Maker Pro
Maker Pro

Buzzer Circuit

electronicsLearner77

Jul 2, 2015
248
Joined
Jul 2, 2015
Messages
248
I have drawn the buzzer circuit, i still need to work out the resistance values, but on the high level is the circuit correct?
upload_2022-7-24_13-33-8.png
When the power to the buzzer is off, it will generate reverse voltage which will make the diode ON and discharge to ground. Is my explanation is correct? The other sections of the micro i have to populate.
 

bertus

Moderator
Nov 8, 2019
2,793
Joined
Nov 8, 2019
Messages
2,793
Hello,

Why do you want to power the buzzer via the 1K (R2) resistor?
Do you have the specifications of the buzzer?

Bertus
 

AnalogKid

Jun 10, 2015
2,688
Joined
Jun 10, 2015
Messages
2,688
The circuit concept as shown will work, but not very well. This is because when the buzzer is on, its current comes through R2. A better way is to eliminate R2, connect one end of the buzzer directly to Vcc, and connect the other end to the U2 collector. In this way, the transistor acts as a saturated switch. The impedance of the buzzer will limit the current through it to a safe value.
 

CircutScoper

Mar 29, 2022
300
Joined
Mar 29, 2022
Messages
300
The circuit concept as shown will work, but not very well. This is because when the buzzer is on, its current comes through R2. A better way is to eliminate R2, connect one end of the buzzer directly to Vcc, and connect the other end to the U2 collector. In this way, the transistor acts as a saturated switch. The impedance of the buzzer will limit the current through it to a safe value.

This topology might be even better. No need even for the diode, since the transistor will clamp negative excursions and protect itself.

temp.JPG
 

Attachments

  • temp.JPG
    temp.JPG
    19.2 KB · Views: 3

electronicsLearner77

Jul 2, 2015
248
Joined
Jul 2, 2015
Messages
248
This topology might be even better. No need even for the diode, since the transistor will clamp negative excursions and protect itself.
View attachment 55720
I will go through the circuit, but i have already did the following circuit.
upload_2022-7-24_19-59-28.png
I am not very much sure of the buzzer specifications, as of now i know it is 5V buzzer. I have also added the fan circuit which is other requirement, is it correct or do i need to add the diode for the fan circuit?
 

CircutScoper

Mar 29, 2022
300
Joined
Mar 29, 2022
Messages
300
I will go through the circuit, but i have already did the following circuit.
View attachment 55721
I am not very much sure of the buzzer specifications, as of now i know it is 5V buzzer. I have also added the fan circuit which is other requirement, is it correct or do i need to add the diode for the fan circuit?

If you want D1 to protect the transistor, its anode should connect to U3's collector -- not ground.
 

AnalogKid

Jun 10, 2015
2,688
Joined
Jun 10, 2015
Messages
2,688
This topology might be even better.
Disagree. As an emitter follower, U3 in your schematic decreases the voltage available to the buzzer by over 10% in a 5 v circuit, and by over 18% in a 3.3 V circuit. Besides the decrease in volume - if the "buzzer" is in fact a piezo beeper, that could be below its specified operating voltage range.
 

CircutScoper

Mar 29, 2022
300
Joined
Mar 29, 2022
Messages
300
Disagree. As an emitter follower, U3 in your schematic decreases the voltage available to the buzzer by over 10% in a 5 v circuit, and by over 18% in a 3.3 V circuit. Besides the decrease in volume - if the "buzzer" is in fact a piezo beeper, that could be below its specified operating voltage range.

True, although please recall I only said "might." Meanwhile, another truth is that, with no more info than the IP has provided about the buzzer and digital I/O, we don't know for sure that ANY external components are needed.

OC1 "might" happily drive the buzzer directly with no bipolar help at all.
 
Last edited:

Externet

Aug 24, 2009
854
Joined
Aug 24, 2009
Messages
854
The symbol shown is for a speaker; if it is a piezo element, it will want higher AC voltage and at resonant frequency.
 

