12VDC  to 28VAC  400 Hz  Sine Wave - Page 1
Forum section: electronics / projects

author: Ramjet555
author_rank: Newbie
timestamp: March 24, 2024, 09:55:00 pm
content: I'd appreciate some direction on building a 12 or 24v DC to 115VAC 400 Hz Sine Wave inverterI've got an experiemental aircraft and I'm putting in an Artificial Horizon that I was told was 28V DC but is not.It originally was in a SkyHawk fighter where 115VAC at 400 Hz was used because the transfomers weighed lessand it allowed more power on smaller cables.Any help direction will be greatfully appreciated.My email is this username at Gmail.com

author: Benta
author_rank: Super Contributor
timestamp: March 24, 2024, 10:13:57 pm
content: Any idea how much current or power it needs?Might be somewhere else on the labels.

author: Zero999
author_rank: Super Contributor
timestamp: March 24, 2024, 10:19:04 pm
content: Buy one?I found this on eBay.https://www.ebay.co.uk/itm/275442017671There's also this which gives 24VAC 400Hz, so would require a transformer, which could be an ordinary mains transformer run in reverse.https://www.powerstream.com/inv-12dc-24vac.htm

author: moffy
author_rank: Super Contributor
timestamp: March 24, 2024, 10:25:47 pm
content: You could use an audio amp ic of suitable power driven by a 400Hz sine wave to then drive , as Zero999 suggested, into a reversed mains transformer.

author: Ramjet555
author_rank: Newbie
timestamp: March 24, 2024, 10:29:09 pm
content: It says 115VAC 400HZ 1 PH what ever 1 PH means. I'm told it needs several ampsOne post for a similar different make said 3.5 amps.so far, I've learned that I will probably need to wind a toroid transformer for itand that a normal 50Hz transformer is not suitable.Pehaps another reader will know how much power this AH draws at 115VAC 400 Hz Sinewave

author: MathWizard
author_rank: Super Contributor
timestamp: March 24, 2024, 10:29:41 pm
content: So was the original VAC from some spinning generator ? 1PH is probably 1 phase, so just 1 sine wave

author: Zero999
author_rank: Super Contributor
timestamp: March 24, 2024, 10:35:11 pm
content: Yes, 1 PH means single phase.An ordinary mains transformer will work find at 400Hz.I have no idea about the power consumption. 3.5A would be over 400VA and is too much for any of the inverters I've linked to in my previous post. It does sound a low for something which weighs 2.4lb, which is just over half a kilo.

author: Benta
author_rank: Super Contributor
timestamp: March 24, 2024, 11:00:20 pm
content: OP, could you paste pics of the rest of the labels? I detect connection schematics that might help.

author: Ramjet555
author_rank: Newbie
timestamp: March 24, 2024, 11:09:15 pm
content: Sorry, there are no other circuit diagrams other than the picture I posted.It needs 115VAC at 4000 Hz at 3.5 amps Single Phase.I'm hoping for circuit or a kit for a similar aircraft instrument

author: soldar
author_rank: Super Contributor
timestamp: March 25, 2024, 12:10:26 am
content: Quote from: moffy on March 24, 2024, 10:25:47 pmYou need to be very careful because some amps can have problems with driving a highly inductive load.

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 26, 2024, 01:01:13 am
content: Quote from: Ramjet555 on March 24, 2024, 09:55:00 pmAs a fellow pilot, I will advise you to go to an avionics facility with your artificial horizon for help. Although you are courageous to fly an experimental anyway, mickey-mousing with avionics, especially your artificial horizon is dangerous. with non-standard electrical requirements you face a possible fire hazard while airborne.Also, an airworthiness certificate would not be forthcoming with compromised electrical/avionics systems and even if you obtained one, your insurance coverage would probably be invalidated if your log books showed a compromised and unapproved installation.A fire aloft is something you never want to experience. I was lucky years ago when I had a fire in the engine compartment which didn't penetrate the firewall as I may-dayed and dove quickly to an emergency landing.Just a thought.....

