555 simple electronic keyboard circuit

Published:2011/6/15 19:12:00 Author:TaoXi | Keyword: 555, simple, electronic keyboard | From:SeekIC

As the figure 14-40 shows, the controllable multivibrator is composed of the 555 and RA, RP1, C1, the oscillation frequency is related with the control voltage (pin-5), but the voltage of pin-5 depends on the partial voltage of R1～Rn and RB, and it is related with the conduction situation of VT1. The VT1 works in the amplifier region, voltage of electrode c is in the range of 3-6V, the control port pin-5 has a corresponding voltage value and it outputs the frequency of one scale or half scale. The lower the control voltage is, the higher the frequency is, but the control voltage is not less than 0.7V. When debugging, you need to adjust it repeatedly to distinguish the scales and notes. Any one of the resistors R1 ~ Rn can get the suitable resistance by using the series or parallel methods.



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