CircutScoper

Mar 29, 2022
300
Joined
Mar 29, 2022
Messages
300
The symbol shown is for a speaker; if it is a piezo element, it will want higher AC voltage and at resonant frequency.

Good point. And if it's a naked piezo, then it will need drive for both polarities of the drive signal, therefore any driver consisting of only a naked transistor (e.g., mine) wouldn't work at all!
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,780
Joined
Jun 21, 2012
Messages
4,780
I think the Original Poster (OP), @electronicsLearner77, has presented us with an over-engineered "solution" to be "tweaked" and blessed.

The DSPIC33FJ32GS606 is a fairly sophisticated digital signal processor. Do you have an evaluation board with which to program and test its functionality?

The analog I/O ports have very limited source supply and drain capabilities. Operating things that require more than the 3.0V to 3.6V that the chip normally requires, should be done with the aid of an auxiliary circuit, as shown above for your fan and buzzer. However, instead of all the transistors, resistors, and diodes, consider using just miniature relays with a low-voltage coil, driven directly from the desired chip output. Be sure to include a reverse-connected diode across the coil to limit the back emf that occurs when the relay coil de-energizes. This diode will delay the release time of the relay to some extent, but should have no discernible effect on the operation of the fan or the buzzer.

We know the fan and buzzer must be just part of a larger project, but can you tell us why you require such a high-end controller/processor? Will you be programming it in a high-level language?
 

electronicsLearner77

Jul 2, 2015
248
Joined
Jul 2, 2015
Messages
248
We know the fan and buzzer must be just part of a larger project, but can you tell us why you require such a high-end controller/processor? Will you be programming it in a high-level language?
Yes i will be programming in C
The end application is variable frequency drive.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,780
Joined
Jun 21, 2012
Messages
4,780
Yes i will be programming in C
The end application is variable frequency drive.
Wow! You must be a fast @electronicsLearner77. I have been practicing electrical engineering "stuff" for quite awhile, although at a somewhat reduced pace now that I am "retired" and living in paradise. I wouldn't even consider designing, much less building, a variable frequency drive without a lot of help.

A few years ago I had an opportunity to become involved with life-cycle bearing tests on pressure lubricated high-temperature bearings. So we built a machine, a virtual copy of several that were in use at a lab at Wright-Patterson AFB, near Dayton, Ohio. We already had several employees vetted and cleared to work there, but management wanted closer participation "on campus" instead of several miles away. Hopefully this would give our company an "edge" in bidding on the next contract for this type of work. I don't know if that panned out or not, but we more or less copied their existing machines right down to specifying the same multi-phase motors and variable frequency controllers. These were not little motors, but I don't remember their horsepower rating or how fast they could accelerate and decelerate a shaft under load. Pretty Damn Quickly IIRC. And all this electronic equipment was made in Europe, not a single thing related to the motors was made in the USA. Why? Because the Air Force needed the bearing tests done ASAP and they already had test stands at WPAFB that worked just fine with the European components.

So, I got the job of seeing that everything was connected properly to our in-house three-phase 208vac wye power distribution. I got to put on my electrician hat and play "sparky" for awhile. This was a big break from chasing "virtual" leaks in high-vacuum chambers or coaxing high-energy ions from our ancient tandem particle accelerator. So I spent as much time as I dared reading the manuals (which were written in good English) and learning how to generate multi-phase, variable frequency power to drive motors. You never can tell when knowledge may come in handy!

I also learned that this was not new technology, and that there were several American companies who manufactured large variable-speed motors and variable frequency drives for them. Why didn't the Air Force use them instead of importing foreign technology? I suspect the main reasons were cost and time to delivery. Whoever bid and won the original contract did so because they promised, with some credibility, to deliver a working system on time and within budget. Whether that actually happened, I don't know. But there were at least a dozen identical test stands built and delivered to WPAFB. If several years later someone wanted more test stands built, that could be a huge problem. People move on, businesses change owners or try new directions. It may be impossible to create today what was built yesterday. Well, impossible without an exorbitant cost. The Government believes any problem can be solved if you can throw enough money and enough smart people at it. Take nuclear fusion for electrical power: that's always just around the next bend, about fifty years from now...

