12vdc 700a IN 16.5vac .5 a OUT Need To Build

so, ye have a input power of 12*700 W and what to conver all that power in just a few 16.5*0.5W?

go for the second choice, my advice!

Err, this seems to be a terribly inefficient way to get 16.5V ac @ 1/2 an amp by starting at 12vdc @ 700Amps.

Maybe what you would like to try is using a buck/boost simple switcher (LM2577 or LMR6204 or similar) to boost the 12Vdc to around 18Vdc, then use that output voltage as a supply rail on an H bridge driven by a NE555 operating as an astable oscillator (pick your frequency). The output could be adjusted to provide you with the required 16.5vac.

You haven't mentioned how stable it has to be or whether it can be square or sine wave, nor what target frequency.

Or You could try this circuit just delete the rectification in the output.

http://www.simple-electronics.com/2009/09/555-timer-project-6-12v-dc-dc-boost.ht

Use a non cmos 555 timer, you will need to fiddle with circuit to provide the output you want

Sine wave 60hz.

It sound like you might have something there.

See this ? The board I have, can be run with this type of

plug-in transformer. This plug has 120vac in and 16.5vac out. I want to do the same thing only starting with 12vdc. the output has to be pretty close to the same when developed by by the input of 12vdc. But I only need .5 to 1 AMP

Do you know if there are any schematics? That page does not exist you mentioned.

If I understand you correctly you have a 12VDC power source that is capable of providing 700 amperes if needed. You wish to produce 16.5 VAC capable of providing 0.5 amperes out. You definitely need some more details here to proceed. To start with what frequency or range of frequencies for your AC voltage? Will this be a fixed 50 Hz, 60 Hz, span the nominal audio frequency range of 20 Hz to 20 kHz or is this into the radio frequency range. The voltage and current level that you request imply to me that you will be driving a nominal 8 ohm speaker. So a nominal automobile amplifier will likely be a good choice.

You understand quite well . 60 hz

Plug-In Transformer 16.5VAC/40VA, 120VAC

See this ? The board I have, can be run with this type of

plug-in transformer. This plug has 120vac in and 16.5vac out. I want to do the same thing only starting with 12vdc. the output has to be pretty close to the same when developed by by the input of 12vdc. But I only need .5 to 1 AMP

Have any Ideas?

My thoughts exactly. This has to be the most natural way to go about it.

Talk about over complicating a simple requirement.

Hey Wal,

It would be the most natural way if "your" life was run on 12vdc. and needed 110vac.

I did design a digital gas pump metering system, with power supply included, optic sensors, and scr power cut-offs and reset controls for $65.00 in parts, displayed pumps running, when selected, on 1 display( inputs multiplexed ). Chevron was selling theirs for $20,000 at the time.

Get it. I am not overcomplicating things

I can't find commercially what I need and am not to familiar with IC designs anymore to see what family to look into, or use for this circuit to do what I need.

"Guru's" shouldn't be so dismissive in their answers. Or just start using "DUH !"

there are a few devices, once used in VCR´s that easily convert a continuous current in a alternate courrent- with apreciable power out! you could have them in poli-phasic mode as well

If this is to power some widget board, the first thing I would do is check out the power input on your board. It may be the first thing the 16.5VAC goes through is a full-wave rectifier, converting the AC to full-wave DC. If that is the case, you would be able to bypass any conversion to AC, which greatly simplifies your task. If this is the case, post the details, and we can come up with a simpler solution to your problem.

Tom D.

Thank you for the thought .

It does rectify to 12vdc, but "senses" the AC input and reports trouble when no ac is present. So unless I can get the processor code re-written. I need AC on the input. The board works perfect, with 12vdc tapped in after the on board power supply. ( while reporting "trouble")

I do not want to convert 12vdc to 110vac and plug in 110vac transformer that has an output of 16.5vac because of all the power used during the conversion. The current commercial products are geared for higher amperage out ( ie-power loss for such a low power need, as I have) The conservation of power is quite critical.

Thank you again!

I have exhausted all the simple solutions I could think of.

These postings of asking for help are new to me. I haven't designed many things latley and was hoping technology had already exceeded the resolution to any thought I might have.

"I do not want to convert 12vdc to 110vac and plug in 110vac transformer that has an output of 16.5vac because of all the power used during the conversion. "

You said you have 700 amps available... those losses are inconsequential.

those losses are inconsequential?

Not in the use of the supply.

It is used for many other things that require lots of power.

