Hello I have need for a timer that would be used to turn a 12 v. beeper device on for one second or less and then off for 10- 30 seconds and then back to beeper , looked at a bunch of 555 IC circuits and hate to spend a day experimenting to get the right combo. , as an old HAM , I used to love the challenge , even looked at using a timed relay , most of the 555 circuits are 50/50 and that won't do , any ideas would be appreciated . Phil L.
A good idea would be to read the datasheet, e.g. this one:
Then take a look at the schematic at page 9 and the formulas at page 10 for the duty cycle.
For more flexibility and one-chip solutions (you'll need two 555s for your application) you can use a microcontroller.
-- Frank Buss, fb@frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
That would be something like this: View in a fixed-width font such as Courier.
. . . . . . 12V . -------+------------------+--- . | | . | .---------+ . | | | . | | ------+----- . | | | Vcc | . [10k] '--|Rst | 1s . | | | - - . .----+-----------|Dis Out|--> | | | | . | | | | -- ---- -- . 1N914 v [270k] | | 28s . - | .--|Thresh | . | | | | | . '----+--------+--|Trig | . | | | . | .--|Ctl | . | | | | . 150u|+ 0.1u| | GND | . === === ------------ . 25WVDC| | | . | | | . -----+--------+----------+----- . com . .
A 556 would be a one-chip solution!
-- The Force is dark on one side, light on the other and holds the world together. Hmmm, just like Gaffer Tape then.
Yes, and maybe the cheapest solution, too, if you don't need more flexibility of a microcontroller. The advantage of a microcontroller would be that there are some chips with integrated oscillator, which means that you don't need any external component. The 556 solution needs many external resistors and capacitors.
-- Frank Buss, fb@frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
-- A 555 is a one chip solution. Did you not see Fred Bloggs\' contribution?
My understanding of the OP was, that he needs to generate the square wave for the beeper, too.
-- Frank Buss, fb@frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
--- There is no need for a 556, and the slick 555 solution needs exactly one 555, two resistors, one capacitor, and one diode.
The µC solution you propose needs one µC, one device programmer and, depending on how smart one is, a more or less huge effort required to climb the learning curve the first time out.
Also, note that Fred Bloggs posted a circuit which will work when assembled with the components shown while you haven't even offered a suitable µC or posted code which would do the job.
-- JF
One 555 would do it as there seems to be no requirement to toggle the beeper device.
However there seems to be a requirement to control the OFF time.
So a pot would be nice addition.
Also, the 12V beeper is most likely a high current device.
I also noticed that the OP has not chimed in yet.
donald
Right, well you can invert the duty cycle, parallel some 555 outputs, and add adjustment like so: View in a fixed-width font such as Courier.
. . . . . 12V . | . | . .----------+---------+-----------+------. . | | | | | . |_ .--|---------|--------. | ---+--- . \\/| | | | | | | 12V | . /500k | | ------+---555 | | | beeper| . /\\ | | | Vcc | | | | | . | | '--|Rst | | | ---+--- . | 1N914 | | | | | | . +-|>|---+-----|Dis Out|--+--|------' . | | | | . | | | | . [15k] .--|Thresh | | . | | | | 0.1u| . +----------+--|Trig | === . | | | | . | .--|Ctl | | . | | | | | . 100u|+ 0.1u| | GND | | . === === ------------ | . 16WVDC| | | | . | | | | . '----------+----------+----------' . com . . .
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