I have a circuit design question. My controller output gives me a short pulse. I have a speaker that I would like to sound when that happens. Given that I have only one output available to me from the controller and the pulse is the only signal I get, what circuit could I use to work the speaker for a second? I could get a second controller, but that seems an overkill. Does such a circuit have a name? Delay circuit is close, but is not what I need.
Extended response circuit?
- Thread starter sjcomp
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Here is something for you to work on. A brief pulse will charge the capacitor C1 which will discharge slowly through R1. The Schmitt NAND (eg 4093) along with R2 & C2 form an oscillator which is gated on as long as C1 is charged. You need to play with the RC time constants to make it do what you want.
PaulStoffregen
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You could also use a 555 timer chip for the short pulse to trigger a longer pulse.
But perhaps what you want is the rising edge to trigger an oscillator, so the pulse results in a beep?
But perhaps what you want is the rising edge to trigger an oscillator, so the pulse results in a beep?
The NAND gate, along with R2 & C2 form an oscillator. It MUST be a Schmitt NAND for this to work. The diode followed by C1 & R1 extend the input pulse. This enables the oscillator. This is the kind of circuit used in simple logic probes - a very short pulse can make a 'beep' by switching on an oscillator
I'll take 1% of your first million
I'll take 1% of your first million
PaulStoffregen
Well-known member
Are you using a Teensy?
Why not just use the tone(pin, frequency, duration) function? It returns quickly, so your program is not stalled while the tone waveform is generated. You can specify the duration, so the tone will automatically end, which is perfect for quick beeps as audio feedback for a user interface.
With tone(), you only need a capacitor in series to block the DC voltage, and a 200 ohm (or higher) resistor to limit the current if a speaker is connected directly.
Why not just use the tone(pin, frequency, duration) function? It returns quickly, so your program is not stalled while the tone waveform is generated. You can specify the duration, so the tone will automatically end, which is perfect for quick beeps as audio feedback for a user interface.
With tone(), you only need a capacitor in series to block the DC voltage, and a 200 ohm (or higher) resistor to limit the current if a speaker is connected directly.
@sjcomp: I think if you want to operate your speaker for one second there is no need of controller, you can use the 555 timer as a mono stable multi vibrator to produce the one second pulse and the timing can be adjusted by changing the value of R and C i.e. Pulse duration=RC. Connect the output of your controller to pin 2 of 555 which is a trigger pulse that initiate mono stable multi vibrator and produce the 1 second output pulse.
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