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Type: Posts; User: betwixt

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  1. Replies
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    Closed: Re: load sensing circuit/relay

    Situation understood.

    What you have to consider when using a series transformer is the voltage drop it adds to the wiring. For example, using a 12V output transformer to drive a 12V relay, it...
  2. Closed: Re: PIC18F micro controller to send and receive atcommand

    You should be able to use any UART driver library or write your own. The LOra module uses 115200 Bauds serial protocol so all you have to do is hook it up to the PIC TX and RX pins then configure...
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    Closed: Re: load sensing circuit/relay

    Sorry for the delay, I've been busy elsewhere over the past few days.

    I don't think you need a transformer and optocoupler, both provide isolation but you only need one. What I was proposing is...
  4. Closed: Re: HAM radio topic: EM based design of a 432 MHz high pass with 144 MHz rejection

    Thank you Volker. This is a simple to build but high performing filter that I'm sure many of us will find useful, even in non-contest situations.

    Brian.
    GW6BWX
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    Closed: Re: GND For Connector Shielding

    Why are they not ALL connected directly to ground anyway?

    Brian.
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    Closed: Re: Addressable speaker system

    I would suggest a far similar system: Keep the wiring as it is but instead of using PWM, use a simple two byte serial stream. Byte one to identify loudspeaker 0 through loudspeaker 255 and byte two...
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    Closed: Re: 230VAC PWM LED bulb dimmer

    A dimmable LED lamp means it has an internal control circuit that recognizes the shape of 'chopped' phase control signals or uses PWM derived from its own internal controller. It doesn't necessarily...
  8. [SOLVED]Closed: Re: MAX232 alternative with more lines in single package

    Almost all the MAX23x and MAX24x interfaces are multi-channel. I think the MAX240 range is your best bet, check the data sheets.
    The MAX245 has 10 receivers and 8 transmitters in one package.
    ...
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    Closed: Re: 230VAC PWM LED bulb dimmer

    Firstly, make sure the GU10 LED bulbs are truly dimmable. Most already have a switching current regulator in them which will interfere with the drive signal from your circuit.

    I think it is...
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    Closed: Re: LOG19WHD17 TV - Freeview?

    According to the specifications it has Freeview built in.

    Usually on models like that there is a menu option to select the input mode. "TV" refers to analog transmissions, you have to set it to...
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    Closed: Re: Wht is the purpose of this op amp

    Away from the remaining circuit it is difficult to be sure but the most likely reason is because R18 and C25 form a filter and without the high input impedance of the op-amp following it, the load...
  12. Closed: Re: Testing Amps on rewound microwave transformer

    If you mean this:
    It isn't correct. The RMS reading of the AC from the transformer will be fine but the DC range will not give an accurate result. It is accurate for steady DC voltages, such as...
  13. Closed: Re: Testing Amps on rewound microwave transformer

    What exactly are you trying to measure?
    You cannot measure the 'Amps' because that is what you take FROM the transformer, not what it will just give to you. However, if you intend to draw 'X' Amps...
  14. Closed: Re: Testing Amps on rewound microwave transformer

    Provided you have enough capability to provide the maximum current you need, that is true. Amps represent the load, all you have to do is make sure the source is capable of producing them safely.
    ...
  15. Closed: Re: Testing Amps on rewound microwave transformer

    You are not understanding how current ratings work.
    Firstly, take note of what FvM wrote in post #3, it will work but that kind of transformer is not optimal.

    A transformer produces voltage, not...
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    Closed: Re: load sensing circuit/relay

    In principle your design will work but it has some drawbacks, there is an easier way!

    The problems are that you drop some of the line voltage in the transformer primary and the voltage reaching...
  17. Closed: Re: Regulating temperature of mains connected heating element: Skipping mains half cy

    This is getting rather complicated and expensive. My initial thoughts if burst control is to be used is a triac fired with a ZCD opto-coupler, in turn fed from a comparator with the setting control...
  18. Closed: Re: Regulating temperature of mains connected heating element: Skipping mains half cy

    The offset would only occur on the start of a conduction cycle, if you use SCR/Triac switching it will turn itself off accurately anyway.

    Why use back-to-back power FETs when a triac is so much...
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    Closed: Re: Project using Opamps-intermediate level

    The inverters (NME0505 etc.) take DC in and produce DC out, they are very small, about 10mm x 15mm x 6mm and have four pins. The two output pins are electrically isolated from the two input pins. If...
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    Closed: Re: very simple and short inverter circuit

    It is your video so you should know!

    In truth, yes it will work but it will be very inefficient and the LED lamp will not light at full brightness.

    First problem: Stepping the voltage up by 145...
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    Closed: Re: Repair SMPS for cooktop

    It uses voltage monitoring and linear feedback.

    The principle is to convert the output voltage to a current through the opto-coupler LED. It could be done with a simple series resistor but it...
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    Closed: Re: Project using Opamps-intermediate level

    The easiest way to produce a FIXED negative supply is to use a commercial inverter module. There are many with 5V in and 5V out or with 12V in and 12V out. As the output is isolated from the input,...
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    Closed: Re: Repair SMPS for cooktop

    Without knowing the specification of the original opto it's difficult to know if your replacement was suitable. They are however, very reliable. Typically they degrade in CTR over long periods but...
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    [SOLVED]Closed: Re: BLE v5 dongle isn't working on Ubuntu

    The advert says it will not enumerate in HID mode, perhaps that is the problem. You might have to 're-flash' it with more suitable code for your application.

    If lsusb shows it as a CP210x device...
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    Closed: Re: Project using Opamps-intermediate level

    Simply use two potentiometers, both wired across 0V and supply. That way you have two independent variable voltages with only two components being used!

    Do be careful with the supply voltage for...
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