Omni
Yes, I did "my time" at Northeastern University some 30 years ago (loved that co-op thing... paid for school).
I hate to disappoint you, but the
While I'm not familiar with the Astro-Med Dash10... after a google search, that does not appear to be a very good instrument to do power supply testing (I understand having to use what you got, but...). A sample rate of 250K/sec and a bandwidth of 25kHz just won't get you there. It might be acceptable for some basic tests on a linear, but forget ANY off-line switchers or DC-DC's. I don't see any gain/phase modules under conditioners and accessories. Using that instrument, how exactly were you able to generate Bode Plots to determine stability? Did you generate them over temperature? With and without capacitive loading? Where was your "injection point"?
Transient testing with a active load unfortunately SUCKS, but everyone sorta does it. I have yet to see an active load, whether running in current mode or resistive mode, that didn't have overshoot... you see the problem with that, right?
So one more time, would you care to share your test result's?
Yes, I did "my time" at Northeastern University some 30 years ago (loved that co-op thing... paid for school).
I hate to disappoint you, but the
IS NOT an industry standard for testing power supplies, it is Agilent's!! While its possible that some schools/courses may have chosen "their" test methodology to use in the classroom, it should NOT be presented as something thats
it IS NOT! Yes, there is a certain core parameter set that everyone tests, but by no means is it patterned after something Agilent does.
While I'm not familiar with the Astro-Med Dash10... after a google search, that does not appear to be a very good instrument to do power supply testing (I understand having to use what you got, but...). A sample rate of 250K/sec and a bandwidth of 25kHz just won't get you there. It might be acceptable for some basic tests on a linear, but forget ANY off-line switchers or DC-DC's. I don't see any gain/phase modules under conditioners and accessories. Using that instrument, how exactly were you able to generate Bode Plots to determine stability? Did you generate them over temperature? With and without capacitive loading? Where was your "injection point"?
Transient testing with a active load unfortunately SUCKS, but everyone sorta does it. I have yet to see an active load, whether running in current mode or resistive mode, that didn't have overshoot... you see the problem with that, right?
So one more time, would you care to share your test result's?
audioguru2
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You don't need to blow it up by seeing that it doesn't make 3V at 3A without overheating.
You don't need to see that it doesn't make 30V at 3A.
You don't need to see a very high amount of ripple on its output at any output higher than 25V and at 3A.
Just pretend that it works very well.
You don't need to see that it doesn't make 30V at 3A.
You don't need to see a very high amount of ripple on its output at any output higher than 25V and at 3A.
Just pretend that it works very well.
Wow...let's just gang up on the guy. :
I think if he is happy with the power supply that he built, he doesn't owe anyone test results. Just a note to the community that he is satisfied with the project.
Admin of this site also built the original and it did not cause such problems as burning up.
I see 90 some pages of discussions based on theory suggestions. Where are the test results for all of these? Why does someone have to provide test results because he does not agree with another 's theory? Let's request the theory guy provide the test results on both designs since he has implemented the discussion of change.
(In other words) You have made your opinion. Let it go.
MP
I think if he is happy with the power supply that he built, he doesn't owe anyone test results. Just a note to the community that he is satisfied with the project.
Admin of this site also built the original and it did not cause such problems as burning up.
I see 90 some pages of discussions based on theory suggestions. Where are the test results for all of these? Why does someone have to provide test results because he does not agree with another 's theory? Let's request the theory guy provide the test results on both designs since he has implemented the discussion of change.
(In other words) You have made your opinion. Let it go.
MP
The Astro-Med dash10 is a high end multi channel chart recorder used to chart a multitude of variables in graph form.
The results while testing will show conclusive if an outside problem has occured.
Additionally, how you can criticize Agilent is totally beyond my understanding, the latter manufacturer has some of the most intelligent/professional engineering based throughout the World.
I have been employed as a Govt electrical engineer for a long time, during the latter time we cater to Agilent for their superb support.
The Agilent method of testing a power supply is essentially the same concept used by a variety of high end resource facilities.
I agree with MP, the aspect of going into a deep discussion would be pointless...
However, i will provide a hint concerning how to perform temperature stability.
Hopefully, it will provide some useful insight.
