555 timer Tone Generator

Discussion in 'Circuit Help' started by DivadWaldoss, Nov 16, 2011.

  1. DivadWaldoss

    DivadWaldoss

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    I'm wanting to make a tone generator with a 555 timer that is a frequency humans can't hear. I'm going to follow the schematic below. My R1 (potentiometer) will be 10k. R2 will be 33k. C1 will be .001mF. What should capacitor 2 be? And would the resistors i mentioned work for making a tone within the 17-20 Khz range? Also, how and where would I attach the power source? I'm thinking about using a 9 volt battery. Or would something else work better? I want it to be able to run for several hours straight. Thanks!
    http://www.reconnsworld.com/audio_tonegenerate.html?
    or should I use a different schematic?

    If I have this completely off please let me know and guide me in the right direction. I'm new to this and would greatly appreciate any advice you may have.
    Thanks

    PS- I want it to be a constant tone, not a beap. Thanks
    DivadWaldoss, Nov 16, 2011
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  2. DivadWaldoss

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    C2 does not affect the frequency. Leave it as it is.

    C1 will be 0.001uF (not mF, 0.001mF = 1uF)

    To determine the frequency range, check with a 555 calculator. like this one.

    The circuit shown allows R1 to fall to zero. This is very bad. Place another 1k resistor in series with the pot and you'll be OK. Configured like this I get a frequency range of 110kHz to 480kHz. This suggests you really want C1 to be 0.01uF :)

    The top and bottom lines are the supply rail (they show the ground connection but not the other -- weird!).

    A 9V battery would be fine. The only problem is that the power consumed will be quite high owing to the 555 being used to drive a speaker directly.
    (*steve*), Nov 16, 2011
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  3. DivadWaldoss

    DivadWaldoss

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    Alright, so today i went to radio shack and bought myself a little birthday present. Let me know if it'll work or if i need to buy anything else. This is what I bought:

    555CN Timer IC
    10k- Ohm Audio-Taper Potentiometer
    10k 1/4 watt 5% tolerance resistors
    10k 1/2 watt 5% tolerance resistors (accidently bought this instead of 1k...)
    33k 1/2 warr 5% tolerance resistors
    .001uF Ceramic-Disk Capacitor
    1.0uF Metalized-Film Capacitor (they didn't have 1.0uF ceramic)

    I then obviously already have a 9v battery and clip. I'm going to salvage an on/off switch from an old electronic device.
    Can I use these parts to make what I'm wanting? If I need something else, please let me know! Thanks!

    also, i didn't have enough money on me at the time to get a board to put it on... is that a big deal? It's just an added expense and if it's not that important I'll just go without it... or do i NEED one?

    I was able to salvage a switch. I have a piezo speeker from a greeting sound card.
    so i have all the parts i need?
    so following this
    http://forum.allaboutcircuits.com/at...1&d=1258895992
    i dont use R1 or R2 since i'm not using LEDS
    where does C2 go? also, how do i know which resistors of mine to use to match with your schematic?
    would it help if i took pictures of what i have with labels, and have it layed out, then maybe you could tell me what to put where, or if you're feeling extra nice (after all it is my birthday, haha) make me a simple schematic using my parts.
    I really appreciate all the help!
    Thanks!
    DivadWaldoss, Nov 16, 2011
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  4. DivadWaldoss

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    I don't see a 0.01uF capacitor there, and there's no 1uF capacitor in that circuit (although it could be used in place of the 0.1uF cap specified for C2).

    An audio taper pot will change resistance very rapidly at one end. You should have got a linear one, but it this application it may not matter.

    I would have grabbed a breadboard to make up the circuit initially and to verify that it works. (also I'd start with C1 being 10 times the size so that the output is an audible frequency before changing to the smaller one). I say this on the basis that I am sure you don't own an oscilloscope.

    The pezo speaker from a greeting card should be fine, and will have a high impedance so the current drain will be lower (although you should measure this (but I'd guess you don't have a multimeter?).

