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Type: Posts; User: betwixt

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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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    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...
  7. Closed: Re: 80m phase shift SSB transceiver, How does it detect USB/LSB?

    I think it is DSB so no switching is needed.

    Brian.
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    Closed: Re: How can we send multiple bytes via UART?

    A UART can only send one byte at a time, some have a FIFO buffer that allows more than one byte to be queued for sending but the general principle is to load the first byte then monitor for the UART...
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    Closed: Re: The magical audio filter other opamps?

    I agree, and it will work better than a 741.
    The caveat with NE5532 and NE5534 devices is they have head-to-toe parallel diodes across the inverting and non-inverting inputs. That isn't a problem...
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    Closed: Re: Project using Opamps-intermediate level

    Suggestion: an analog calculator. One or two voltage inputs and one voltage output.

    You could implement add, subtract, multiply, divide and possibly log and square root functions by using op-amps...
  11. Closed: Re: Bootstrapping board for programming the ESP32

    I have attached the schematic for the ESP32 dev board. If you move the parts in the "Micro USB 5V&USB-UART" box to your bootstrap board and make connections of GND, TXD, RXD, EN and IO0 to your main...
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    Closed: Re: XMEGA UART TO RS485 problem

    RS485 uses only two wires and has a protocol for deciding which direction the bus information is traveling, it also specifies how devices in parallel on the bus are addressed so only one device at a...
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    Closed: Re: XMEGA UART TO RS485 problem

    You haven't enabled the MAX489!
    Tie '/RE' to ground and 'DE' to 5V to enable the receiver and transmitter circuits. You should ideally add a resistor of about 120 Ohm across the receiving end of...
  14. Closed: Re: HKTS 220 Power Supply board troubleshooting

    It could be. To be honest it is difficult to tell whether capacitors are working unless you monitor for residual signal across them. A good capacitor will charge on peaks of current and discharge on...
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    Closed: Re: Multi-loop antenna selector

    I didn't check accurately and you may be right but it is rather complicated and don't forget that regulators usually pass lower input voltages to some degree even if it is below the voltage needed to...
  16. Closed: Re: HKTS 220 Power Supply board troubleshooting

    Capacitors are the most likely cause. All the other parts have long lives but capacitors start to degrade from the day they are made, even if not used although if they are in use they degrade...
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    Closed: Re: Multi-loop antenna selector

    I wouldn't recommend that as a solution, it will work sequentially but not exclusively. It will add more loops as the voltage increases rather than allow individual selection. There would also be no...
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    Closed: Re: Multi-loop antenna selector

    Its really easy using MCUs but I know you don't like programming them.

    The simplest way is to get hold of two shift registers, one 'parallel in/serial out' and the other 'serial in/parallel out', ...
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    Closed: Re: Multi-loop antenna selector

    A simple summing amplifier is all you need, at it's simplest just join all the signals together!

    The phasing is exactly what you want, it gives the boost or cancellation essential for adding...
  20. Closed: Re: Bootstrapping board for programming the ESP32

    As the USB interface draws little current and will already have it's own protection at it's USB side connections, just draw power for it from the 5V and AMS1117. That is what most WROOM based modules...
  21. Closed: Re: Microcontrollers and a lot of advice - PIC , AVR, ARM - Software - Books - Boards

    You will find one of the strengths of C is its portability. Obviously some tasks rely on features present in particular processors but the 'glue' holding all the code together is standard from small...
  22. Closed: Re: Adding CCFL light or LED backlight to a 6 digit/7 segment LCD display

    I agree with Klaus. The contrast is largely dependent on the distance light passes through the polarizing layer and back again, if you remove the reflector it may not work at all.

    Try aiming an...
  23. Closed: Re: ZMR330: 3V3 Linear regulator needs diode connected cathode to input voltage?

    True - but it does say 'unconditionally stable' and the transient response graphs are labeled to say there is no output capacitor.

    I can't see any reference or requirement for a external diode...
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    Closed: Re: Multi-loop antenna selector

    You can try but I suspect the impedance matching of T3 stages in parallel might be a problem. 'Disconnecting' the bottom of R4 will still leave the B-E junctions of several T3's in parallel,...
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    Closed: Re: Multi-loop antenna selector

    Ideally you would use PIN diodes because they are optimized for good conduction and good isolation but there might, stressing that this would be very experimental, be a quick and dirty way to do this...
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