Example:
Thermal plate, NI multipoint thermometer using specific locations on the plate (multiple thermocouplers), 2 - Neslab chillers (hot - cold), hot supply tank, cold supply tank along with programming in visual basic or C+ in reference to transistion/cycle time connected via the RS-232 port.
indulis,
This subject is becoming rather tiring, i would think with a so-called University degree you would have an idea as to how the above is performed?
Take the time and keep yourself up to date regarding new concepts, the latter will prove to be very helpful.
audioguru,
You appear to enjoy continuing a losing argument, your method of testing is very subjective.
After reading other threads/posts it is obvious you cannot accept a failure, the latter is the only way you will step beyond your superficial ego; learning is a virtue!
MP,
"(In other words) You have made your opinion. Let it go." DITTO!
The results while testing will show conclusive if an outside problem has occured.
Additionally, how you can criticize Agilent is totally beyond my understanding, the latter manufacturer has some of the most intelligent/professional engineering based throughout the World.
I have been employed as a Govt electrical engineer for a long time, during the latter time we cater to Agilent for their superb support.
The Agilent method of testing a power supply is essentially the same concept used by a variety of high end resource facilities.
I agree with MP, the aspect of going into a deep discussion would be pointless...
However, i will provide a hint concerning how to perform temperature stability.
Hopefully, it will provide some useful insight.
Example:
Thermal plate, NI multipoint thermometer using specific locations on the plate (multiple thermocouplers), 2 - Neslab chillers (hot - cold), hot supply tank, cold supply tank along with programming in visual basic or C+ in reference to transistion/cycle time connected via the RS-232 port.
indulis,
This subject is becoming rather tiring, i would think with a so-called University degree you would have an idea as to how the above is performed?
Take the time and keep yourself up to date regarding new concepts, the latter will prove to be very helpful.
audioguru,
You appear to enjoy continuing a losing argument, your method of testing is very subjective.
After reading other threads/posts it is obvious you cannot accept a failure, the latter is the only way you will step beyond your superficial ego; learning is a virtue!
MP,
"(In other words) You have made your opinion. Let it go." DITTO!
audioguru2
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The owner of this site, Mixos, reported, "... that's what we are trying to do with this power supply right now, to make it reliably live up to its specs !!"
Mixos reported that, "Trying to get more then about 25 V at 2.1 Amps show increasing ripple in the output, and trying to get higher voltages than that was not possible."
As Mixos reported to Staigen in a personal message, his project broke down and needed repairs.
Staigen wrote, "The reason for the delay is that the PSU Mixos have and do some testing on, brooke down. He has now repaired it, and hopefully he can do further tests this week."
Others have also reported that the project cannot make 30V at 3A and parts get extremely hot. Theory proves it and shows why.
Mixos reported that, "Trying to get more then about 25 V at 2.1 Amps show increasing ripple in the output, and trying to get higher voltages than that was not possible."
As Mixos reported to Staigen in a personal message, his project broke down and needed repairs.
Staigen wrote, "The reason for the delay is that the PSU Mixos have and do some testing on, brooke down. He has now repaired it, and hopefully he can do further tests this week."
Others have also reported that the project cannot make 30V at 3A and parts get extremely hot. Theory proves it and shows why.
audioguru2
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Hi Dr. Steve,
I thought you make only medical electronic projects. ;D
Are you going to make the faulty original project that doesn't make 30V at 3A and gets hot enough to fail, or are you going to make the improved one?
I thought you make only medical electronic projects. ;D
Are you going to make the faulty original project that doesn't make 30V at 3A and gets hot enough to fail, or are you going to make the improved one?
audioguru2
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The original expensive transformer doesn't have enough voltage and current for the improved version. It would be a waste to throw it away. I don't know how long it will last when it will be overloaded sometimes.
I don't know how long the frying time will be before the overheated transistors, rectifier diodes and resistors fail. Maybe you can add a high velocity fan.
The ICs have a supply voltage that is higher than their max allowed voltage. I don't know how long they will last.
I don't know how long the frying time will be before the overheated transistors, rectifier diodes and resistors fail. Maybe you can add a high velocity fan.
The ICs have a supply voltage that is higher than their max allowed voltage. I don't know how long they will last.
audioguru2
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The schematic is the same except there are two output transistors to share the heat. The output transistors have emitter resistors to equalize their gain.
