Always fun to see old military gear. I was a Marine avionics tech in the late 1960's. We had 3-phase 400 Hz inverters in our vans but they were not used as we had 400 Hz generators supplying power. I assume they used similar low frequency switching as back in those prehistoric days semiconductors had severe switching speed limitations.
Glad you enjoyed the video. Often those old power switching transistors were germanium instead of silicon. I have a Unitron 3ph 400Hz inverter in the shop, I repaired it many years ago, most of the power transistors were fried and it was very difficult to find the replacements.
The transformer portion of that inverter is a ferroresonant power supply. Same a Sola, except the primary is driven from the inverter instead of a 120 volt winging. The immediate giveaway was the 600 volt output, which will go to the large oil filled cap forward of the transformer. The core is run in saturation all of the time as a means of voltage regulation, regardless of load or input voltage (within reason). That's where most of the 125 watts is lost. The 600 volt winding and the oil filled cap are a tank circuit, resonant at 60 cycles. The output voltage should rise when the frequency is raised up to spec. What a super cool piece. Would be neat to see a scope on the output.
Thank you for the information. You might like to see the follow up video ruclips.net/video/Q2KF4k_8daE/видео.html I do measure the output on a scope and adjust the frequency which as you mention raised the voltage. In the follow up video I ask if anyone has ideas about the 600 volt circuit. Your info is exactly right.
Your videos are very helpful. I'm 61 and have mobility issues, and have been building a lab and gathering gear for a few years now. Almost ready to launch a channel and get down to it. So I really appreciate your videos. They really help a lot of folks. Me included. You keep on doing it and I'll keep watching it. Peace.
@@fullwaverecked I'm glad you find the videos helpful. I'll definitely continue to share more projects and electronic topics. Have fun with your lab, projects, and videos!
The reason for the 20A NEMA 5-20 receptacle is so extension cords with NEMA 5-20 plugs will fit. Another important reason for the potential marking on the fuseholder cap is cuz those fuseholders were also made for 24V to 32V applications with an incandescent lamp in the cap. Such caps are usually orange or yellow. Made in the mid 1980s as there is a 1983 date code on one of the TO-3 transistors on one of the control boards.
I noticed numerous 83 date codes on IC's and capacitors. Fits with the contract date. Yes I have seen the fuse holders with incandescent bulbs colored as you mention.
Looking at corporate filings, it seems Fermitek went out of business in 1993 - first filed as a corporation in 1976. Its President is listed as William C. Burwell and its listed address is now used by an HVAC company.
Interesting unit. Whenever I see "...tek" and "oregon" in the same title I instantly think of Tektronix, the well known test equipment manufacturer. Possibly they had some connection. A search of historical Oregon business records show that Fermitek was registered in 1976 in Tualatin, OR and dissolved in 1993. I found a few references to them in government contracting/bidding documents. Their business address was just a small, light industrial site in the south suburbs of Portland. Probably the name was just inspired by Tektronix.
Ouch. Bad one even though it is "green" 😀. Thanks for showing. I have no military equipment and will not have for all the obvious reasons. At least you can charge your iphone now.😁
You can find them on eBay. The lamp does not care about the frequency. Only the voltage is important. Yes it is made for 115-120 volts, you can use a lower voltage but the current draw is less therefore the power is less. Above 120 volts will shorten the lamp life or even burn it out immediately.
low efficiency might be caused bij the fact that the transformer is driven bij an audio style amplefier to its max voltage output, maybe somewhat clipped at the peak, what makes the noise sound sharper through the extra hormonics produced at tge clipping point.
I wouldn't really compare it to an audio amp style output stage as this uses two SCR's to drive the primary winding. Yes it saturates the transformer and clips the waveform by design.
So, it takes 1200 watts on the DC side to make 500 watts AC. Wow, the old UPS's and stuff I worked on were never that inefficient. And that thing must get pretty HOT too.
Nope, something went wrong in your math. At 300 watts it's drawing 412.8 on the DC side a net conversion loss of 112.8 watts. 72.7% efficiency assuming the bulb is actually drawing 300 watts.
Yes it is power hungry! The ferroresonant transformer runs in saturation and gets quite hot by design. Being that it was built for the military I think rugged and indestructible were the goals over being efficient.
I wonder how the sinewave looks like on the output. Is it a true sinewave inverter or a modified inverter or something in the middle? judging from the sound it might be a modified inverter but that's just a guess
Some of these units used a ferroresonant Xfmr on the output to clean up the sine wave and assist with voltage regulation. That adds lots of weight. Everything needed tons of filtering back then.
