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  1. Replies
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    Closed: Re: OP amp output oscillating

    I've taken your valuable feedback into account and added low pass filter. Signal should be somewhat steady DC voltage but in vehicle use I guess there is many interference sources.
    150840

    What...
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    Closed: Re: OP amp output oscillating

    Thank you all for helping me. This might be just bit off topic, hopefully ok. Bear with me please. I decided to ditch the idea of LM2902 & relays etc. as it was possible to achieve what I was looking...
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    Closed: Re: OP amp output oscillating

    I terminated the not used op amp, but it didn't make any differences. Could it be then so that on breadboard this is not possible to make work?
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    Closed: Re: OP amp output oscillating

    Tried cap parallel to R3, no help. I added also cap to the ic supply pin, after taking this picture. Sorry, picture is huge for better visibility.
    150776

    0.049V starts oscillating. 0.054V stable....
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    Closed: Re: OP amp output oscillating

    I isolated the microcontroller and put only BC547 transistor which controls 30mA led. Still oscillating. It is the signal from the amplifying U1:A which is noisy. As I had extra OP amp available I...
  6. Closed: Re: LED light power supply fix recommendations

    Just found out that our national authority for electical safety has announced that this power source is dangerous and should be pulled off from sales. Great, not only that it is bad it is also...
  7. Closed: Re: LED light power supply fix recommendations

    Just fed from lab power limited 10V and 300mA current was limiting it and voltage was 9.05V so Vf 3V. Then with 350mA voltage was 9.13V. So I need to limit the current and this should work:...
  8. Closed: Re: LED light power supply fix recommendations

    I might have found the led type. Pretty certain that it is:
    https://www.cree.com/led-components/products/xlamp-leds-discrete/xlamp-xb-d

    Dimensions and outlook match. Print on that AL board XBD...
  9. Closed: LED light power supply fix recommendations

    Dear All,

    Bit over 3 years ago I bought four Trio Tiber outside LED wall lights which half of them have failed. First they started blinking and then went very dim. Opened one of them and the COB...
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    Closed: Re: OP amp output oscillating

    4MHz is the crystal frequency as well. It could be that crappy breadboard or jumper wires. I've already found few not conducting jumper wires..

    Voltages are created by Lab power which can go to...
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    Closed: Re: OP amp output oscillating

    It is noisy as well and oscillating.
    Here is the oscillating:
    150738

    Here is the noise:
    150739
  12. Replies
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    Closed: OP amp output oscillating

    Dear All,

    Here's my circuit
    150735

    When input voltage gets to 47mV LM358P OP AMP U1:A strengthens that voltage by 48 times and OP AMP U1:B compares it against reference voltage 2.18V and turns...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    Sorry, got bit confused. You mean maybe in some other case eg. PIC16F1847 which has TRISA and TRISB and if those are set "1 = PORTA pin configured as an input (tri-stated)" it needs resistor? In this...
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    Closed: Re: Short circuit protection in PCB design

    I came across PTC multi fuse. That seems like super simple and automatically resetting and no other components needed. Is that viable option? Only thing I noticed it has around ~2ohm resistance, but...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    Ok, that's no brainer. PIC datasheet says sink current is as well 25mA as source current so that's plenty for most transistor base currents..
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    May I borrow bit this same thread even though this is bit unrelated. Do you need pull down resistor for NPN transistor base when controlling it through PIC output? I'm pretty certain that the pic has...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    That's it! You're my hero. Thank you! Wohoo, now it's working.

    That leads me to one more guestion. Since day one I started with these PIC microcontrollers it has always been bit soft to me that...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    This is getting more confusing. ADC input pin GP0 is messing up things. If I plug that GP0 to VDD, GP1 is not oscillating anymore. If plugged to GND it does oscillate (or some other low voltage in...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    Added 10us delay after every output state change and all I could find is that the positive and negative width is now 10us longer. So I guess it's not RMW then...
    Also removed the break and changed...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    Thank you both for your input so far. Sorry in my first post I wrongly wrote GP3 on those oscilloscope texts. It should have been GP1.
    So GP1 is only output and that is doing that (can I call that...
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    [SOLVED]Closed: Re: PIC12F683 pin high problem

    You're correct, no need to convert the ADC reading to voltages, I could use as well the ADC readout directly. It just made it easier for me to undestand the voltage directly instead.. That part...
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    [SOLVED]Closed: PIC12F683 pin high problem

    Dear All,

    I'm once again turning to you with one issue that I'm not able to solve by my self. I'm using PIC12F683 which reads through ADC voltage and blinks led in various frequencies. That part...
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    Closed: Re: Short circuit protection in PCB design

    I decided to use the op amp and power resistor circuit from GreatScott example. Then that signal to PIC input. PIC will cut the current by small 5V relay. Actually I programmed it so that it will...
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    [SOLVED]Closed: Re: Amplifier Yamaha RX-V657 not turning on

    Wohoo, it's fixed! Just received my digikey order and changed Q404, IC, D404, D405 and D406 (previously C405). I'm pretty sure that Q404 as well as the C405 were broken. Q404 is now STD2HNK60Z-1...
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    Closed: Re: Short circuit protection in PCB design

    Ok, so I should ditch that so called short circuit protection schema.. I wonder why it actually worked on the breadboard. I understood that it diverts the current through the 10k resistor instead...
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