ben9 Posted December 30, 2005 Report Share Posted December 30, 2005 Hi, I'm from Colombia, actually, I'm a musician. I built a metronome using a 555 timer, and I'am very satisfied with the results. It works with a 12V DC supply, and works very well with batteries. The frequency of each beat is perfect, even when I use lower voltages. (I have tested it with 3.0 to 12V).For example, when I set it for 40 Beats Per Minute, every beat will be each 1500 milliseconds. (actually, it´s not digital, so I use a potentiometer to set the TEMPO).Nice. but I use the metronome with a Transformer or adaptor, conecting to an AC line, and I've found that there are some variatios in the period of each beat. for example: Setting it for 40 BPM, a beat can be at 1520 milliseconds, the otherone at 1505, etc. I mean, there is a variation in the period or frecuency. I think this happens because the DC out is not "CLEAN" I mean the AC is not well rectified. I installed an Electrolitic Capacitor of 2200uf after the bridge rectifier, and I got a little improvement. I installed a ceramic capacitor (0.01uf) between pins 1 and 8 (555's voltage supply) and another between pin 5 and ground, in order to get more stability. How can I to reduce this variation? how can I to get a better rectified DC output?. Thanks (please, excuse my english). have a happy new year!!! Quote Link to comment Share on other sites More sharing options...
EdwardM Posted December 30, 2005 Report Share Posted December 30, 2005 Hi Benthe fact that your circuit works happily with batteries means that there is nothing wrong with it. I suspect that the transformer/adaptor connected to the AC line is not capable of supplying the current needed to drive the speaker at a sensible volume.A couple of things to try...Use a (preferably analogue) multimeter in series with the batteries to measure current or -If you can borrow/obtain a power supply which has a current and voltage readout, you can verify how much current is needed at 12V, you will then be able to say if the adaptor is 'man-enough' to work.Hope that helpsEd Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 31, 2005 Report Share Posted December 31, 2005 I noticed that the polarity of C2 is backwards and it won't last very long.The output of the 555 is high most of the time.I agree with Edward that the 12V from the adapter is fluctuating with each beat. Using a 15VDC adapter with a 7812 regulator IC will fix it. ;D Quote Link to comment Share on other sites More sharing options...
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