The installation of my board that I need to run, needs 1 wire pair 18ga. as I see it.

If I am looking for outlets, and mounting locations that might not be conducive or obstructive, to install the converter and transformer. I will have a smile on my face.

And I can say my (.35a max) board and (??a) supply are a very nominal addition to the power being used in this unit.

I am serious about the car audio amplifier application. You can find complete DIY kits or just schematics with a simple Google search. Just adding a simple 60 Hz oscillator (Colpitts?) to the input of the amplifier and bingo your entire supply conundrum is solved. I'm bothered with your insistence for efficiency when your supply availability is so large. If your power budget is so tight on a 8400W supply that 80W cannot be allocated for this circuitry to get 40W available then there are considerable surge currents that must be considered in your design.

"... If your power budget is so tight on a 8400W supply that 80W cannot be allocated for this circuitry ..."

Wondering about that myself.

Marshall,
From the beginning you have provided the barest minimum of information, offering up a tiny bit more after someone asks pertinent questions. Then, you dismiss our suggestions because we assume too much about your requirements.

For the data presented, Johny451's suggestion of a COTS inverter remains the most sensible solution. Surely your 700-2800 amp power source can survive the additional drain of what equates to a small light bulb. (If not, then I foresee bigger problems ahead.)

What is the on board power supply? Bridge rectifier and a filter?

If so then 12VDC will go straight through it with possibly tolerable voltage drop through the diodes.

Have you tried that yet?

How is the AC sensed?

When you say "The board I have ...", I presume you are referring to a circuit board, either DIY or purchased.

The vast majority of circuit boards run on DC, even when the original input voltage is AC. See tdesmit's post #14. A full-wave rectified 16.5VAC will commonly produce about 22VDC, or higher for very light loads. If you follow the two AC input leads on your board, they very likely lead to a 4-terminal device which is the diode bridge. the other two terminals of the bridge are the DC output, and they will normally be connected to a relatively large capacitor. Measure the DC voltage either at the diode bridge or at the capacitor, and you will know what voltage your board really needs. Then either follow the advice of post #14, or that of Andy Germany's post #7.

I think you need to be more careful with your units. A 12VDC supply capable of producing 700A of current could run a large 12V truck starter. I suspect you really meant 12VDC 700mA (milliAmperes).

Similarly, in your table of specifications (which looks very nice, BTW), you specify "Output Current (Amps)", but give a value of "40VA". 40VA normally means 40 Volt-Amps, or Watts (Power, not Current). A 40VA, 16.5V supply should be able to provide 40/16.5=2.4 Amps. That is certainly adequate for the 0.5-1Amp you say you need.

Please see reply postings to #14 and others.

I have no misconception of the supply and AMPS available. I did not want anyone to think I was confused, so the posting of 700 AMPS was to diminish the comments of people who thought I might not have enough power available to supply the board I need.

Actually at times I will probably be hooking up my board, when completed to 12VDC 2,800 Amp Supply. (I will put in an in-line fuse!)

Buy a DC to DC converter....Something like this maybe:-

http://www.thiecom.de/sdr120w.htm

Here is a good source for service, equipment, parts, and technical support.

http://www.dimensionengineering.com/products/anyvolt-micro

Altronix AL1012ULXPD16 16 Output Power Supply/Charger - 12VDC @ 10 amp, fused no

0.0 0 $301.14 - $414.65 16 Output Power Supply/Charger - 12VDC @ 10 amp, fused non-power limited outputs, AC & battery monitoring, encl. 15.5?H x 12?W x 4.5?D, 115VAC input, UL Listed (UL294), cUL Listed

http://www.acopian.com/?src=msn

http://circuitpowersupply.blogspot.com/2009/12/12-vdc-to-120-vac-inverter-circuit.html#

Thanks for all the help. If anyone is still talking to me? I am going to try to modify this circuit.

Please take a look!

The 555 seems to be the simplest and easy. just need to find an appropriate T1 transformer. without building it I think I need a 1:1.5 ratio.

Thank you all again!

Any thoughts drop me a line.

Marshall - Yesterday at 6:00am we started the day at 96 degrees.

Hells kitchen, Arizona

New AC Adaptor Power Supply For HME AC40 Battery Charger Output 16VAC 2.5A 40VA | eBay

Given those figures, the input is oversized by a factor just under 100.

Perhaps that's why it cannot be found.

The oversize factor is closer to 1000. The input was probably 700mA.