    You probably need to purchase 2 x 1k resistors as per my recommendations above.

    I have no idea what the 33k resistor is for.

    But the 555 is right!
    (*steve*), Nov 17, 2011
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  5. DivadWaldoss

    DivadWaldoss

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    i used a 555 frequency calculator
    to get a pitch around 18-19 it had a bunch of different possible resistors and capacitor combos... i chose the one with a .001uF Cap... a 10k resistor, and a 33k resistor
    http://totusterra.com/555timercalc.html
    i typed .1 for the seconds ( i want a continuous tone) and 19000 for the hz... i used the specs for the 7th option down.
    DivadWaldoss, Nov 17, 2011
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  6. DivadWaldoss

    DivadWaldoss

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    also (sorry for double post)
    couldn't i just attach the ends of the components by twisting them to make a temp. connection. I didn't have enough money when i went to buy a board. :/



    EDIT: is there an instant chat we could use so i could get quicker answers? Thanks
    DivadWaldoss, Nov 17, 2011
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  7. DivadWaldoss

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If we used a chat client nobody else could benefit from our discussion.

    You can't just wrap the wires together -- it won't work.

    OK, I see where you got the R and C values.

    The circuit you showed first and the one on that calculation page are different, but not in any really significant ways. You can probably dispense with C2 in both cases without any real problems.

    You really should get a solderless breadboard to wire up the circuit on for testing.

    And how will you know it's oscillating?

    For a final build, using matrix board is probably the cheapest option.

    Do you know the pin numbering on the 555? looking from the top, one end will have a semicircular or circular mark in the casing. With this end pointing up, the top left pin is 1, and the pins go 1, 2, 3, 4 down the left side, then across to 5 on the bottom right corner and then 678 up to the top right.
    (*steve*), Nov 17, 2011
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  8. DivadWaldoss

    DivadWaldoss

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    so C2 isn't needed?
    How much are bread boards, and do they have them at radio shack? The 555 timer has a diagram on the back showing what number each pin is.
    I want this to be as cheap as possible. Once i see that it works i can take it off the bread board and solder it, correct?
    Hopefully to know its working i can turn it down to a frequency i can hear, and then turn it up to a frequency I can't hear. I could also turn it all the way up and turn it on when my dog is in the room. If she reacts then i know it works i guess... and then shut it off right away... dont want to be mean to her...
    also, the switch i salvaged is a sliding switch... left is off right is on, and on the bottom it has 3 pins. How do i know what to connect to which pin? Thanks
    DivadWaldoss, Nov 17, 2011
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  9. DivadWaldoss

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Well, C2 is different in both circuits, and neither purpose is strictly required. Alternatively you could include both. But take the simplest approach first. :)

    Radio Shack is probably the most expensive place to get stuff, but it may be convenient. solderless breadboards are available for only a couple of dollars if you know where to shop, and I hope you didn't pay more than $1 for the 555 (maybe the packaging will have some value for you)

    yes, the solderless breadboards don't damage the components. You can pull them out and use them again and again (or put them in a more permanent form)

    the connections you need are probably the centre and one of the edge ones. If you can borrow a multimeter from someone you can use the resistance range to measure it and find out for sure. Another method is with a battery, a bulb and some wire -- see which connections turn the bulb on and off as you move the switch.
    (*steve*), Nov 17, 2011
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  10. DivadWaldoss

    DivadWaldoss

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    the 555 timer was $2 :/
    no other place to get them in my town though... and i kinda need to start working on it now... if i get it to work i'll order more online
    DivadWaldoss, Nov 17, 2011
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  11. DivadWaldoss

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    At least it wasn't $4.99 :)

    For small and urgent purchases, you have less choice.

    Let us know how you get on.
    (*steve*), Nov 17, 2011
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  12. DivadWaldoss

    DivadWaldoss

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    I definitely will. I'll have a lot of free time this weekend, and maybe i can stop and get a bread board tomorrow (maybe)
    Thanks for the help
    DivadWaldoss, Nov 17, 2011
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