555 Timer

Discussion in 'General Electronics Chat' started by Coremeister, Jan 20, 2014.

  1. Coremeister

    Thread Starter New Member

    Jan 19, 2014
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    0
    I need some help with a circuit layout (or 2 ) for the following project.
    I would like to use 555 timers if possible as I have a few around from previous projects (if there is a better way then I can use whatever is the better option).
    The circuits need to run on 12 volt DC.
    I have had a look at some of the designs already provided on this site but none seem to be quite what I need, I could probably nest a few of the current circuits together to achieve what I need but I was hoping there is a simpler a more compact way of doing it.
    The circuits are only to run a couple of extra features in my Daughters Cubby House.
    The cubby house is fitted with a small kitchen that has a microwave and conventional oven as part of the unit, I have already fitted the microwave with a momentary action switch that triggers a timer to feed power to the LED controller that then powers a LED light strip that is inside the microwave, this flashes to produce a visual effect of something happening inside the microwave, when the time is up (approx. 15 to 20 seconds) a piezo emits a small beep to signal the end of the time. The oven does something similar except that it only flashes red and doesn't currently have a sound at the end of the time.
    I would like to create a new circuit or 2 that can do the following.
    The first circuit needs to be timer with a beep - beep - beep sound at the end of the time the circuit is on, this is to replicate a microwave, I would like the circuit to provide power to the RGB controller (only needs to switch the 12 volt +) I would like it to provide power for approx. 15 to 20 seconds (actual time is not critical) and then when the time is up produce the 3 beeps through a piezo speaker (if this is difficult or complex I already have a separate piezo that can be setup as a vehicle reversing beeper , if the circuit could provide power to this for a specific period of time I could adapt it to produce the required beeps, although I would prefer the circuit to produce the beeps through the already fitted piezo).
    The second circuit needs to do basically the same thing except at the end of the time I would like the circuit to produce a Ding - Dong (like a door bell) this would be for the oven section of the kitchen.
    If its easier for both circuits to be on the same board (maybe they could share some components) that may save some space or if its easier to have them separate, which ever is easier to construct would be fine. Each circuit is triggered by a separate momentary action switch so they could be independent of one another, if each circuit needed a separate piezo for the sound I can simply add another.
    As I only have a limited knowledge of these electronic parts i would like the circuits to be a simple as practical.
    If anyone has any ideas or could provide a circuit layout I would be much appreciative.

    Thanks

    Corey
     
  2. ian field

    Distinguished Member

    Oct 27, 2012
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    There's quite a few things you can put inside a microwave for lots of flashing and visual effect - but most of them don't keep doing it for long!
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,055
    The 15 second delay timing is an easy project and I would use a simple 555 timer circuit called a "one shot" or astable.

    Generating the sounds you want is another story, particularly the ding-dong. I think it would be easier to play a pre-recorded sound-on-a-chip. Maybe someone else has a better idea.
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    It's not a real microwave; it's a toy.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Ignoring parts values, look at the Vibrator Driver ckt as an outline for 3 beep sound effect. Add another 555 as a one shot timer to enable U 1. Re space D1 & D2, add a D3 for a 250 ms beep seperated by 750 ms for 3 beeps.
     
  6. Coremeister

    Thread Starter New Member

    Jan 19, 2014
    2
    0
    It is indeed a toy, if the LED lights that are flashing inside what is essentially a timber (MDF) box can manage to produce enough heat or radiation to make things flash I think I will have got something very wrong.
    Thanks for the advice so far, will try to get my head around the circuit suggested (could be a little complex for my basic knowledge), I may have to ask for some advice or explanations as I go, if that's ok.

    Thanks again

    Corey
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    A simpler ckt would use 3 555's, second gives a pulse & a seperation, first gives a longer pulse that encopases 3 or more pulses, & 3rd drives sounder.
    Bing- bong might be as simple but with 2 pulses, with the second pulse of a lower frequency. Or a complex sound generator, or prerecorded message.
    'Forgot the two predelays, add 2 more 555's.
     
    Last edited: Jan 21, 2014
  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Here is something to throw stones at: U1 provides the adjustable 20 sec delay & can drive a relay or semi conductor switch to control LED's. At timeout it starts the 3 beep cycle. If interested, I can supply more inf.
     
  9. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    There's a possibility of reducing the chip count by using a hex-inverter ring counter.

    You'd have to include some C/R delays to stop it whizzing round too fast to see, but I'm certain there's examples on the web.
     
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