OT:48 Volt DC to 120 Ac Inverter-DIY?

[CJ]

Using a 48 volt battery power at home, I need an inverter for stuff that is to hard to convert to DC.
, figure that a 48 to 120 would be more efficient than tapping off a single battery.

I want to make an inverter that will put out about 2 or 3 amps at 120.

Have ferrite cores, mag wire, transistors, all I need is a schematic.

Any help greatly appreciated.

cj

 

[CJ]

Isd that it, way cool!

Must be secrets in the iron......

 

[PRR]

48V won't be fabulously more efficient than 12V.

If you just want something like 120VAC, the simple flip-flop buttachunk points to will "work".

I do not believe the author has tried this at the claimed 300W level. 2N3055 gain falls badly at 4A, and you have trouble getting 50W this way. Also I suspect R1 R2 eat a lot of power and fry. A 1,000W inverter is a much more impressive beast.

Output is Square Wave. You can tune the ratio for 160V Peak to power "120V rms Sine" DC rectifiers, or to 120V peak to power lamps, but NOT both types of loads at the same time.

If you are running batteries for low audio noise, this Square Wave is self defeating.

I know you are a DIY guy, but a computer UPS will give some simulation of a wall output, with a battery, and a charger, all in a pre-designed warrantied package.

The cheap UPSes are Square Wave. They do OK for PC power supplies, usually. They burn-up 120V lamps. They are incredibly nasty for audio.

Better UPSes use a step-wave which gives your 160V peak for DC rectifiers, but has enough off-time that thermal loads (lamps) feel about 120V rms.

"True Sine" UPSes are expensive, and often the sine's flaws are still big audio hash.

To make a good clean SINE wave, use a 60Hz Sine oscillator and a big audio power amp. Since you have 48VDC, this will be a custom. A switch-mode audio amp is not a simple DIY job, I'd stick with linear which means ~~75% efficiency at best (lightly clipped). Given 48VDC you can make 15V sine AC, step-up to 120V. For 3A at 120V (360 Watts!), you need 24 Amps at 15V, or a 0.625 ohm load. Basically a 30 Watt 8 ohm amp, but the output and driver stage 13 times fatter.

Or to avoid needing an incredible coupling cap, two 48VDC amps in Bridge (watch the low DC resistance of a transformer), 30V 12 Amps output to step-up. Same number of output devices (lots).

Or use a 60VAC CT winding with a "vacuum tube push-pull" plan, except with sand-state.

Megawatt utility companies have spoiled us. Making "small" like 300W of good AC is NOT easy.

 

[beatpoet]

You could always go with magnetic inductance.

A speed regulated wheel with coils, basically.

Nice clean sine wave!

 

[CJ]

Thanks PRR and everybody!

I am going to go with a Frys 39.95 inverter for the computer, which only needs 1 amp for both monitor and brain, my lighting is already 12 VDC, so no 120 needed there, all I would have left to DIY 120 VAC would now therefore be to power the stereo and TV.

Can a Sony 27 inch run off an inverter since I think they have a switcher in there anyway, or would the hash get into the audio and video?

I will try an experiment when I get the inverter for the comp.

So with the comp running off the inverter, this drops my current requirement down for clean 120 VAC to about 3/4 amp for the stereo, since I do not crank it like the high school days, unless I'm drunk, and I don't drink much

So figure 1 amp @ 120 VAC for a little extra room, the audio amp would would perfect here, we had an osc driven AC source thru an solid state DIY amp, but it was real sensitive to overload and would blow up, so I think I am going to get a used Crown DC 150 and drive it with 60 cps Exar chip OSC, build a step up trans with a huge core, and I am done!

Will report back as soon as I buy all this stuff.

:thumb:

 

[JohnRoberts]

There might be a temptation to play with other than 60 Hz for DIY inverter. While AC motors might be unhappy, most other PS components might be happier. One trade off, hum shifts upward into more audible frequency band, but ripple voltage and flux density drops so who knows?

JR

 

[Gus]

http://en.wikipedia.org/wiki/Motor-generator

http://en.wikipedia.org/wiki/Rotary_converter

Maybe remove the gas engine from a portable generator and speed control a DC motor in its place. Yes lot of loses but might be fun.

 

[CJ]

DC motor, never even crossed my mind, and a small generator sounds cool.

John, 440 would be great, fits right into the music, and you would not need a strobe tuner, just tune up to the hum!

That might not be a bad idea. 440 hz studio, a first no doubt.

Name it 440 Ocean Blvd or something corny.

Would I have to re varnish all the pwr iron to keep lam rattle down at 440, wait, we want that, never mind.

 

[CJ]

While looking for inverter circuits, I came across this link for a DIY UPS system.

The UPS is kind of a joke, but there is a lot of cool battery info in the article:

http://www.dansdata.com/diyups.htm