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Type: Posts; User: iimagine

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  1. Closed: Re: Square wave generation without Microcontroller

    Sure it can be done without ICs but do you have the time and patience to assemble all this? It wont be cheaper for sure.
    This is only half the requirements; still need the 2 transistors latch on...
  2. Closed: Re: 5 Transistors Linear Triangle Wave Generator

    Right, well they are switches for charging and discharging arranged to act as constant current source, what i meant by no constant current was the conventional current mirror, 2 transistors...
  3. Closed: 5 Transistors Linear Triangle Wave Generator

    Thought I should share my latest design to get some feed back and suggestion.
    No constant current source/sink!
  4. Closed: Re: Analog electronics book with circuit explainations

    That is quite a bit overwhelming infos for a beginner dont you think? :-D
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    [SOLVED]Closed: Re: Engine Running Detector

    Just wanted to say, the circuit worked as expected. I built it on a perf board and installed it in my car. Added a 'relay on' LED as a charging indicator. My secondary were around 9V and there were...
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    [SOLVED]Closed: Re: Engine Running Detector

    Yes, this is another way of doing it, thanks for the idea but I don't think it would be simpler/easier than what I have. However, it would be an ideal input for a micro processor

    - - - Updated - -...
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    [SOLVED]Closed: Engine Running Detector

    I decided to install a dual battery system in my SUV since I have a spare battery laying around. I bought a PAC-80, 'battery isolator' they called it... Its just really is a solenoid/relay. I had it...
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    Closed: Re: Please help about transistor as switch

    Because the current through each transistor's collector is always the same when it is on or off.
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    Closed: Re: Please help about transistor as switch

    Interesting... but theres a lot of wasted power too turn off LEDs
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    Closed: Re: Please help about transistor as switch

    FvM has been right all along. For the circuit to work, you will need some base bias resistors, the value of each base resistor must be atleast 10 times the load resistor
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    Closed: Re: Please help about transistor as switch

    This circuit came out of a book? This is not a very good example of how to bias transistor as a switch...how do they explain R2?
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    Closed: Re: Please help about transistor as switch

    This could never be! Is this some kind of a joke? What kind of simulation software are you using? Forget about the other 2 transistor, just simulate one. See if you can manage to get it to turn...
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    Closed: Re: Please help about transistor as switch

    What seems to be the problem? Have you breadboarded the circuit? What do you mean by drawing...?

    PS: You can get rid of R1, it is not needed, just connect switch to ground
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    Closed: Re: Please help about transistor as switch

    The circuit should work as intended unless you have incorrectly wired them. Double check your wiring
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    Closed: [MOVED] PWM Color Organ Brightmess Control

    Here is a little project I have been working on, to control brightness level of a color organ through a PWM driver via a smoothed low pass freq to voltage RC filter. The results were nice, I have...
  16. Closed: Re: How to increase amplitude of output voltage from 100 m V to 1V

    And here is the square wave obtained after the 2nd stage. Both bias resistors used were 1Meg ohms. So bias resistor for the 2nd stage must be of 5-10x greater than the load resistor. Although in...
  17. Closed: Re: How to increase amplitude of output voltage from 100 m V to 1V

    While experimenting with my new design, which I mentioned uses this little circuit, I was able to obtained an amplified waveform at the output of stage 1. Input was generated from the audacity...
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    Closed: Re: Transistor switching

    Its pretty much voltage divider law. If the output voltage dropped to 2V then the input resistance of the 74151 mus be around 15k, hence Vout = R2/(R1 + R2) * Vin
    Since your collector resistor is...
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    Closed: Re: Transistor switching

    Because that mux is loading down the output, try a 220k across the output and the connection to the mux
  20. Closed: Re: How to increase amplitude of output voltage from 100 m V to 1V

    Try connecting a 1m ohms resistor across the output and the probe, measure both outputs. Maybe bad bjts? If you have extra, just swap and see
  21. Closed: Re: How this circuit work?It puzzled me a whole night...T T

    Even if this base current flow is large, Q4's emitter voltage, which is set a 3.3V will prevent Q4 from lowering its base voltage
  22. Closed: Re: How to increase amplitude of output voltage from 100 m V to 1V

    a pic of your output would help a lot to identify the problems
  23. Closed: Re: How this circuit work?It puzzled me a whole night...T T

    Because as soon as Q4 turns on, Q1 also turns on. The moment Q1 turned on, it sources 3.3V to the 3.3V rail, which the emitter of Q4 rest upon. So now Q4 base has to be at 3.3V + 0.7Vbe - 2Vce = ~...
  24. Closed: Re: How this circuit work?It puzzled me a whole night...T T

    Tunelabguy is correct, Q5's emitter wont drop, because its is fixed at 3.9V, it will always be on
  25. Closed: Re: How to increase amplitude of output voltage from 100 m V to 1V

    That circuit was a part of the project I'm working on, that's why its drew like that 8-)
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