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  1. P

    Peel-off paper sticker circuit?

    OK, thanks for responses.
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    Peel-off paper sticker circuit?

    Thanks for replying, RFID tag. Probably the coolest part for me is how the passive chip gets charged by the transmitter radio wave, to ping back data.
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    Peel-off paper sticker circuit?

    Hi, I'm attaching image file of this peel-off paper sticker circuit (Image URL option from menu shows red X in post Preview, despite working link). What is this and what would it be used for? Thanks
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    555 on/off circuit for 5v motor (w/ schematic)

    Thanks Alec for your explanation about the cycle. If low trig 2 sets the latch and output 3 goes high, then this is an active-low circuit. Following your post, I see how resistance from 100K creates longer "off" time as cap is being discharged, and looking at pos/neg direction of diodes it's...
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    555 on/off circuit for 5v motor (w/ schematic)

    Chris thanks for that tip; collector current is around 120 mA and base resistor current around 10 mA with 470 ohm resistor, so that seems like good saturation. I won't connect motor directly to 7v power because that will fry motor. There must be enough voltage drop with diodes and NPN that I'm...
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    555 on/off circuit for 5v motor (w/ schematic)

    That's great, thanks. Outputs 5.5v which is perfect for 3 - 6v motor. At first with your revision, I was frying yet another NPN until I decided to remove the connection between between collector and pin 8 (V+), thinking that putting 2 V+ connections to 1 collector wasn't a good idea. Then...
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    555 on/off circuit for 5v motor (w/ schematic)

    Thanks Alec, Chris, circuit/motor working great, 2 seconds on, 8 off, fairly consistent too. The capacitor's + pin is connected to + terminal of D2, like Alec's schematic. It's not connected to V+. (I can see why you said that...that wire is orange wire bridging V+ sections on breadboard.) I'm...
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    555 on/off circuit for 5v motor (w/ schematic)

    Where does the negative terminal go then? Thanks. Re: Cdrive, the base resistor is connected to pin 3, not pin 4.
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    555 on/off circuit for 5v motor (w/ schematic)

    thanks for looking.
  10. P

    555 on/off circuit for 5v motor (w/ schematic)

    Yes that's what I have. And pin 3 output is also going to 20/100K resistors which are sharing a junction like your schematic.
  11. P

    555 on/off circuit for 5v motor (w/ schematic)

    Chris/Bob, I replaced NPN and re-wired. Wiring with Chris' mod I get constant .5 v on output with no LED blinking. Wired with Bob's original, I'm getting 5 volts on output, 2.5 mAh at emitter, 4 amps at collector (using #18650 batteries in series), and LED blinks on/off but motor's not running...
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    555 on/off circuit for 5v motor (w/ schematic)

    Thanks Alec that timing is perfect with an LED, and I'm getting 4.8v from the emitter junction, but it is not powering the 3v motor (even LED is dim). I've checked all leads and tested the motor, nothing. I have a feeling it's not getting enough current as I'm reading 2.7 mAh from emitter...
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    555 on/off circuit for 5v motor (w/ schematic)

    This PWM experiment has 6v coming out of NPN emitter (when "on"), which powers a 3 -6v mini water pump. Circuit works, but I want less "on time", and more consistent cycle, as compared to LED output, which is pretty consistent. I've changed values of capacitors/resistors, and the cycle varies...
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    Magnet Alarm Circuit Board, Battery Power

    What does this inductor do as far as being connected to the iron cap that is attracted to the external magnet? How does the piezo make a pulsing sound?
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    Magnet Alarm Circuit Board, Battery Power

    There's no crystal on circuit board, so oscillator must be RC, tuned to a frequency for piezo, but how does it make pulsing sound? I just unwrapped black cylinder that external magnet (door open/close detector) is attracted to, thinking there might be a crystal, but found copper wire coil. What...
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    Magnet Alarm Circuit Board, Battery Power

    Does the piezo make pulsing sound because circuit is RC oscillator? Oscillators have to do with tuning to a specific or range of frequencies, so why is a magnet motion detector an oscillator circuit?
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    Magnet Alarm Circuit Board, Battery Power

    thanks for responding. YL3710 I couldn't find anything on that either. Does the piezo make pulsing sound because circuit is RC oscillator? Is J6 transistor?
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    Magnet Alarm Circuit Board, Battery Power

    Someone please respond about how is this an oscillator, and RC or crystal type? The piezo alarm "pulses." Is this PWM?
  19. P

    Magnet Alarm Circuit Board, Battery Power

    Thanks guys, I'm attaching close-ups of reed switch (back), front of CB, and string of LED lights attached to device that works great. What I thought was internal battery (black cylinder) is not; it's what the external magnet is attracted to though. Does this cylinder have oscillator crystal...
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    Magnet Alarm Circuit Board, Battery Power

    hevens, taking apart your GE receiving station sounds like a good idea. I'm just doing this for fun, to learn. The blue thingy is LED. Reed switch is in back of CB, not pictured, but that doesn't have anything to do with battery connections. I just mentioned it in explaining device: magnets in...
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