no reference for a 817cu546 opto. Refer to the pictorial. (1) Disconnect all inputs and outputs. (2) Tie a 470Ω resistor (Rs) to the Positive (+) opto terminal. (3) Connect the positive lead (Red) from your 12V supply to the unconnected end of Rs. (4) Connect the negative (-)...
  7. CDRIVE

    PIR operated DC motor project odd behaviour help

    Ivan, please select one. ( 1 ) You've been in a coma for the last 7 months. ( 2 ) Your dog ate your PC. ( 3 ) You've been busy because Bosnia & Herzegovina has suffered a Zombie Apocalypse. ( 4 ) You forgot that you started this topic in February. ( 5 ) All of the above. That said, I'm curious...
  8. CDRIVE

    Drop voltage on transistor base

    If your merely desirous of switching Q1on and off why are there two paths biasing the b,e junction?:confused: Are these components that you're adding or are they OEM? Chris
  9. CDRIVE

    Alternative Materials for Homemade Circuitboards

    JMPO,... but for neophytes this is by far the most logical choice. It's been mine for (one - off-s) for decades. A proper soldering iron, solder and an Exactoknife is all you'll need. That said it's doubtful that you can build an intercom (hard wired or wireless) cheaper than you can buy a...
  10. CDRIVE

    Where to start

    Yet another option: https://sourceforge.net/projects/gcbasic/ If using the Synwrite GUI it compiles GCB to pure .HEX and .ASM with a click of a button. Both of which can be made visible in the Synwrite IDE, side by side with the GCB code. There are lots of vids on Youtube plus a very active...
  11. CDRIVE

    Serial communication problem.

    Constantine, I skimmed over the MAX3222/MAX3232/MAX3237/MAX3241 Datasheet and noted the following quote: Perhaps this is the chip you need? Personally I would not feed true RS232 voltages/currents into an un-powered chip without knowing how those nodes will react while the chip is un-powered...
  12. CDRIVE

    Serial communication problem.

    That's a difference of 1/10th of a volt. It's still well above the minimum TTL spec to be recognized as a valid TTL logic 1. Constantine, are you using a hardware RS232 port or a USB/RS232 converter? On second thought I just took a peek at this image that you posted and it certainly looks like...
  13. CDRIVE

    Serial communication problem.

    The NPN really should have a reverse biased Diode between the base - emitter junction. Otherwise I see a short life span in its future. Chris
  14. CDRIVE

    Serial communication problem.

    Constantine, your concern over your logic being inverted is misplaced. A logic 1 on from the RS232 TX is Negative which is bypassed by D1 and Q1's BE junction will be reversed biased. This will placed Q1 OFF. This produces +5V at Q1's Collector. This is a TTL logic 1. So, as you can see your...
  15. CDRIVE

    Building my own bench drill

    Miguel, I'm sorry you found my last post offensive. It would appear that humor there is also in short supply. That said ... nice work! Chris
  16. CDRIVE

    Adding PWM speed control to Linear Actuators for TV control

    I think you misread my post. I asked why not a PIC,.... not a Picaxe. :) Chris
  17. CDRIVE

    Oscilloscope used as a component tester

    THIMC, While your posts are of interest it deserves its own topic. Hijacking another member's topic is not good or accepted forum etiquette. Chris
  18. CDRIVE

    Adding PWM speed control to Linear Actuators for TV control

    Josh, just curious why you abandoned a PIC for an Arduino? Chris
  19. CDRIVE

    Health Care is so damn expensive...

    Oh my how this topic is depressing me. This past January I had what I thought was a very bad flu. Since then I've been repeatedly poked, MRI'd, CAT Scanned, Xray'd and poked some more. One specialist after another, biopsy and poked some more. All with no answers. I'm now seeing a neurologist and...
  20. CDRIVE

    Certificate issue with electronicspoint.com

    I consider myself fortunate. I must have missed the time period of the certificate warnings. I'm already an over wound spring. Chris
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