555 beep in bursts

[Pro_Grammar]

I'm trying make a non microcontroller circuit that gives about 5 quick beeps then roughly 1 second off, repeat. I'm running on 2 AAA batteries. I already have a bunch of cmos 555 on hand so was trying to make that work. I'm using a 3V active buzzer which is quite loud. I tried a few astable variations, the attached circuit with R1=1K (in series with variable resistor), R2=100K, C=10uF gave me the desired timing sequence but doesn't beep, just a steady on, 1 second off, repeat. What changes can I make to get the desired timing but with beeps.
Thanks,
Rich.

 

[danadak]

The mBlock solution, just takes a bypass cap on micro, and of
course the buzzer external and its interface if driver not in it.

The code on right generated from the blocks you did on left. Length of each tone burst
trivial to adjust in mBlock, and same for overall interburst delay and "quiet" off time. Of'
course if you want a button to turn on/off process, even trigger process with a V or other
trip input that is trivial.

Regards, Dana.

 

[Pro_Grammar]

Final Version https://tinyurl.com/2392zzyl

View attachment 145043

Thanks Tony but it isn't working for me. Is anybody else able to try this to confirm if it works. My highest non-polarized cap is 100nF. I tried susbstituting a 1uF and a .47uF polarized (don't have a .67uF). Output is a steady buzz no beeping nor pause. For clarification what is the trigger meant to be. I had mentioned in an earlier post no trigger was required.

 

[Tony Stewart]

Excellent simulation; what program do you use? I assume you add a 2nd 555 to create repetitive cycles?

I completely missed the 3 V requirement - right there in the 2nd sentence (!). A 74HC132 is rated for operation down to 2 V, and should work in the #18 schematic. You might have to change the FET to one with a logic-level type. Note that the gate pinouts are different from the CD4093. I added a note to the post.

ak

No, but the link should answer your question and no other components are needed. The plots should self-evident how it works. Astable clock + Reset to stop after 5 pulses.

Final Version https://tinyurl.com/2392zzyl again

#14 should also work.

 

[eTech]

So....did you ever try the circuit in post #14?

 

[AnalogKid]

No, but the link should answer your question and no other components are needed. The plots should self-evident how it works. Astable clock + Reset to stop after 5 pulses.

I think you misunderstood my question. I know how the circuit produces *one* burst of 5 cycles at power-on. I'm asking about how it repeats and produces a continuous string of 5-cycle bursts separated by gaps of no cycles. Don't you need a 2nd 555 circuit (or some other oscillator) to continuously trigger the one producing the bursts:

I'm trying make a non microcontroller circuit that gives about 5 quick beeps then roughly 1 second off, repeat.

ak

 

[Tony Stewart]

I think you misunderstood my question. I know how the circuit produces *one* burst of 5 cycles at power-on. I'm asking about how it repeats and produces a continuous string of 5-cycle bursts separated by gaps of no cycles. Don't you need a 2nd 555 circuit (or some other oscillator) to continuously trigger the one producing the bursts:



ak

Yes sorry I don't understand the question. I read that he only asked for 5 pulses after power on not repeating bursts of 5. Although the quick burst was generated by the active buzzer at some audio frequency was not defined in length and he wanted 1 second off. So I compromised for 50% on 50% off in five 1 second intervals. But if defined that too can be changed if specified.

Originally I was thinking of 2 timers, On, Off and one counter which later compromised to a 1 Hz Relaxation Osc with a 5 s reset.

 

[danadak]

@OP, would you prefer to burst sines ? Or complex sines (arbitrary) ? Melody
or tone selection a direct expression of urgency ?

What accuracy do you need for timing, tones and delays ? Environmental and
its influence on tones and delays ....?

Is this a one off ? Anything more in the design that would benefit doing it all
in one chip ? Target cost of design (cheap is not a value) ?


Regards, Dana.

 

[AnalogKid]

Here is the circuit from post #18, updated with a better chip and its different pinouts. Again, these are not normal NAND gates; they have Schmitt trigger inputs that are the key to how the oscillators work.

