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Recommendations for IC noob

Discussion in 'Power Electronics' started by Electro_Noob, Aug 12, 2021.

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  1. Electro_Noob

    Electro_Noob

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    Aug 12, 2021
    I'm trying to design a micro circuit to use in model railroading. The package needs to be as small as I can possibly design it. The prototypes one and only job will be to control output to a single 0402 led.
    I'm not very familiar with ICs other than the 555 timer. I have a lot of input voltage range to play with, all the way up to 16vdc. I was hoping to get some professional input on what type of IC, if any. Could control a single LED, and is addressable allowing custom settings like flash rate, and being able to set differing high and low times. I don't know if it would be called this or not, but. I guess I could say I want to build a basic micro, digital LED controller. Only using the bare essential components, to save footprint size of the entire circuit. I just don't know ICs good enough to know if there is one that could do this and if so, which one it would be. thanks for any help
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    What do you mean by "addressable", and why only 0402 LEDs, you'll need to be more specific.
    Do you have any programming experience?

    Making things smaller is not necessarily any easier, in fact it can entail more work on your part.
    Reason being, most microcontrollers will come on a pre-built board often referred to as a module.

    In these the simplist are Arduino ProMini, follwed by ATtiny85 as a couple of examples.
    Masses of info and schematics and code available for the former, not so much with the latter.

    Your 16V dc is way too high for any micro, however, there are voltage drop down modules or even linear regulators easily available to get down to the required levels, and at such small current requirements, no problems.

    Electrical noise from the trains on the same supply could be though.

    Finally, there are also masses of sites dedicated to model railway electronics which might save you a lot of problems.
     
    Last edited: Aug 13, 2021
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  3. Bluejets

    Bluejets

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    Oct 5, 2014
    It is well within the scope of a 555 timer to do what you quote above though through the use of a couple of potentiometers on the 555.
     
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  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Have a look at ATtiny devices (example). Comes with a USART for communication (allowing for addressability) and TIMER (allowing brightness control via pwm).

    Or have a look at addressable LEDs like WS2812B. Addressable, RGB, 5 V operation. Effects like blinking need to be added by the external controller by turning the LEDs on or off. Libraries for using these LEDs with e.g. Arduino based controllers are readily available, as are tutorials on how to use them.
    This is probably the smallest all in one solution you can get.
     
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  5. Electro_Noob

    Electro_Noob

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    Aug 12, 2021
    Well, I'm going to be using this for N scale, 1:160, extremely small. I operate using DCC digital command control, track power is constant AC in the area of 15vac. I'm using smt components, I have a rectified, converted and filtered voltage of 3vdc down from 16va which I did last night. I can use a 555 ic along with a cap and a couple resistors to get a track powered led flash. But, I can't get the flash rate I need. I have played with the value of the resistors and the capacitor. But, I always end up with the led high and low time being the same. My goal is to get an on time in the milliseconds range and an off time in the 2 second range. And I say addressable because I'm used to working with DCC sytems. I should've said, configurable flash rate I guess. But wouldn't matter if I could just hard wire the flash rate I need into the circuit. I used this site, because I hope to learn more about the subject in general. From ppl who are more knowledgeable on design, application and component availibility, etc.. And, thanks to all of you for responding to my post, I know it's frustrating dealing with someone like myself.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    The WS2812 is not suitable for that purpose.
    Most unusual. The standard 555 timer creates a 50 % duty cycle only with tricks.
    There are many online calculators for 555 timer chips.
    Using e.g. this calculator and these input values.
    frequency = 0.5 Hz
    duty cycle = 0.05
    Caoacitor C1 = 1000 nF
    I get reasonable values for the resistors:
    R1 = 2883 kΩ
    R2 = 1.44 kΩ
    The duty cycle you request (on in ms vs. off in s) makes the resistances so widely different.
    Use these values as starting values to achieve the exact timing you need.
    You can use this simulator to see the result of your design. Note that the LED here is from the 555's output to GND, thus it is on for most of the time and blinks off for a few ms. Connect the LED from the output to Vcc instead to get the inverse result: off for most of the time with a short blip in the ms range for on.
     
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  7. Electro_Noob

    Electro_Noob

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    Aug 12, 2021
    thanks a million for doing all of this to help me out @Harald Kapp , and thanks for the resource links, I'll definitely breadboard and simulate this, this evening and share the results that I get!
     
  8. Bluejets

    Bluejets

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    Oct 5, 2014
    Unless you are using the cmos version of the 555, 3v dc will not be enough.
    Assume typo error "16va"......
     
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