ET System AC Source EAC 500 - Page 1
Forum section: electronics / testgear

author: capt bullshot
author_rank: Super Contributor
timestamp: November 27, 2018, 10:27:49 am
content: Got that boxfrom the evil bay. Wonder what's inside an how to operate it though it doesn't have any controls and the RS232 port isn't working:Teardown and some reverse engineering:http://wunderkis.de/AC-Source-EAC/

author: Terry01
author_rank: Frequent Contributor
timestamp: November 27, 2018, 12:26:10 pm
content: I have no idea what it does or what it could even be for but it is very cool indeed! It'll be awesome if your able to fix it and get it working again and then tell us exactly what it is and how to operate it.It's funny how like I say "I have no idea at all what it is or what it does" but it really interests me to find out and see it working. I really hope your able to get this working again and put it to work somehow.

author: Berni
author_rank: Super Contributor
timestamp: November 27, 2018, 12:31:32 pm
content: That is quite the impressive pile of power electronics in there. So it is essentially a sinewave signal generator with a massive output amplifier?I wonder what application these things are used in given the 80V output range. Like driving coils to generate magnetic fields, or running some sort of large voice coil based mechanical actuators to really shake something properly?

author: capt bullshot
author_rank: Super Contributor
timestamp: November 27, 2018, 12:36:19 pm
content: Terry01: Sorry, didn't think of thatWhat is it: It's an AC source - that's the technical term for it.What does it in general: It outputs an AC voltage of selectable / variable frequency and amplitude. In particular, these units output typical voltages of 100V to 250V, at typical frequencies from 50Hz to 400Hz, with some respectable output power (this unit is specified for 500VA, one can get them in the range from 200VA to several kVA and three-phase models).So if you see the output specs, what does it in particular: It simulates an AC power supply (like your household mains) for testing purposes (e.g. of power supplies at different line voltages and frequencies). More advanced testing includes short voltage interruptions, sags, and harmonic content, you'd require an arbitrary waveform generator to do so with this unit, modern ones have that built-in.Just imagine a variac that isn't adjustable for output voltage only, but also for frequency (and more recent units also waveform) and doesn't depend on mains stability.And to anticipate: Yes it works, and I'm able to control it, but it's still work in progress. Updates will follow.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 27, 2018, 12:38:48 pm
content: Quote from: Berni on November 27, 2018, 12:31:32 pmYes it is.Something strange about it is the DC output range: -82V ... 82V but the AC range is 0V ... 260Vrms. So it's clearly a mains simulator as I wrote above. There's another of these boxes on the evil bay (don't know if it is still available), that has an 80V AC output range, for sure some kind of special purpose model as these usually are mains AC sources.

author: Berni
author_rank: Super Contributor
timestamp: November 27, 2018, 12:57:51 pm
content: Ah yes i have mistaken the 82V DC range as the total output range. Yeah indeed it is s mains simulator then. Id imagine they use it to test mains appliances and mains transformers for brownout, harmonics, DC offset etc.Since it has a good deal of sensing on the output would probably point to it being a power analyzer at the same time to give you things like apparent and real power, cos fi etc.If you don't get it working you can still just add a analog input BNC on it and use it as a gigantic amplifier.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 27, 2018, 01:25:39 pm
content: Quote from: Berni on November 27, 2018, 12:57:51 pmYes, the modern ones are supposed to include some kind of power analyzer capabilities. This one is old enough to just provide you with a reading of output frequency, voltage, current and maybe real power, that's what I can guess from the pictures of other units of the same breed.It's working without the CPU board, I can control it using some pots and switches and I'm able to use the external oscillator input also (that wasn't originally brought out, but it's there somewhere inside). My plan is to use an external analyzer together with it.

author: Terry01
author_rank: Frequent Contributor
timestamp: November 27, 2018, 04:28:26 pm
content: Quote from: capt bullshot on November 27, 2018, 12:36:19 pmCool, thanks for the explanation. I understand now what it is. I will be following along to see what you end up doing with it.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 27, 2018, 10:16:20 pm
content: Added a small update of how I got in control of it and did some testing.Same page (http://wunderkis.de/AC-Source-EAC/), just scroll down.

author: capt bullshot
author_rank: Super Contributor
timestamp: December 02, 2018, 05:04:33 pm
content: Another small update:I've put the switches and pots into an external control box, making the thing usable.http://wunderkis.de/AC-Source-EAC/Errata:In one of the diagrams I'd drawn, there's a block "More Rectifiers". Turned out these aren't rectifiers but some SSR (presumably) do to auto-ranging for the transformer secondaries. The secondaries are connected in parallel for output voltages up to 130V, and connected in series for higher voltages. So the full specified power can be delivered over the full output range without overloading the transformer.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 02, 2018, 10:36:32 pm
content: I'm impressed - given ZERO documentation, this is some progress.I was really willing to detour to Neulussheim. Of course, this would not guarantee any result either.

author: capt bullshot
author_rank: Super Contributor
timestamp: December 03, 2018, 06:35:02 am
content: Quote from: Neomys Sapiens on December 02, 2018, 10:36:32 pmThanks, this thing wasn't too hard.QuoteIf that company was run like the small one I've worked for in the 90's, there wouldn't exist any useful documentation that could be given to a customer. Anyway, having some kind of schematic still would be interesting, so maybe I could figure out what these 4 control switches that aren't doing anything obvious were intended for. I could reverse the schematics from the boards, at least the interesting ones, but I believe it's too much effort now that it's working and usable as intended.

author: Berni
author_rank: Super Contributor
timestamp: December 03, 2018, 07:47:11 am
content: Nice progressThis is why i like old designs where things are done with just basic chips like opamps and logic. You can always reverse engineer your way trough it given you put enough time into it.Once there is a microcontroller in there you have no idea what is happening inside. Even if you did want to read out the code and disassemble it you most likely can't cause they are always locked from reading.