So, congratulations on your new project. I hope you are a member of a good team that appreciates your contribution.
 

CircutScoper

Mar 29, 2022
300
Joined
Mar 29, 2022
Messages
300
Wow! You must be a fast @electronicsLearner77. I have been practicing electrical engineering "stuff" for quite awhile, although at a somewhat reduced pace now that I am "retired" and living in paradise. I wouldn't even consider designing, much less building, a variable frequency drive without a lot of help.

A few years ago I had an opportunity to become involved with life-cycle bearing tests on pressure lubricated high-temperature bearings. So we built a machine, a virtual copy of several that were in use at a lab at Wright-Patterson AFB, near Dayton, Ohio. We already had several employees vetted and cleared to work there, but management wanted closer participation "on campus" instead of several miles away. Hopefully this would give our company an "edge" in bidding on the next contract for this type of work. I don't know if that panned out or not, but we more or less copied their existing machines right down to specifying the same multi-phase motors and variable frequency controllers. These were not little motors, but I don't remember their horsepower rating or how fast they could accelerate and decelerate a shaft under load. Pretty Damn Quickly IIRC. And all this electronic equipment was made in Europe, not a single thing related to the motors was made in the USA. Why? Because the Air Force needed the bearing tests done ASAP and they already had test stands at WPAFB that worked just fine with the European components.

So, I got the job of seeing that everything was connected properly to our in-house three-phase 208vac wye power distribution. I got to put on my electrician hat and play "sparky" for awhile. This was a big break from chasing "virtual" leaks in high-vacuum chambers or coaxing high-energy ions from our ancient tandem particle accelerator. So I spent as much time as I dared reading the manuals (which were written in good English) and learning how to generate multi-phase, variable frequency power to drive motors. You never can tell when knowledge may come in handy!

I also learned that this was not new technology, and that there were several American companies who manufactured large variable-speed motors and variable frequency drives for them. Why didn't the Air Force use them instead of importing foreign technology? I suspect the main reasons were cost and time to delivery. Whoever bid and won the original contract did so because they promised, with some credibility, to deliver a working system on time and within budget. Whether that actually happened, I don't know. But there were at least a dozen identical test stands built and delivered to WPAFB. If several years later someone wanted more test stands built, that could be a huge problem. People move on, businesses change owners or try new directions. It may be impossible to create today what was built yesterday. Well, impossible without an exorbitant cost. The Government believes any problem can be solved if you can throw enough money and enough smart people at it. Take nuclear fusion for electrical power: that's always just around the next bend, about fifty years from now...

So, congratulations on your new project. I hope you are a member of a good team that appreciates your contribution.

coaxing high-energy ions from our ancient tandem particle accelerator
Would that have been a tandem Van de Graaff? Many decades ago when an undergrad at CalTech, I designed and built beam-chopping circuitry for one under the Sloan/Bridge labs. It was used (IIRC) because of its ability to produce beams of very accurately controlled energy.
 
Last edited:

hevans1944

Hop - AC8NS
Jun 21, 2012
4,780
Joined
Jun 21, 2012
Messages
4,780
coaxing high-energy ions from our ancient tandem particle accelerator
Would that have been a tandem Van de Graaff? Many decades ago when an undergrad at CalTech, I designed and built beam-chopping circuitry for one under the Sloan/Bridge labs. It was used (IIRC) because of its ability to produce beams of very accurately controlled energy.
Well, yes, it was designed by Robert J. Van de Graaff, and others. And, yes, it was a tandem, a small heavy-ion research accelerator built in the 1950s by High Voltage Engineering Corporation, a company that eventually went out of business and whose designs were absorbed by High Voltage Engineering Europa. Their "compact" tandem accelerator was called a Tandetron. Mine was capable of 1.7 megavolts positive terminal potential (with respect to ground) on a good day.