While the HC132 parts should work fine with the added output transistor, the AC parts are special. They have an output stage rated for a whopping 24 mA of current, both sourcing and sinking. In the CMOS world, that's a lot. Also, it is rated to deliver that current even at the lowest operating voltage, again, not normal. This should allow eliminating the external driver transistor, as shown.

In fact, if you eliminate U1C and D, and drive the beeper with the U1B output directly (with the other end of the beeper connected to Vcc), the datasheet says there will be an additional 0.1 V of drive to the beeper. This is because even in a part designed specifically with an extra-beefy output stage, the p-channel (pull-up) transistors still are not as good as the n-channel (pull-down) ones.

ak

 

[danadak]

Looked for a "real" spice model for that part, or for that matter any other schmidt
input, none to be found. That could handle T evaluation.

When you build that circuit throw a little heat on part and cap, and watch freq vary by
100% or more (my guestimate, based on Vth sensitivity to supply V). Do same by varying
supply V.

Also I did sim, and using 1 Meg as fdbk it would not start, due to leakage forcing too
great a shift in input V due to DC offset. 100K seemed fine.


Regards, Dana.

 

[AnalogKid]

What leakage?

The caps are ceramic or film, not electrolytic.

ak

 

[danadak]

From the 132 datasheet :

Regards, Dana.

 

[crutschow]

Here is the circuit from post #18, updated with a better chip and its different pinouts. Again, these are not normal NAND gates; they have Schmitt trigger inputs

Just note that the hysteresis can have significant unit-to-unit variations as shown below, so the RC timing components may have to be tweaked to get the desired times.

 

[Pro_Grammar]

Probably because your supply is 9V, not the 3V that the TS wants

So....did you ever try the circuit in post #14

@OP, would you prefer to burst sines ? Or complex sines (arbitrary) ? Melody
or tone selection a direct expression of urgency ?

What accuracy do you need for timing, tones and delays ? Environmental and
its influence on tones and delays ....?

Is this a one off ? Anything more in the design that would benefit doing it all
in one chip ? Target cost of design (cheap is not a value) ?


Regards, Dana.

I did mention in my original post that I was trying to get 5 beeps a break, then repeat so yes cycle should continue till power down. I wanted attention grabbing without annoyance which is why I didn't settle on the staright beeping astable. The pattern is not as important as the breaks in the monotous beeping. I do want it small and cheap. As I said before, programming the Attny85 isn't beyond me I don't really need building blocks to do it, I've done my share of writing code and programming standalone atmels with and without external crystal. Just rusty, but I explained in a previous post my reason for not going that route. I was about to try the circuit in post #14 (Thanks eTech) but realized based on it's number of components that it would merely be academic. I ordered the 74hc132D from Digikey last night. Will report back.

 

[Nigel Goodwin]

I did mention in my original post that I was trying to get 5 beeps a break, then repeat so yes cycle should continue till power down. I wanted attention grabbing without annoyance which is why I didn't settle on the staright beeping astable. The pattern is not as important as the breaks in the monotous beeping. I do want it small and cheap. As I said before, programming the Attny85 isn't beyond me I don't really need building blocks to do it, I've done my share of writing code and programming standalone atmels with and without external crystal. Just rusty, but I explained in a previous post my reason for not going that route. I was about to try the circuit in post #14 (Thanks eTech) but realized based on it's number of components that it would merely be academic. I ordered the 74hc132D from Digikey last night. Will report back.

I can't say I've ever seen any explanation for not using a micro-controller?, it's such an obvious solution, and will be FAR smaller and work FAR better than the hardware solutions. Particularly as you have programming experience.

Personally, I'd use an 8 pin PIC (probably the 12F1840), particularly as I have code that will play Nokia ring tones for the 12F1840 But in any case, the repeating 5 beeps requirement is trivial to do.

But either PIC or Atmel, you're talking an 8 pin DIL (or SM) chip and the piezo - nothing else - it couldn't get any smaller than that (unless you used a 6 pin SM PIC?). You could also quadruple the power simply by bridging the piezo across two I/O pins.