author: Ramjet555
author_rank: Newbie
timestamp: March 26, 2024, 11:58:35 am
content: Wow…If you read my post you would know that…It’s a Gyroplane, a RAF2000, home built, non certified,I work in an aircraft maintenance hangar, I have already asked local avionics people and it’s get a glass cockpit answer..It does not void insuranceI am just looking for a circuit to do12vdc to 400 hz single phase at 115v at an amp out

author: Andy Chee
author_rank: Super Contributor
timestamp: March 26, 2024, 01:26:08 pm
content: Do you have any size and/or weight constraints on the converter device?

author: CaptDon
author_rank: Super Contributor
timestamp: March 26, 2024, 01:46:24 pm
content: There is no way in hell that thing needs 3.5 amps even at startup!!! .25 amps is more like the truth. And yes, many aircraft generate 115v per phase and 200v phase to phase when coming from a 3 phase system. Nearly all turbine APU's are rated this way. So the load can be 115vac 400hz single phase or 115/200vac 400hz rated 3 phase generally for very high power devices like HVAC units and such. Your artificial horizon probably needs about 15 watts of power once up and spinning and maybe 30 watts or so at initial spin up. These devices get tested on 100 watt 400hz inverters. That 3.5 amps that you were quoted could be the 28vdc inverter input amperage for a fully loaded 100 watt inverter. Solid state inverters give a nice steady 400hz output. Mechanically driven 400hz alternators are a total crap shoot!! Anything from 360Hz to 440Hz is considered 400Hz! Consider the frequency shift when a turbine APU is suddenly asked to blow start the main engines. You may be able to find a pre-packaged 400hz 115vac avionic inverter in the 100 watt range. They commonly drove the gyro-compass and artificial horizon on 28vdc aircraft and often the pilot cluster had a separate inverter from the co-pilot cluster for obvious redundancy reasons.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 26, 2024, 01:48:39 pm
content: Isn't it easier to find a proper 28VDC-rated one than to add an inverter that is possibly larger than the device itself?

author: CaptDon
author_rank: Super Contributor
timestamp: March 26, 2024, 01:57:16 pm
content: B.T.W., on the homebuilt inverter idea. Almost any little 120vac to 12vac or 120vac to 24vac transformer rated at up to around 40va will work fine at 400Hz!! In fact they work well even at 1000Hz! A lot of the older test equipment that was 50/60Hz rated for the repair depots and used a transformer for the power supplies worked fantastically well at 400Hz!! And 400Hz is well within the range of the 1N4XXX series of rectifier diodes capability. (Probably not so for any dinosaur old enough to have selenium rectifiers) Oh, and just for fun, watch a 120vac 60Hz synchronis motor desk clock running on 400Hz!!! Time really does fly!! Cheers mate!! Blue Skies!!

author: CaptDon
author_rank: Super Contributor
timestamp: March 26, 2024, 02:09:28 pm
content: On the little aircraft the gyro and artificial horizon are air powered from engine vacuum or booster pumps. There may be some 12vdc versions around? Thinking 150's, 152's or maybe Traumahawks or Cherokees? There used to be a really nice aircraft salvage company in San Hose California. If they are still around they may have something for you? They were once a source for 28VDC jet engine starter/generators sought after by people making electric vehicle conversions hehehe electric Izettas, Ladas, Trabants and such!!

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 26, 2024, 02:22:54 pm
content: Quote from: Ramjet555 on March 26, 2024, 11:58:35 am1. Well, RamJet, I DID read your post(s) and I didn't see any reference to the type of aircraft that you now say is a Gyro-copter RAF2000 which, by the way has a checkered record from its development in South Africa to its lawsuits because of pilot deaths in the USA. so, Good Luck with that! I decided long ago that I wouldn't fly anything that didn't have WINGS so it could glide, not plummet.2. The glass cockpit is the RIGHT answer for your build of the kit-copter.: Modern, lightweight, low current draw, portability, multi-instrument display, GPS map, low cost, etc., etc. so, maybe pay a little more heed to the avionics folks, huh?3. I'm sorry that I cannot recommend or furnish you with an inverter circuit diagram that you could build or have built for you because it would eventually be going airborne and, you can say I'm spoiled rotten, but I'm a stickler for FAA-approval and compliance to approved and type-certificated products and processes even in the home-built and experimental categories and any circuit that I could provide would not meet those safety standards.I wish you the best regards in your flying endeavors, nevertheless. I'll close with my old quote for fellow pilots: "Remember, you can't pull over to the side of the road at 5,000 feet to fix a problem. Do it before takeoff!"Best,Major.