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    Momentary switch to power ON a circuit

    The LMC555 timer does operate down to 1.5V, but key issue is getting power MOSFET to turn on at real low Vgs. Circuit in post #14 sims down to 3V, but has annoying power on transient to load and for very long delays not sharp turn off. @OP, what on time do you want ? Regards, Dana.
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    Momentary switch to power ON a circuit

    A little better sim : The initial phase is power up, then at 3 sec a switch pulse on. Regards, Dana.
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    Momentary switch to power ON a circuit

    Something like this ? Button goes across cap. Regards, Dana.
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    Momentary switch to power ON a circuit

    Of course low end micros these days are like OpAmps and Regulators, simple, low cost, and so much more flexible. And generally save board area, componefornt count, and more reliable due to lower component count. Youtube has a series of videos on 3 - 20 cent micros, quite capable actually, not...
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    Momentary switch to power ON a circuit

    Just for future reference you can do this in mBlock on a small micro, ATTINY85, with more accurate timing and flexibility of functionality, and debouce the switch as well : (I think this would work) mBlock takes your block program and generates Arduino code and can either program directly a...
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    Relay to open/close circuit

    So basically you want one relay, one switch to power laser, and its coil energized by another relay/switch that door closed energizes the main relay coil. Power >> Main Relay Contacts DPST >> Laser Power>> Switch to turn on SPST >> Door switch SPST >> Main Relay coil >> Power Regards, Dana.
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    When the engine starts, sound will come from the mp3 card, and when the engine stops, sound will come from another mp3 card.

    You can modify post #2 to add a simple melody to output on a pin by adding a series of these blocks : https://stemify.weebly.com/buzzer.html Regards, Dana.
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    When the engine starts, sound will come from the mp3 card, and when the engine stops, sound will come from another mp3 card.

    If you have a signal that gives you, for example, a rising edge when engine starts, and falling when it stops, should be easy using a Arduino Nano board (cheap) or an ATTINY85 to output a select/trigger/address to your speech board. Using mBlock to create program here is a start : mBlock...
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    Automatic electric bell using wifi

    Note at Tuniot website there are basic clkient server examples for templatys, here ios the server one that you can build from : http://easycoding.tn/tuniot/demos/code/ Regards, Dana.
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    Automatic electric bell using wifi

    ESP8266 or ESP32 and Tuniot. A general Tuniot example : https://www.electro-tech-online.com/articles/verizon-hotspot-remote-control.949/ To get at net time the blocks to use are : Tuniot does not have net time block specific, so one uses Arduino code example and using the Tuniot block...
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    LED 1 input 2 output

    One possibility using mBlock on a ATTINY85 or Arduino Nano board. Starting possibility : mBlock converts your block design to Arduino Code. Rough proto- Regards, Dana.
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    Replace with what?

    Schematic ?
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    A Little Help for Brainstorming Ideas

    You allowed to put reflective markers on floor, and just use a photocell to turn off/reverse motors ? Not elegant. Better yet a reflective line on a floor, but still not elegant. Or an attractive female to just pick it up and lug it to/from destination ? Regards, Dana.
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    A Little Help for Brainstorming Ideas

    I think Otaku you are on right track, but timer inaccuracy so poor I would be inclined to use a processor, Arduino, and a stepper motor as its accuracy would be helpful backing up. Or use two ultra sonic sensors one facing forward, the other backward, or one that can be rotated 180 degrees with...
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    need help identifying a transistor

    2SK244 FET ?
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    Wall wart readings

    One vote for junk. Or cut it open and repair (if its not potted). Regards, Dana.
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    What is the value of this resistor (or is it possibly not a resistor)?

    https://en.wikipedia.org/wiki/Electronic_color_code https://duckduckgo.com/?q=resistor+color+code&iax=images&ia=images
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    Microcontroller ClockCycle speed thing question

    A common method when programming in C is to look at the compiled assembly language listing, and count instructions and their cycles needed to get a handle on speed. This is of course not exact as as asynch processes, like ISRs, can interfere with the execution of a routine. This of course does...
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    How to use low voltage switch for 110V circuit

    "Normally" one wants an isolated interface, that is AC line V can never get to the contacts of the pressure switch or the fluid stream for human safety considerations. One could use a wireless approach, switching on battery power to the remote that operates the power relay. Or just use contacts...
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    Looking for an old Motorola IC OpAmp SC9533P (7308)

    Its got a heat spreader in lieu of 6 pins in the middle. a power opamp ? Might have been a stamp off part number for Grundig. Regards, Dana.
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