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The 555 timer has been on my mind for the last month and I though that I’d make a simple tutorial on how to make a square wave tone generator using it.  It’s incredibly easy to find sources that give schematics of the process and cool ideas for its application and I thought I’d throw my two cents in the ring and help with some clarification and some links to further study.

To start this project (making a square wave tone generator) you only need a few bucks and some soldering skills.


-assortment of capacitors – get a good range, from smaller – .1uf – up to 10ufvarious parts

-assortment of resistors – getting one of those grab bags at Radio Shack can be expensive at first but will last you for a while

-assortment of variable resistors – photocells, 10k – 500k potentiometers (linear), heat sensors etc.

– obviously a few 555 timers – these can be found at any decent electronics store for around a buck a piece, or you could go online and get them for a few cents each.

– a solder-less breadboard, similar pre-coppered circuit board, or plain old perfboard.

– some jumper wires, solder, soldering iron.

– a couple LEDs… if you’re feeling crazy.

– a 9 volt battery and appropriate connecting cable

– an enclosure – box, shoe, sunglasses… whatever you want to mount the circuit onto… it’s incredibly small.

– a 12 pack of some cheep beer…pabst

1. Clean off your work space and make sure you have extra parts, I would also recomend getting a jumper wire kit for the breadboard… although it’s not neccesary, it makes things faster and easier.breadboard

2. set out your breadboard and make some contact between your hands and something metal to discharge anything that could fry the IC.

3. gently push the 555 timer into the breadboard – if you are going to make a link of two or more 555 timers then I would suggest placing the IC all the way right on the board.555 timer

4. connect pin 1 (GND) to ground and pin 8 (V+) to the lead strip on either side of the 1 and 8

5. Connect pin 2 (Trigger) to pin 6 (Threshold)

6. Connect pin 4 (Reset) to pin 8 (Positive voltage supply)pin 2 - 6 and 8=4

7. place a 10k resister between pin 8 and pin 7 (Timing regulated by cap discharge)10k resistor

8. Connect a variable resistor between pin 7 and pin 6 – you can use a photocell or a potentiometer here, I recommend using a larger photocell or a 500k pot. Now connect a .1uF capacitor between pins 1 and 2 – note the placement of the cap because you’ll be changing it out for other values later.hotocell

9. connect the tip from a jack to pin 3 (output) and the ground from a jack to the negative (Ground) side of the the power supply

10. connect the 9v battery to the positive and negative sides of the power supplyaudio and power

11. test the circuit without audio by placing an LED in between pins 3 and 4, anode towards pin 3LED test

12. if the LED lights up then turn on your amp and see if you’ve made any sound… if not than check your wiring, flip the LED around, or start over.

The range coming from this circuit will be medium- high and you can adjust the pitch with the variable resistor, try using a light bulb to effect the photocell, or adjust the pitch stably with the potentiometer.  experiment with larger value capacitors to find a good range for the frequency, the larger you go the slower and lower the range will be, so for really fat bass throw on a .22uF – 10uF cap.

The cool thing about this circuit is how easy it is to line up other 555 timers in a row and make amazing sounds… build two of the exact same circuits right next to eachother only this time use a 10uF cap on the first 555 timer circuit and a .1uF cap on the second, connect the two pin 3 outputs with standard diodes and see what happens. experiment with different variable resistors and light sources, or plug some LEDs between pin 3 and pin 4, notice how the pitch and frequency are effected… this is an amazing little chip and it holds so many different applications inside… I hope you start makeing some square waves soon.




  1. hey, im having some trouble with this. i can get the circuit to make sound, but only if i actually use my hands to bridge the connections between pins 6 and 7. any potentiometers i connect either dont make sound, smoke, or make very high frequencies, and any photocells i connect stop all sound regardless of light present. what am i doing wrong here?

    • Any way I can get a pic of your final product? What kind of pots/photocells are you using?

    • Do you have the potentiometer wired right?

      Is the photo cell working?

      If you are getting a really high frequency, you might need more resistance.

      Try putting some higher resistors in place of the pot just to test out the circuit.

      Good luck!

    • Do you have the positive terminal connected to pin 8? I’ll draw a schematic and post it soonish.

  2. 555 timers are fun.
    Lately I’ve playing with 556 ones.

    • Yeah! 556 timers are rad. I like your work, I have about 6 months of projects that I haven’t loaded up yet… I know, I neglect my blog, but I’ll get some fresh content up ASAP.

      • Yeah i know what you mean.
        I got a bunch of breadboards on my desk
        with all kinds of oscillators, sequencers and noise maker thingys.

        Need to make some time and get it all together.
        Including my blog.

  3. Nice tutorial. Simple and easy to follow.

    • thanks for checking it out

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  12. thank you for the tutorial. but what do I do with the beer?

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