How do you convert DC to AC

[Moe the Electrician]

Hi first time im posting (new to this place)

Does anyone know a simple format of changing DC to AC, or does anyone know how I can find the block diagram for this?

 

[jiripolivka]

Wat you need is a rectifier. Now, depends on AC voltage, frequency and power level you want to convert.
Tell us more, possibilities are many.

- - - Updated - - -

Sorry,I misread. To convert DC to AC, you need an inverter. Again you should indicate the specifications, then we can try to offer a solution.

 

[Programmer1971]

Yes we would really need to know the requirements for the AC you need. What is the AC voltage needed, how well regulated must it be? What amount of current (milliamps or amps) will you need to provide? What will the AC frequency be - and how steady must it stay? Typical house power in the USA is 120volts AC, and has a frequency of 60 hertz. If you are trying to take a automotive power source of 12 volts dc and make a few hundred watts of house power 120vac - then you can just buy an INVERTER at many auto supply stores - matching the wattage needed for your load.
If you have need of learning the specifics of how to do the conversion, it gets bit more to explain. Obviously we need to alternate the current on and off between x volts positive and x volts negative, and do it at the rate you need to make the frequency desired, but its not just on and off you will likely need. Turning it on and off between two supplies will give you a very square waveform, and most modern AC power is a sinewave that gently transforms from plus to minus in a curve. The needs of such a converter really do depend on the use of the power. Whether it needs to operate a light bulb (which could use DC as is) or run a motorized device that needs better waveforms and the ability to handle a stronger surge in current - how it will be used makes a big difference it what a design would use. An electric drill might show it needs for example 1 amp of power. At 120 volts this would be 120 watts of power - but at startup this same drill might require more current to get spinning, and could pull more when you really load it down. A conversion circuit to produce 120 watts of power would likely not handle a drill as well as a light bulb.
There are many ways to do the conversion - and most will not be very efficient - so if you need for example 120 watts of AC power - you will expend more on the input side. Back to the example - a 120 watt output is 1 amp at 120 volts - but that would be 10 amps at 12 volts if the circuit was lossless. Practical design would say you should figure on a significant loss in conversion, so it might be requiring 12 to 14 amps at 12 volts to run that 120w load.
Please let the forum know what DC power you intend to use, and what type of device needs the AC power and someone here will point you to a closer solution. Also - if you would, is this just to learn with or a real world application?

I hope this helps give you some more ideas. There are many new products on the electronic parts market that are designed to do power conversions.

Programmer1971 - www.oldhackers.com

 

[newcomer1]

Search for 'inverter circuit' (it is the opposite of rectification).
You will get plenty of diagrams and calculations to carry on.

 

[--BawA--]

use full bridge rectifier to convert AC to DC,
if high frequency signal is intended for rectification , use ultrafast diode such as UF4007, etc , depending on your current requirement.




Regards

 

[Moe the Electrician]

Thanks for the replies, I have done AC to DC conversion before so I know mainly the important bits of it. But as for DC to AC I know absolutely nothing.

And what I am doing exactly is a project which involves keeping Birds away from a hazardous electrical facility plant and I am powering my power through self powering solar panel (Photovoltaic cells) where as the solar panel creates DC voltage (But I haven't done this yet So I HAVE NO VALUES) which then I will need to change the DC to AC all I know is birds find the frequency of 2KHz sensitive and that would scare them away. So I am not sure exactly what potential different (Voltage) is need at the moment I do not worry about that much I will take it into consideration in due time.

As for AC to DC the steps is quite simple from its block diagram

AC Voltage Input -> Transformer (Step down or step up) -> Rectifier -> Filter -> Regulator -> Output DC Voltage


As for DC to AC how will the block diagram look like?


or lets say 5 VDC convert to 240 VAC how would you do this?

 

[Audioguru]

Scare birds away with the frequency of 2kHz?? To make a 2kHz sound whistle?
Why do you want an output of 240VAC? To "zap" the birds that touch it? They need to contact two wires to feel 240VAC. But usually birds stand on only one wire.

 

[Moe the Electrician]

Scare birds away with the frequency of 2kHz?? To make a 2kHz sound whistle?
Why do you want an output of 240VAC? To "zap" the birds that touch it? They need to contact two wires to feel 240VAC. But usually birds stand on only one wire.

I'm a bit confused myself, :-? what I am trying to do is create a sound barrier at 2 KHz because birds find this frequency sensitive and they do not like it. And for the sake of animal rights people I cannot harm the birds so "zap the bird" is out of the picture

So I was thinking of having frequency tower which sends 2 KHz from 1 tower to another and have these towers self powered through Solar Panels because the region is a pretty warm desert region.