In most scenarios inverter power rating is primarily like this: 3000w inverter, in actuality that would be peak, under continuous load it's half that so 1500w. You have to look out for peak power and continuous power. Continuous power is what it can supply continuously.
It depends on how it is rated and often peak values are listed for advertising purposes but the actual continuous rating is lower. In this case the 500 watt is a continuous rating.
Yes, the transformer is driven in a very similar manner in one of those but since they aren't ferroresonant the output is non-sinusoidal. The output of these things is actually a very clean sine wave.
Nearly all military inverters are of the ferroresonant low-frequency type. They do this so that the output has a very precise voltage which changes very little under varying loads. Even though this is a square-wave inverter its output is actually much cleaner than a modified sine wave unit using high frequency transformers-it is actually very close to a pure sine wave. For the equipment these are designed to run this is extremely important. These ferroresonant inverters also use far fewer components than a high frequency inverter, meaning they will have much higher long-term reliability.
@@lexpee Yes, and modified sine-wave inverters of even 10-15 years ago are extremely efficient. But when you are running very sensitive electronics and the inverter just has to work this is the best way to do it. And very large inverters are almost always the ferroresonant type.
Always fun to see old military gear. I was a Marine avionics tech in the late 1960's. We had 3-phase 400 Hz inverters in our vans but they were not used as we had 400 Hz generators supplying power. I assume they used similar low frequency switching as back in those prehistoric days semiconductors had severe switching speed limitations.
Glad you enjoyed the video. Often those old power switching transistors were germanium instead of silicon. I have a Unitron 3ph 400Hz inverter in the shop, I repaired it many years ago, most of the power transistors were fried and it was very difficult to find the replacements.
The transformer portion of that inverter is a ferroresonant power supply. Same a Sola, except the primary is driven from the inverter instead of a 120 volt winging. The immediate giveaway was the 600 volt output, which will go to the large oil filled cap forward of the transformer. The core is run in saturation all of the time as a means of voltage regulation, regardless of load or input voltage (within reason). That's where most of the 125 watts is lost. The 600 volt winding and the oil filled cap are a tank circuit, resonant at 60 cycles. The output voltage should rise when the frequency is raised up to spec. What a super cool piece. Would be neat to see a scope on the output.
Thank you for the information. You might like to see the follow up video ruclips.net/video/Q2KF4k_8daE/видео.html I do measure the output on a scope and adjust the frequency which as you mention raised the voltage. In the follow up video I ask if anyone has ideas about the 600 volt circuit. Your info is exactly right.
G.I. Inverter! All the lovely military electronics... Beauty.
15:18 Mr Carlson's Lab inspired warning? Nice.
Holly molly, no wonder it's so heavy. Thanks for posting. USMC '81 - '91.
Ya a lot of iron in there! Thank you for your service.
@@EriksElectronicsWorkbench And thank you for yours as well. Nice bit of kit. Cheers!
Your videos are very helpful. I'm 61 and have mobility issues, and have been building a lab and gathering gear for a few years now. Almost ready to launch a channel and get down to it. So I really appreciate your videos. They really help a lot of folks. Me included. You keep on doing it and I'll keep watching it. Peace.
@@fullwaverecked I'm glad you find the videos helpful. I'll definitely continue to share more projects and electronic topics. Have fun with your lab, projects, and videos!
@@EriksElectronicsWorkbench Cool! Will do!
The reason for the 20A NEMA 5-20 receptacle is so extension cords with NEMA 5-20 plugs will fit.
Another important reason for the potential marking on the fuseholder cap is cuz those fuseholders were also made for 24V to 32V applications with an incandescent lamp in the cap. Such caps are usually orange or yellow.
Made in the mid 1980s as there is a 1983 date code on one of the TO-3 transistors on one of the control boards.
I noticed numerous 83 date codes on IC's and capacitors. Fits with the contract date. Yes I have seen the fuse holders with incandescent bulbs colored as you mention.
Bravo.......love thet hummer.......emf........Hz frenquecy.......try a radio near it......cheers
Looking at corporate filings, it seems Fermitek went out of business in 1993 - first filed as a corporation in 1976. Its President is listed as William C. Burwell and its listed address is now used by an HVAC company.
Странно но APC в те годы уже выпускала инверторы и ИБП более компактные и эффективные и с идеальной синусоидой Видимо их схемы были в секрете
those old SCR inverters were tough. MOSFETs are tough if correctly designed, but even the more expensive ones seem to be toys 😒
Yes agree! Many modern inverters just don't hold up.