Programming wise, either program it in-circuit, or if it's a DIL version program it externally (a breadboard would do), and once finalised, solder it in the PCB - if you don't want a socket.

 

[Pro_Grammar]

I can't say I've ever seen any explanation for not using a micro-controller?, it's such an obvious solution, and will be FAR smaller and work FAR better than the hardware solutions. Particularly as you have programming experience.

Personally, I'd use an 8 pin PIC (probably the 12F1840), particularly as I have code that will play Nokia ring tones for the 12F1840 But in any case, the repeating 5 beeps requirement is trivial to do.

But either PIC or Atmel, you're talking an 8 pin DIL (or SM) chip and the piezo - nothing else - it couldn't get any smaller than that (unless you used a 6 pin SM PIC?). You could also quadruple the power simply by bridging the piezo across two I/O pins.

Programming wise, either program it in-circuit, or if it's a DIL version program it externally (a breadboard would do), and once finalised, solder it in the PCB - if you don't want a socket.

Indeed Nigel if you're only programming one. If not then a no programming solution at a reasonable cost, if one is available will be more feasible.

 

[Nigel Goodwin]

Indeed Nigel if you're only programming one. If not then a no programming solution at a reasonable cost, if one is available will be more feasible.

Larger, more expensive, less effective - hardly more feasible

One or many, a microcontroller solution is the far better solution - and cost wise, you could always use an incredibly cheap Chinese processor instead of a PIC or AVR to make it even cheaper.

 

[Pro_Grammar]

Larger, more expensive, less effective - hardly more feasible

One or many, a microcontroller solution is the far better solution - and cost wise, you could always use an incredibly cheap Chinese processor instead of a PIC or AVR to make it even cheaper.

Nothing ends interest in a thread like an off topic eh Nigel. The brilliant minds here don't know me. They volunteer for both the help and the challenge. If the request in the original post for whatever reason is for a non-microcontroller option, an insistence in taking the thread in another direction is less about electronics and more about life. The internet is replete with double 555 circuits. My original attempt was to make the sole 555 work with "minimal additional components" (I neglected to mention that in my original post) and I presented that challenge to the gathering. Interestingly one of the earlier posts declared it impossible which apparently spurred a challenge. Invariably in a thread people will move away from the actual challenge because they're solution seekers. Helpful or not, that's a beautiful thing. Someone else may stumble across the thread and find purpose in it for something entirely different. Suggestion is also beautiful till it becomes insistent. Btw the circuit in post #6 does work on two aaa batteries but has a 3V input minimum. I appreciated the suggestion of the 2V minimum 74HC chip. I'll report back on testing after I receive that chip. Thanks to all contributors. Your efforts are appreciated.

 

[AnalogKid]

The circuit in #14 looks like it pulsating beeps for about 6 seconds, then goes completely off. Is that correct?

ak

 

[AnalogKid]

Referring to the #6 circuit, two things.

First, for both oscillators you should add a large value resistor from the R-C nodes to the left gate inputs. The reason is that the the capacitor is driven in a way that makes it a charge pump, and it applies a voltage to the left gate inputs that is greater than Vcc. This dumps capacitor charge into the transient protection diodes at the gate inputs, not a good thing. The same thing happens to the right gates, but the current is limited by the timing capacitor. Those input diodes actually contribute a significant error in the oscillator's frequency, calculated versus actual. The rule of thumb for reducing this error is that the added resistor should be at least 10x the max value of the timing resistor.

Second, it looks like the second oscillator is driving a bare piezo element, not an integrated beeper. The circuit will produce a sound that is a continuous tone for a time, then off for the same time, then on again. It will not produce a group of beeps in a burst, then off for a time equal to the length of the burst, then another burst, etc.. This is apparent from the large difference in value between the two timing capacitors. The ratio of the two frequencies is 470:1, whereas you want something like 10:1 (on for five beep times, off for 5 beep times).

ak

 

[AnalogKid]

an insistence in taking the thread in another direction is less about electronics and more about life.

Hence, my tagline.