Several of these machines still exist and, AFAIK, are in use today. If memory serves me correctly, it was a tandem, similar to the Tandetron, that was used to first demonstrate the use of an accelerator mass spectrometer for age-dating microgram sized specimens, including small snippets from the Turin Shroud. I investigated the cost to "upgrade" my tandem to perform accelerator mass spectrometry (you need to carefully separate isotopes and measure their relative quantities) and was told by someone "in the know" at National Electrostatic Corporation that it would cost more than a new machine bespoke for that purpose... which NEC would gladly build for me. At that time, the only job we had for the accelerator was oxygen-ion implantation into 5-inch GaAs wafers containing integrated-circuit semiconductors for device isolation in lieu of chemical etching. The Department of Defense helped us develop the isolation process at the Air Force Institute of Technology, located on the campus of Wright-Patterson AFB near Dayton, OH. So, no need to look for business dating ancient relics. The DoD customer sent me a box of twenty or so patterned wafers, coated with a layer of developed photo-resist, every month for several years. I loaded the wafers into a purpose-built wafer carousel and implanted ten or twelve different energies to obtain a uniform isolation depth between "devices" on the wafer. I never was told what the devices were, but they had to be pretty hot stuff to go to that much trouble to make them!

The High Voltage Engineering Corporation was founded in 1947 by three MIT graduates: Robert J. Van de Graaff, Denis M. Robinson, and John G. Trump. It was a well-designed solid-state (Cockroft-Walton) accelerator, and several models are still in use AFAIK. One, at Oak Ridge National Laboratories, was decommissioned when its operator took another job in Knoxville to make radioisotopes with a small cyclotron for PET scanners. Another was in use at a university in Kansas, but I forgot the name of the nice young fellow who inherited it. There was a very nice machine installed at the Ion Beam Laboratory in Ann Arbor operated by Dr. Ovidiu Toader. and another exists here in Florida near Orlando that was in the process of being moved to a different building the last time I talked with them before retiring in December 2014.

The problem with any tandem, my Tandetron included, was it requires negative ions to be accelerated first, stripped of some of their negative electrons, and then accelerated again as positive ions. Unfortunately negative ions are not easy to produce, and some elements do not produce a stable negative ion. National Electrostatic Corporation is the world renowned expert at building high-voltage tandems based on their Pelletron chain charging system. They built the now de-commissioned 25 MV Holifield Radioactive Ion Accelerator at Oak Ridge National Laboratories. You can find NEC pelletrons all over the world. They sponsor the international Symposium of North Eastern Accelerator Personnel (SNEAP) every year with hosts located around the world. SNEAP is an informal gathering of scientists and engineers who operate electrostatic particle accelerators for the purpose of exchanging operating notes, and procedures and to have a good time touring accelerator facilities and nearby "tourist type" attractions with their families. My wife and I have attended meetings at ORNL (twice) and once at the Michigan Ion Beam Laboratory near Ann Arbor, MI. We were especially impressed with our tour of the spallation neutron source at Oak Ridge and the superconducting RF accelerator at The National Superconducting Cyclotron Laboratory (NSCL) on the campus of Michigan University near East Lansing.

Eventually our DoD customer moved on to larger GaAs wafers, which we could not efficiently implant even if we extended our beam line to scan the larger area. Our tandem used a nitrogen gas stripper line, operating at very low pressure, to "knock off" two or more electrons from the accelerated negative ions, thus creating a positive ion for further acceleration by the positive terminal voltage. Unfortunately, the process was very inefficient so it was very difficult to obtain positive ions with more than +1 or +2 charge state. I needed the +2 charge state to reach the maximum required implant energy. On a really good day, I could get about one microampere of +2 charged oxygen ions, so a box of twenty or so wafers would take all day and a good part of the evening to complete. Still, it was steady and predictable work and I enjoyed it... mostly. In my "spare time" I was tasked with keeping the rest of the electronics equipment (including the high-vacuum systems) working. You would be amazed at what can go wrong when a scientist tries to operate 120 vac synchronous clock motors inside a vacuum vapor deposition chamber without the benefit of using an isolation transformer. And I never did get across the idea that you don't control the speed of such motors with a Variac. I don't miss that part of the job.

Hop -- AC8NS
 
Top