Interesting unit. Whenever I see "...tek" and "oregon" in the same title I instantly think of Tektronix, the well known test equipment manufacturer. Possibly they had some connection. A search of historical Oregon business records show that Fermitek was registered in 1976 in Tualatin, OR and dissolved in 1993. I found a few references to them in government contracting/bidding documents. Their business address was just a small, light industrial site in the south suburbs of Portland. Probably the name was just inspired by Tektronix.
Inefficient, but built like a tank. Could probably drop it off a truck with no harm done.
Ouch. Bad one even though it is "green" 😀. Thanks for showing.
I have no military equipment and will not have for all the obvious reasons.
At least you can charge your iphone now.😁
19:50 Где можно приобрести такую лампу? Она рассчитана на напряжение частотой 60 Гц и вольтажом 115 В?
You can find them on eBay. The lamp does not care about the frequency. Only the voltage is important. Yes it is made for 115-120 volts, you can use a lower voltage but the current draw is less therefore the power is less. Above 120 volts will shorten the lamp life or even burn it out immediately.
Did you look under the lid.? There maybe a schematic label .. Try straightening out the input wires..
No schematic inside the lid. I wish there was.
low efficiency might be caused bij the fact that the transformer is driven bij an audio style amplefier to its max voltage output, maybe somewhat clipped at the peak, what makes the noise sound sharper through the extra hormonics produced at tge clipping point.
I wouldn't really compare it to an audio amp style output stage as this uses two SCR's to drive the primary winding. Yes it saturates the transformer and clips the waveform by design.
It uses 5A, which is 125W just to hum. That's a lot these days.
Yes the idling current is high compared to modern inverters.
So, it takes 1200 watts on the DC side to make 500 watts AC. Wow, the old UPS's and stuff I worked on were never that inefficient. And that thing must get pretty HOT too.
Nope, something went wrong in your math. At 300 watts it's drawing 412.8 on the DC side a net conversion loss of 112.8 watts. 72.7% efficiency assuming the bulb is actually drawing 300 watts.
Yes it is power hungry! The ferroresonant transformer runs in saturation and gets quite hot by design. Being that it was built for the military I think rugged and indestructible were the goals over being efficient.
I'm almost positive that you can get the manual for this unit. Just lookup the P/N and see what happens.
There is only a national stock number on the unit and looking that up online does not have any matches.
I wonder how the sinewave looks like on the output. Is it a true sinewave inverter or a modified inverter or something in the middle? judging from the sound it might be a modified inverter but that's just a guess
Check out the follow up video ruclips.net/video/Q2KF4k_8daE/видео.html I measured the output on an oscilloscope.
Some of these units used a ferroresonant Xfmr on the output to clean up the sine wave and assist with voltage regulation. That adds lots of weight. Everything needed tons of filtering back then.
When I saw it was labeled as "Old Style" I expected a mechanical vibrator. :)
Not quite that old lol
If an inverter is rated at 500w can we go up to 500w. I always thought you need to go upto only 0.6 of a rated inverter.
In most scenarios inverter power rating is primarily like this:
3000w inverter, in actuality that would be peak, under continuous load it's half that so 1500w. You have to look out for peak power and continuous power. Continuous power is what it can supply continuously.
It depends on how it is rated and often peak values are listed for advertising purposes but the actual continuous rating is lower. In this case the 500 watt is a continuous rating.
Sounds like an apc back u.Ps
Yes, the transformer is driven in a very similar manner in one of those but since they aren't ferroresonant the output is non-sinusoidal. The output of these things is actually a very clean sine wave.
Bloody noisey 😂😊
At that time there were better inverters such as Victron Atlas inverters with a higher efficiency
This was built for the military and they have their own way of doing things. Yes other types of inverters existed at the time this was built.
Nearly all military inverters are of the ferroresonant low-frequency type. They do this so that the output has a very precise voltage which changes very little under varying loads. Even though this is a square-wave inverter its output is actually much cleaner than a modified sine wave unit using high frequency transformers-it is actually very close to a pure sine wave. For the equipment these are designed to run this is extremely important. These ferroresonant inverters also use far fewer components than a high frequency inverter, meaning they will have much higher long-term reliability.
The latest generation of inverters have an even higher efficiency and lower self-consumption.
@@lexpee Yes, and modified sine-wave inverters of even 10-15 years ago are extremely efficient. But when you are running very sensitive electronics and the inverter just has to work this is the best way to do it. And very large inverters are almost always the ferroresonant type.
You use camping
I haven't although it certainly would do fine outdoors but it is not very efficient so batteries would not last long. Carrying it would be a workout!