If the towers are self powered through Solar panels then its known that solar panels creates Direct Current so then I taught in order to achieve the 2KHz with whatever Voltage value I will need to change the DC to AC right?

As I stated I do not have any value at the moment so I said 240 VAC as an example. I do not known have a potential different value at the moment (Voltage).

I looked into the suggestion that had been suggested to me to look into and search for "Inverter circuit" I found out from that, that PWM is used. I do not know what PWM is but I know that PWM is Pulse Width Modulation and it is used in Communication Engineering in making sounds. And PWM measures different points of waveform in either on or off and literally one will be able to create an analogue signal from it. Thats all I know in regards to PWM.

What is the block diagram for DC to AC?


Just like AC to DC is very simple to understand but DC to AC I have just never done it before

 

[Moe the Electrician]

Or maybe all I need to make is 2kHz sound whistle?

 

[Audioguru]

If you use an ordinary loudspeaker then rain and humidity will ruin it. Some speakers are weatherproof but if they continuously produce a tone then they do not last long.
Maybe let a weatherproof speaker produce a 2kHz beep for a short duration a few times per second? Then it will last for a long time.

The speaker is driven from an audio power amplifier. The amplifier is fed from a 2kHz oscillator circuit. Both are powered by solar cells and a battery.

You need to know how loud you want the beep and the maximum distance, which determines the speaker and amplifier power ratings and the DC voltage required.

 

[Moe the Electrician]

If you use an ordinary loudspeaker then rain and humidity will ruin it. Some speakers are weatherproof but if they continuously produce a tone then they do not last long.
Maybe let a weatherproof speaker produce a 2kHz beep for a short duration a few times per second? Then it will last for a long time.

The speaker is driven from an audio power amplifier. The amplifier is fed from a 2kHz oscillator circuit. Both are powered by solar cells and a battery.

You need to know how loud you want the beep and the maximum distance, which determines the speaker and amplifier power ratings and the DC voltage required.

Thank you for the help you made it a lot simpler

I need the beep to be constantly at 2kHz for a distance of 11,000 Meters 11km. So how would that determine the DC Voltage required and the amplifier power ratings?

what formulas are used?

 

[newcomer1]

You do not need to convert everything to DC. There are oscillators that can produce signal of different frequencies. The concept is simple: there is thermal noise everywhere (unless something is cooled down to 0K or -273celcius). The noise has all the frequencies but a tuned amplifier (with a feedback) will pick one frequency and sustain it. You can design one yourself on a bread board with op-amp or buy tunable ones. Then connect it to a speaker (add an pre-amp).

As Audioguru said, you should drive it intermittently so, you might like to multiply the continuous signal with some square pulses. You can build a 1-0-1-0 pulse generator using 555 IC and then use an AND gate IC to to drive the final op.

It would be like:

(2K signal Gen) x (1-0-1-0 pulses from 555) --->Audio Amp --> Speaker

It would be convenient if you mentioned what you are willing to do in the first post. That would save all the answers that other members typed to help you.

 

[jiripolivka]

To keep things simple:
1. Start with the DC output from the solar battery, measure the loading response(measure output voltage while loading the battery with various resistors).
2. Make a 2 kHz pulse generator and a power amplifier. I used a 555 timer with an IRF 530 MOSFET output stage, with an output transformer, both powered from 12 V DC (any voltage from 5 to 15 V can be used)
3. Find a ceramic beeper module tuned to 2 kHz. Those used in alarms are most efficient and give a nice annoying sound off.

You will, however find that the 2 kHz sound is quite annoying to people, not only birds. Another 555 timer can be used to pulse the sound by 0.5...2 Hz.
4. Add a suitable rechargeable battery (voltage set to an average solar battery output under load),to bridge cloudy sky. If possible, modify the DC power source around the battery, with an optional AC power source and solar battery, connected through voltage regulators (to protect the battery).

 

[Audioguru]

11km is much too far to send 2kHz. I live about 11km from an international airport and when a huge jet has its ass pointing in my direction and is at full power then I can hear rumbling low frequencies, not the high frequency parts of the sound.
Very large and expensive speakers are used at a sports event and play with hundreds of Watts for a distance of only 200m at most. The distance is only 1/55th the distance you want.

Start with a very loud sound of 120dB at 1m. It is 114dB at 2m, 108dB at 4m, 102dB at 8m, 96dB at 16m, 90dB at 32m, 84dB at 32m and is not loud at only 78dB at 64m. Wind and humidity also affect 2kHz.

To go 11km you will need hundreds of high power expensive tweeters, hundreds of expensive amplifiers and solar power cannot be used to power it all.