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    Wireless mouse internal antenna length - crucial?

    Hello. I accidentally broke the antenna inside my wireless mouse -- at least I'm pretty sure it's an antenna. It's about 0.5mm diameter and runs ~115mm around the perimeter of the top of the PCB, then is soldered through on both ends. About 1-2mm broke off, and I thought I'd fix it by...
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    [SOLVED] Okay to connect in-circuit programmer and COM port to PIC at the same time?

    Hello. I'm learning to use the UART/USART on a PIC microcontroller, to interface with a computer for the first time. Every time I want to re-program the PIC, this is what I do: Disconnect COM port from breadboard. Connect Pickit 3 USB programmer to the PIC. Program PIC. Disconnect programmer...
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    PIR motion sensor - analog output - should I limit output current?

    Okay: https://pewa.panasonic.com/assets/pcsd/catalog/napion-catalog.pdf Has the diagram you posted (no resistor). But this one (the "Design Manual") has two diagrams with the resistor, on page 20 and 25...
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    PIR motion sensor - analog output - should I limit output current?

    No that is the analog diagram (digital is attached to this post). Oh, and sorry about my mistake on ADC input impedance (10K is the recommeded _source_ impedance for the ADC). The input impedance on my current chip (PIC 12F1822) is actually about 7K (@5V Vdd). Still -- that's even lower. Can...
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    PIR motion sensor - analog output - should I limit output current?

    Hello. I bought a PIR motion sensor with analog output (Panasonic AMN22112). Datasheet: https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electric%20Works%20PDFs/AMN%20Design%20Manual.pdf Digi-Key page: https://www.digikey.com/product-detail/en/AMN22112/255-1806-ND/735389 The datasheet...
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    [SOLVED] Does current rating of wire double at 50 percent PWM duty cycle?

    Hello. Can you run twice the rated current through a wire if the signal is a PWM at 50%?
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    Hitachi HD44780 LCD - I unplug Vdd but LCD stays on?

    Thank you very very much!! Great, informative reply!
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    Hitachi HD44780 LCD - I unplug Vdd but LCD stays on?

    I'm working on a project controlling an HD44780 LCD with a PIC microcontroller. The data lines on the LCD get fed from a 74HC164 shift register that if controlled by the PIC. I had it running, but wanted to keep the LCD off until the shift register has a known value, so I unplugged Vdd on the...
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    Solder iron tip -- is it okay to not insert all the way into iron?

    I hadn't even considered the tip getting less heat. Understood. I'm more concerned about the iron getting too hot and damaging itself...??? The plating also protects the copper from being dissolved by the molten tin in solder. I didn't grind mine till it was too oxidized to work anymore. As...
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    Solder iron tip -- is it okay to not insert all the way into iron?

    I've seen two kinds of soldering iron tip: 1) short tip with threads that screw into the iron. 2) long tip that slides all way into the iron, and is held by a set screw. My question is about 2): Would it be okay to run the iron with the tip only inserted half-way into the iron? I'm asking...
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    Record audio above human hearing frequency-- how?

    Hello, I need to build a circuit that can record audio frequencies up to 45kHz. I have two main questions: 1) What kind of microphone do i need? 2) What kind of circuit do I need in order to make these sounds audible to a human? A circuit that can lower the input frequencies by about 20kHz...
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    Smoke alarm -- low battery beep -- timed how?

    All i'm trying to do is figure out why my neighbor's smoke alarm seems to be beeping at different intervals. I've timed 30 seconds in between beeps, all the way to 3 minutes. I don't see how it's possible for a timer that's supposed to go off every 30 seconds to take 3 minutes to go off. So i'm...
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    Smoke alarm -- low battery beep -- timed how?

    Yes -- i did mean the battery-powered kind. Thank you, but all i want to know is how the low battery beep interval is timed. And how far off of that time it might go if the battery were _very_ low.
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    Smoke alarm -- low battery beep -- timed how?

    Hello. Can anyone please tell me what the typical circuit or mechanism is that times the beep that a smoke alarm makes when the battery is getting low? And say the battery is getting _really_ low -- how much might that effect the timing? For instance -- if the timer is supposed to beep every 30...
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    [SOLVED] MicroSD (or SD card) - through hole connector??

    Thank you, but I meant to say "perfboard" instead of protoboard (I just realized they aren't the same thing). So perfboard... pre-drilled 0.1 inch spaced holes... any ideas? (i have changed proto- to perf- in my original post)
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    [SOLVED] MicroSD (or SD card) - through hole connector??

    Hello. I'm trying to find a MicroSD card connector to use on perfboard, but it seems that they are all surface mount. Can anyone point me to a through-hole MicroSD card connector? If not, how about a through-hole SD card connector? (EDIT: changed "protoboard" to "perfboard")
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    [SOLVED] Transistor as audio amplifier - no negative supply needed?

    Noob question here... I've seen some audio amplifiers that use a standard BJT as the amp (example attached). I'm wondering how this can work without a negative voltage supply. I thought audio had to go above and below zero volts? I guess it works, but are there common problems with such a...
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    ESR meter - DIY - what do you think of this one?

    Thank you. One of the projects on that page is just the schematic, and the source is apparently gone, but wonderfully the web archive has it saved! https://web.archive.org/web/20101023201524/http://octopus.freeyellow.com/99.html I ended up building it, and it works great. He uses a 555 timer as...
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    ESR meter - DIY - what do you think of this one?

    Hello. I want to build this simple ESR meter. I was wondering what you guys think of it. https://electronics-diy.com/electronic_schematic.php?id=948 I especially wonder about it running at only 2.3kHz. Aren't we supposed to test capacitor ESR at around 100kHz? Would it be okay/necessary to...

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