555 timer tone generator ???

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
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try this:

+5v | .-[47K]-+----------+ | | . . . .|. . . . | | . VCC(8) . | | . . | `----RES(4) OUT(3)--------- out | . 555 . in -[100K]-+-------+----TH(6) DIS(7)----. | . . | +----TR(2) CV(5)--+ | | . . | | | . GND(1) . | | | . . . .|. . . . | | | | | | | 100n +--||----' | +---||-----+ 10n | | | | `--[10K]---)----------' | ---+-- gnd 0v ////// Increase the 47K to 51K to make it silent with Ov input, Bye. Jasen

I see how the timing cap charges positive, but how does it discharge?

I'm going to suggest a slight modification. Modified quoted text:

The "Out" signal will be a string of pulses. If you wire things up this way, the time the pulse is low for will be constant with respect to the input.

In the previous version, the pulse on the Out will get wider as the voltage increases.

In the modified version, the voltage vs frequency curve have a slope that gradually decreases when you get near the upper limit. In the unmodified version, the slope would decrease more rapidly and the frequency would eventually start to decrease.

Does this set up work on 14VDC Vcc?

Yes, the whole circuit scales up and down. If it makes "Y" Hz when the input is 5V and Vcc is 5V, it will now make "Y" Hz when the input is

14VDC.

The LM555 is rated at IIRC 18V. Check the data sheet of the actual model you are using. Look for the Absolute Maximum voltage and stay well below that.

^^^^ This guy ------------------

Through the 10K I marked.'