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    Arduino

    I would advise one look at the following : 1) The interval between two interrupts is NOT exactly deterministic. In instruction count or time. Depends on everything from other operations and in some newer high performance parts what is the pipeline, stack operations, shared busses doing. 2)...
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    Analog Devices releases Arduino offerings

    Will be interesting to see if they stay the course in support and development. So many vendors, over past 60 years, dabble in hobbyist/one off market, and discover there is no real money in it, and abandon the support.
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    Minimize Ripple in Rectifier by Waveform, Polarity, Bridge-Type, Inductor, Trafo?

    I know you stated no regulator but they have high ripple rejection (representative part) : Caps, for bulk caps Polymer Tants excellent (OS-CON is Polymer) : Pay particular attention to allowed C ESR specs in datasheets, if present. Newer types, especially LDOs, have min ESR requirements...
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    Multiple 5v relays inline

    Overkill on current rating but should be OK. This should be interface (ignore MOSFET part number). Note change the 100K from gate to ground with 10K. To minimize effects of noise pickup at gate thru parasitic C coupling. Regards, Dana.
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    Multiple 5v relays inline

    One correction to the earlier post, since you need to drive ~ 450 mA, a 2N3904, 2N2222 not adequate as the base drive to get the transistor is ~ 45 mA, too much for the MCU GPIO pin. Either use a logic level MOSFET (preferred) or a darlington TIP type transistor, either in a TO220 type package...
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    Multiple 5v relays inline

    See the DC current in the previous post ratings ? And the logic level specs on a pin - You have to switch the one relay with something like this - Diode 1N4007 or equiv. Transistor 2N3904, 2N2222.......
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    Multiple 5v relays inline

    You have to read datasheets and their pin ratings to succeed at designs. From the data sheet look at pin and max allowed current in the MCU supply rail ratings :
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    Multiple 5v relays inline

    This is correct way to wire these for operation off 5V. Your nominal current is ~90 mA / relay, so 450 mA required by supply. What exactly is the supply, eg. schematic ? Note there should not be an inrush current per se as they are inductive in nature, question is are they low Q so current...
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    Can you help designing buffer?

    Another useful building technique is "Manhattan Style". https://www.qsl.net/g4usp/HF%20SSB%20CW%20RX%202/Construction%20Techniques/HG-MANHAT2.pdf Regards, Dana.
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    CPLD

    Schematic, clock rates, etc.....?
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    Old board schematics

    Some solder problems : Bottom pin 2'ond one in from left. Top right pin. Top right 3 pins. Pics of top of board ?
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    logitech usb microcontroller

    You can always delid the part and get a part number off the die..... An early cost driving manufacturer with USB is/was Cypress PSOC 1 family. Now owned by Infineon. You could look at the package, find a drawing of pinout, and use a scope to see if its pin activity seems to match circuit...
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    Transformer overvoltage

    LM317HV (60 volts) - https://www.digikey.com/en/products/filter/power-management-pmic/voltage-regulators-linear-low-drop-out-ldo-regulators/699?s=N4IgTCBcDaIDYFsDMBGA7ACwG4gLoF8g https://www.ti.com/product/LM317HV?keyMatch=LM317HV&tisearch=universal_search&usecase=GPN-ALT Regards, Dana.
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    Can you help designing buffer?

    Lots of help here : https://www.youtube.com/results?search_query=stripboard Regards, Dana.
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    Can a faulty power supply cause random reboots in a computer?

    I just repaired mine, it collected a lot of dust, cat hair, and I removed old CPU thermal grease and added new. 2'ond time I have done this over ~ 10 years. Note used air compressor to blow out cpu heat sink, PC power supply, and motherboard. You can also log at windows logs for possible...
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    Building a low-cost wireless IR temperature multisensor data logging system

    Skysquid, I am retired, enjoying it immensely. So I will decline job offer. That being said there are quite a few consultants that can tackle your requirements. You might post over at Seed Studio website as they are immensely involved in the wireless parts I mentioned. Regards, Dana.
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    Building a low-cost wireless IR temperature multisensor data logging system

    Melexis makes a line of wireless IR T sensors, analog or digital I2C output. ESP32 makes life easy to get web page interface. Youtube a number of videos. Here is what it takes (~ 5 min max getting server up and running, eg. the coding : Tuniot channel : https://www.youtube.com/@ADELKASSAH...
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    Adruino connection question

    Which Arduino board are you using ? Max Vin to a pin dependent on that : https://en.wikipedia.org/wiki/List_of_Arduino_boards_and_compatible_systems https://community.element14.com/products/arduino/w/documents/3002/arduino-comparison-chart-boards-modules...
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    Help with led for aquarium

    Nominal 3 leds / string = 10.5 V, so for nominal 12V power the constant current supply needs to be compliant at 1.5V. Erode all these numbers, tolerances, T effects, LED threshold...and its a challenge with such a low voltage. A cure is just 2 leds / string, or raise power supply input V. You...
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    Temperature Control using DHT11 and arduino

    Correction to program, pin high to tun on fan, low off, I had inverted in if statements.
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