The improved parts list has an upgraded transformer, upgraded rectifier, upgraded main filter capacitor, high voltage ICs, transistors that are rated for more heat and resistors with a higher power rating. The main zener voltage reference diode is selected with a part number and its supply resistor has its value selected for best performance.
Here is the improved parts list:
View attachment 40461
The improved parts list has an upgraded transformer, upgraded rectifier, upgraded main filter capacitor, high voltage ICs, transistors that are rated for more heat and resistors with a higher power rating. The main zener voltage reference diode is selected with a part number and its supply resistor has its value selected for best performance.
Here is the improved parts list:
View attachment 40461
audioguru2
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I order parts from Digikey or Newark. If I order before 8:00PM then they deliver it to me the next morning.
Omni
Yes tiring if you don't have the answer. Let me reiterate... maybe you didn't read the previous posts carefully enough and missed it before, for the last 15 years of my working career I've been employed as a power supply design engineer, guess what I do... design power supplies!! I am VERY familiar with those tests and many more. I know exactly how to perform them and what the proper equipment is to do it!! I NEVER said I didn't know how to do the test. It is presumptuous of you to assume that just because someone asks a question, that they don
audioguru2
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There are more than 29,000 members here and I am the only one who fixes these lousy projects that don't work properly.indulis said:
Hi there,
I've been reading through the posts, and have decided to build this power supply into my bench supply which I'm upgrading - the negative pumping scheme is more clever than my own design with a separate dual supply for the op amps!
However, would just like to ask a question about the R47, 10W emitter resistors for the output pass transistors. I have a couple of R22, 5W resistors handy, and believe it would be fine to use them. Since the 2N3055 transistors are parallelised, the max current through each is 1.5A. We want a 0.2V drop across he resistors, so R will be 0.2/1.5=0.13. So R22 is about right. And power wise,
P=(1.5)^2x0.22=0.495W.
Am I missing something?
Many thanks,
I've been reading through the posts, and have decided to build this power supply into my bench supply which I'm upgrading - the negative pumping scheme is more clever than my own design with a separate dual supply for the op amps!
However, would just like to ask a question about the R47, 10W emitter resistors for the output pass transistors. I have a couple of R22, 5W resistors handy, and believe it would be fine to use them. Since the 2N3055 transistors are parallelised, the max current through each is 1.5A. We want a 0.2V drop across he resistors, so R will be 0.2/1.5=0.13. So R22 is about right. And power wise,
P=(1.5)^2x0.22=0.495W.
Am I missing something?
Many thanks,
Last edited by a moderator:
audioguru2
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Hi Chapz,
Welcome to our forum. ;D
The 0.33 ohm emitter resistors are used to equalize the gains of the output transistors because the 2N3055 transistor has a wide range of current gain. Members who tried 0.22 ohm emitter resistors reported that one transistor became much hotter than the other because their gains were different and 0.22 ohms wasn't enough to make them nearly the same. Try it with your transistors or test many transistors.
1.5A squared x 0.33 ohms= 0.74W. Use 2W resistors so they don't scorch the pcb.
Welcome to our forum. ;D
The 0.33 ohm emitter resistors are used to equalize the gains of the output transistors because the 2N3055 transistor has a wide range of current gain. Members who tried 0.22 ohm emitter resistors reported that one transistor became much hotter than the other because their gains were different and 0.22 ohms wasn't enough to make them nearly the same. Try it with your transistors or test many transistors.
1.5A squared x 0.33 ohms= 0.74W. Use 2W resistors so they don't scorch the pcb.
Hi audioguru,
Thanks so much for your reply and advice! I will try it with 0.33 ohm as well as 0.22 and 0.47 ohm resistors and let you know what I find.
One other thing; wouldn't it make more sense to use a power FET (n-channel) for the output pass transistors? That way we wouldn't need to use emitter resistors since the drain current actually decreases with increasing temperature. So something like two parallelised IRF640's?
Your opinion would be much appreciated.
Thanks so much for your reply and advice! I will try it with 0.33 ohm as well as 0.22 and 0.47 ohm resistors and let you know what I find.
One other thing; wouldn't it make more sense to use a power FET (n-channel) for the output pass transistors? That way we wouldn't need to use emitter resistors since the drain current actually decreases with increasing temperature. So something like two parallelised IRF640's?
Your opinion would be much appreciated.
