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Type: Posts; User: betwixt

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  1. Closed: Re: Turn light by usin MOC3021/BT136 and TTP223 Module to turn on 220v lamp

    Schematic doesn't make sense I'm afraid - have another go at tracing it.

    WARNING - a touch sensor wired to a non-isolated 220V AC supply is a recipe for disaster. You do realize that the sensor...
  2. Closed: Re: Best microcontroller for WPA2 Enterprise connection?

    I've never tried it but I can't see any reason why the certificate can't be saved to an SD card. It is only a text file.
    This might give you some ideas:...
  3. Closed: Re: Best microcontroller for WPA2 Enterprise connection?

    I use WROOM32 modules with much larger memory in them than the basic processor. A WROOM32 with a spring socketed development board is a powerful tool to have. Do all the programming and debugging on...
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    Closed: Re: Room Temperature using MCU

    That depends entirely on the kind of motor and it's power requirements. Tell us more and we will try to help, at the moment we don't know anything about this oven, it could be a quartz crystal oven...
  5. Closed: Re: Best microcontroller for WPA2 Enterprise connection?

    Without knowing how much memory you actually need it's difficult to advise but you could consider ESP32 as an alternative to ESP8266. From the outside they are similar but ESP32 has more...
  6. Closed: Re: Why is single channel voltage data-logging so expensive? (£96)?

    There is a free version of the compiler I use but the full 'PRO' version only costs £50 and it has full debugging and simulation (digital and analog) built in.
    I think the free version can compile...
  7. Closed: Re: Why is single channel voltage data-logging so expensive? (£96)?

    I appreciate your honesty about the software but it really is VERY easy.

    1. configure the registers including setting the PWM rate.
    2. detect zero crossing
    3. delay. This would be 5mS for 50Hz...
  8. Closed: Re: Why is single channel voltage data-logging so expensive? (£96)?

    I'm not sure exactly what you are trying to record in the log but 'reading every 200uS and store the maximum one every second' after passing through a transformer and attenuator suggests you are just...
  9. Closed: Re: Need a equivalent for microcontroller SST89E516RD

    From the first paragraph of the data sheet:


    Brian.
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    Closed: Re: Emulating TTL with an MCU

    You are missing the point. The clock speed only determines how many instructions the 8088 can execute in a given time, the rest of the system has to comply with timing constraints which probably...
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    Closed: Re: Emulating TTL with an MCU

    Neazoi, there are two factors at play, one is the propagation delay (time between a transition or control change at the input reaching the output) and the other is the rise and fall time of the...
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    Closed: Re: Emulating TTL with an MCU

    If you mean the 74F573, 74F244 or 74F245 devices, yes in theory if you can find an MCU running at a few GHz clock rate.
    They are 'Fast' 74 series because very short propagation delays are necessary,...
  13. Closed: Re: Error amplifier's output is very low as it controls led driver (Op Amp output)

    Adding diodes will degrade temperature stability. If you are concerned about near-ground response, why not use a potential divider at the output and increase the amplifier gain to compensate.
    ...
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    Closed: Re: 8 bit LCD interfacing with PIC 18F4523

    Just a guess as I don't have any data sheets to hand at the moment - your 'lcd_init' sets the mode as the last step, it should probably be the first step.

    Brian.
  15. Closed: Re: Cheap RF 433.92MHz design, PCB track antenna, values of capacitors

    I would think the 'straight' antenna would work best. Try both but my 'gut' feeling is there is no advantage to the second design.

    Without a schematic it isn't possible to tell what the 'linear'...
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    Closed: Re: How often do surges happen on the mains?

    Zak28 & ArakelTheDragon, Treez is speaking of transients rather than the entire network rising by 20V RMS.

    Grounding will never stop transients on the power lines and the 'circuit braker board'...
  17. Closed: Re: Use of comparator for sampling repetitive waveforms

    The clue is in that line.

    A DAC produces a voltage which is then compared to the sample using a simple comparator, the output tells you whether the sample is above or below the DAC output. You...
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    Closed: Re: AD9834 DDS Function Generator

    https://www.analog.com/media/en/technical-documentation/data-sheets/ad9834.pdf

    First hit in Google!

    Brian.
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    Closed: Re: Detect Reverse Polarity of Coil

    I'm going to expand on what d123 stated.

    Add a similar coil in line (on the same axis) with the one you want to check. Apply a known signal to the similar coil and see what comes from the coil...
  20. Closed: Re: Cheap RF 433.92MHz design, PCB track antenna, values of capacitors

    The circuit is identical except for the component values. The 3pF capacitor is equivalent to the 'twist' capacitor I mentioned before.

    I would be inclined to use the design in post #17 but add...
  21. Closed: Re: measuring capacitance of isolated sphere capacitor

    By connecting the other meter probe to the other side of the capacitance (wherever that is). This is exactly the same scenario as the capacitor would see in real life, the charge is built up against...
  22. Closed: Re: Help Needed to repair a CRT + pictures and info about the problem.

    I would think it EXTREMELY unlikely to be the multi-function IC. The fault has all the hallmarks of a horizontal output stage failure. Remember that if the IC horizontal output signal was missing...
  23. [SOLVED]Closed: Re: MAX31856 how increase thermocouple ESD protection?

    Another important point: you are dealing with tiny voltages and high gain amplifiers. The voltage source must only be the thermocouple tip unless you compensate using cold junction offset as at the...
  24. Closed: Re: Cheap RF 433.92MHz design, PCB track antenna, values of capacitors

    These are an actual 433MHz sender from a remote doorbell unit.

    151644
    151645

    The transistor is an MPSH10 and the inductor dimensions are:
    internal gap 3mm
    track width 2.5mm
    length from 3pF...
  25. Closed: Re: Cheap RF 433.92MHz design, PCB track antenna, values of capacitors

    'doubling back' the trace so its direction reverses is usually a bad idea, at least on such a small board. There is a danger that the radiated EM field cancels itself and therefore has shorter...
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