something like this: http://www.hobbytron.net/functionsub.html ?
i think there are a bunch of $5 cheap ICs (which these kits are based on) which do exactly what you want
can't find a link but a web search should reveal more eg http://www.mitedu.freeserve.co.uk/Circuits/Testgear/funcgen.htm
i think there are a bunch of $5 cheap ICs (which these kits are based on) which do exactly what you want
can't find a link but a web search should reveal more eg http://www.mitedu.freeserve.co.uk/Circuits/Testgear/funcgen.htm
the data sheet doesn't show the schmidt trigger oscillator that gives near 50% duty cycle without having to change multiple resistor values in the "normal" astable oscillator circuit - tie thres and trig inputs together with a resistor/pot to output, and a cap to gnd from the inputs; to cover 3 decades of freq it is a good idea to switch in different C values
the schmidt trigger oscillator will be within a few % of 50% duty cycle, for better symmetry the classic solution is to use a digital divide by 2 flip-flop such as a 74HC74 on the oscillator output to get good symmetry and very square corners - the 74 AC74 can give ~ 50 ohm output Z as well
the schmidt trigger oscillator will be within a few % of 50% duty cycle, for better symmetry the classic solution is to use a digital divide by 2 flip-flop such as a 74HC74 on the oscillator output to get good symmetry and very square corners - the 74 AC74 can give ~ 50 ohm output Z as well
Maybe I need some edumactin'
If you made an oscillator with a 555 chip, wouldn't you just get a pulsed DC? The negative part of the square wave would be a period of zero volts and no electrons flowing in the negative direction.
Is there some device that would discharge some stored energy and cause electrons to go back in the other direction and create a true square wave?
Just wondering,
Aud_Mot
If you made an oscillator with a 555 chip, wouldn't you just get a pulsed DC? The negative part of the square wave would be a period of zero volts and no electrons flowing in the negative direction.
Is there some device that would discharge some stored energy and cause electrons to go back in the other direction and create a true square wave?
Just wondering,
Aud_Mot
Re: Maybe I need some edumactin'
YES! We call such a device a “Capacitor”
Hook up a 47uF capacitor to the output of the 555 and a 10k resistor to gnd. If you use a potmeter for the resistor you have a volume control as well. You can best use a C-Mos 555 like the TLC555. These are a bit faster and due to the higher input impedances are better suited to low frequencies.
Cheers
Aud_Mot said:
YES! We call such a device a “Capacitor”
Hook up a 47uF capacitor to the output of the 555 and a 10k resistor to gnd. If you use a potmeter for the resistor you have a volume control as well. You can best use a C-Mos 555 like the TLC555. These are a bit faster and due to the higher input impedances are better suited to low frequencies.
Cheers
This one will do the trick with just a PSU, two resistors (for tuneablility substitute one of them by a pot) and a capacitor added:
http://www.national.com/ds/CD/CD4020BC.pdf
=> look at the 4060 on this datasheet
Regards
Charles
http://www.national.com/ds/CD/CD4020BC.pdf
=> look at the 4060 on this datasheet
Regards
Charles
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